Big Bore Small Block! GM's missed opportunity

[@TheRocco28]

Way back in the day, the engine in my 1978 Zed28 died. I was too broke to fix it, but my buddy had an Oldsmobile 403 lying around. We installed that and put 3.08 gears in the back. That thing used to hunt 5.0 Mustangs on Hwy 401. Anyone with an Oldsmobile 307 in their Cutlass or Cadillac would be wise to upgrade to a 403. Everything bolts right up. Happy New Years 🎉 Pat, keep up the great videos!!!

[@DennisL-n6i]

Yesh, that is what I am talking about! Awesome 😎. Even in a 77 Cutlass that 403 of mine got with it.

[@thereluctantgearhead4544]

If your trying to build a 750hp NA racing engine, this aint the block for you. But speaking from experience, they will take 450-500hp without coming apart. Keep the revs down and they hold up just fine. I kept mine under 6500rpm. Ran in the 11s NA. 7.50s in the 8th. Drove it everyday. That was 35yrs ago. Even with a girdle they are still limited. But not everybody needs a 1000hp engine despite all the bullshit on the Internet. Most people dont even need 300hp.

[@roberthollinshead2325]

We built one up for my buddies 79 Trans Am. We zero decked it, bored .030, balanced it. Put 1969 350 rocket heads ported with bigger intake valves. Performer intake, 750 holley, headers, 238@.050 cam. It ran really good 👍🏻

[@thereluctantgearhead4544]

Best Olds block to build a monster with is the 350 DX block. Damn near bulletproof.

[@jarrodjones9275]

As you said, damn near indestructible. Solid mains, already set up for a roller cam, and easy to build a bigger inch combo with a cut down counter weight 425 crankshaft. Not to mention that they aren’t too difficult to locate, as usually everyone runs from the 350 diesels, not realizing that they make a great foundation for a gas engine. Just refrain from picking up a 350D, as they had smaller head bolts and were set up for a flat tappet camshaft.

[@thereluctantgearhead4544]

Those 403s are stronger than they appear. I gave one hell for a while at around 460hp level. Block still fine. Sprayed it with a 150 shot for about 2 miles on a back road, broke a ringland in the piston from not enough gap. Thats all that happened. Try to find a forged 330 crank. 403 rods are strongest SBO rods made. KB pistons get the compression up. I used 455 heads on mine. Pretty good engine, but they have a limit. Id keep it under 500hp NA. That windowed main block is scary, but not as weak as one would think. Dont turn it 8000rpm either. Itll spit the rotating assembly out on the road. I fid take mine to 6500rpm many times, but usually shifted around 6000-6200rpm. 455 heads are a easy swap, just need a intake with enough meat to port match to the bigblock runner height. Theres a few that will work. Best modern intake for the swap would be the Edelbrock Super Victor for SBO.

[@ryangulley2051]

Bahahaha

[@toefield251]

Definitely a missed opportunity. In 1982 I was in my dad's 1977 Buick Electra with a 403 and I raced my buddy who was driving his dad's brand new 1982 z28 with the 305 cross fire injection motor. I was behind him and I passed him and walked away from him pretty easily. I know that the 305 cross fire injection motors are pretty weak but that camaro was so much lighter and aerodynamic but damn that 403 pulled.

[@Thundarr995]

I remember back when I was a kid. It was 1988, and my dad was taking us to see Killer Klowns from Outer Space. We were in a 76 Nova. We raced a gen 3 Camaro stop light to stop light, and we won by half a car length. That guy wouldn't even look at us. Rofl.

[@terrypikaart4394]

I had same car, original 403 had a rod out the pan. Pulled another 403 from a smashed LeSaber and dropped it in Electra. Wow i liked that car for so many reasons, never should have sold it!..

[@kentbuerk9479]

I don't understand why you don't have more subscribers. It truelly baffles me.

[@thereluctantgearhead4544]

Because the masters of the universe want you driving a cell phone with wheels and GPS so they always know where you are...... They suppress channels that promote old school engines unless you work for Motor trend. They actually remove views from my videos daily. Shits real strange. Totally rigged platform.

[@thereluctantgearhead4544]

I just explained it and utube removed my comment. Funny how that works. It's got Alot to do with what the self appointed masters want.....

[@thereluctantgearhead4544]

They remove views & likes from my videos daily.

[@thereluctantgearhead4544]

I made a video proving it and they removed it.

[@thereluctantgearhead4544]

Shits rigged.

[@mb-fs1yo]

Had one of these in a 77 98 regency, ran great, lots of power, great fuel economy ( 22 on the highway, no overdrive, no fuel injection). Always wanted Mondello to do a non windowed cast or aluminum version of it.

[@jeffjarquin5600]

403 olds are great! I've built several sleepers with them. I like to use the 1968-71 350 rocket heads casting #'s 5 through 7. Add the 455 2.07 intake and 1.68 exhaust valves. Lots of bowl and short side radius work. Zero deck the block, due to the fact oem head gaskets were steel shim type. Which your not gonna find anymore. With the stock type pistons and the small chambers on the early small block heads and decking of the block near 9.85:1 is easy. A cam with 224/234 on a 112 lsa is plenty due to the fact that more than 6000rpm will work on the mains. Use the mondello oil restrictors. A holley 4779 on a old holley street dominator intake will make good power for it's height. Port the intake roof all that it will allow with reason. Then port the heads to match. There is enough material in the early heads to raise the port roof to bb olds size. I prefer the rpm intake, but you stated you were using a shaker. When I started building olds engines the only aluminum heads were batten out of Romulus Michigan. Shoot Dick Miller was in Michigan at the time too. I'm excited to see this build as it has been 17 years since my last 403 build.

[@DennisL-n6i]

What sucks is I can get sbc to fit a 2.10" intake valve. Why then cannot an olds with a 4.375" bore fit the valve size it actually needs? Someone needs to design heads for these things that ignore factory design because it doesn't cut it.😊

[@tking7513]

@@DennisL-n6i Edelbrock's new big block heads have 2.15" intake valves and they'll work great on a 403 if using flattop pistons , and with a ported RPM intake.

[@leonmanning2429]

Following your build. In the process of building one now for 80 trans am. We are using a N crank from 69 350, a main cap girdle, 6 inch Chevy rods, lates version edelbrock big block heads(small block’s weren’t available) custom diamond pistons and hydraulic roller cam( specs to be determined yet). Also installing a 200 4R transmission and 3.42 gear. Car is just a driver.

[@aidenstefanson2175]

My dad has a 79 Trans-am with the 403. I remember reading about Joe Mondello trying to sleeve the Olds diesel block to build a high revving 403, but I'm not sure there was ever a running engine. Those huge cc chambers on the smog era heads killed all the power potential. I was jazzed to hear about the new edelbrock aluminium heads for Oldsmobile engines. I've seen a 403 swapped into a Hurst-Olds that was pretty awesome. Underappreciated engine.

[@thereluctantgearhead4544]

They make flattop pistons for them and milling the heads & decking the block will get the compression up. Mines over 10.75-1 with milled bigblock heads. KB 5cc .024 over flattop pistons. .038 head gaskets.

[@thereluctantgearhead4544]

Best thing to do with the DX block is drop a forged 425 crank in it with the rod journals turned down to 2 inch early SBC size & offset for a 4 inch stroke. Use 6 in SBC H-beams for a 2 inch rod journal. Gotta be slightly narrowed to fit. Block thick as hell, can build a 440ci SBO pretty easy with one. Make a shitload of power and be durable as hell. I've seen them well over 1000+HP. Dave Smith ran NHRA Pro Stock with them in the early 80s. He's was making around 1000hp NA with them at 400 cube range. 900+HP at 340 cube range. They were radical as hell, cams over .900 lift, 15-1+ compression, sheet metal tunnelrams & twin Dominator carbs, heads that were a work of art. Headers with 2.5 in primary, 5 in collectors. Turning 9000+RPMs. Ran 7s in 1/4 over 40yrs ago. Dave Smith was the real Dr Oldsmobile. Believe him and Warren Johnson were pretty tight.

[@DennisL-n6i]

​@@thereluctantgearhead4544wow that must of been an aftermarket.olds style block. Ssrc or something. Well I am going to weld my block up with plates that close the windows, or what would be nice is a new nano molecular iron block casting.😊

[@whaddayawant2197]

Idk about the deisel sleeved blocks.. but I've heard the deisels to be good candidates for stroked Olds. Prob well over the 403 ci.

[@stevenbelue5496]

Mondello has a build series with the DX block here on youtube.

[@marcoceccarelli6415]

Great video I never knew that before. It kinda reminds me of a 400 d stroke with a 350 crank. Big bore short stroke motors Run excellent.

[@DanielStahler-m8f]

I have a stout 377 in my 3rd gen Camaro . Love how the big bore , short stroke run

[@captainrawn]

Pat, here's what I did to the 403 in my 79 TA that looks just like the one in your picture. Still own the car and drive it often in the summer. Has working AC and Cruise in it. If your customer wants a nice driver you might find this useful. When the car had 92,000 km on it I removed the engine and trans during the restoration. The engine ran well with good oil pressure and had only a small trace of blow by when hot. I took it down to the short block and inspected the bearings and so on. To my delight it was all still in very good condition so I made the decision to re-use the block and rotating assembly as is so it is all stock GM original. My goal was to double the HP and get the torque into the low 400's in a budget friendly manner and I believe I have accomplished that and more. I had a new set of Speedmaster Olds heads at the time but opted not to use them as they wouldn't allow me to retain a mechanical fuel pump. I purchased a set of #5 350 small block heads and had 2.07 intake and 1.68 exhaust valves and 3/8" ARP screw in studs installed in them. Also drilled the holes out on a drill press from the original 7/16" size to fit the larger 1/2" 403 head bolts. They were shaved for flatness and I did cc them but forget what the result of that was. Prior to having that done I ported them on both intake and exhaust sides and they looked alright but I don't claim to be an expert at porting. I used a Cometic MLS .027 head gasket to help raise the compression. I calculated the compression to be around 9.7 to 1 and it cranks at 160 psi. For a cam I used an Elgin E-1074-P flat tappet 224/234 @ .050 with 496/520 in/ex lift, Comp lifters, custom length push rods, and slightly larger than stock 1.65 roller rockers. (In retrospect for this car I might use the E-977-P 214/224 @.050 473/497 cam or Rhodes lifters for improved overall drivability). The intake is a port matched Edelbrock Performer for stock shaker hood clearance reasons. I reworked the original Q jet with helpful advice from Cliff Ruggles book on those carbs. I modified the stock HEI timing curve to be 36 degrees all in at approx. 2900 RPM. Likes to idle with 19 to 20 degrees mechanical advance at 900 RPM and produces 11ish inches of vacuum at 3500 feet altitude. Limited the vacuum advance to 10 degrees so 46 total is the most it ever sees. This engine is currently set up with ported vacuum advance due to idle in gear tuning reasons. Has Ebay stainless $155.00 headers and a full 2 1/2" Pypes X pipe exhaust system on it. Stored the original turbo 350 in favor of a modified 2004R with a 2200 stall lockup convertor. It would be better with a 2600 stall. For rear gears I removed the 2.41's and installed 3.42's. The result of all this is a good running engine with zero valve train noise and a nice lopey idle. I'm confident that it makes around 375 to 400 HP and well over 400 ft lbs of torque. When I did this build 6 to 7 years ago I spent just over 2 grand on that engine. From a performance stand point it is a wee bit soft down low but not terrible, a looser convertor would fix that. It really starts to come on at about 3000 and pulls hard to as far as I have taken it which is 5800 RPM. It would keep pulling to 6 or more no problem at all but I am concerned with going that high. The first time I opened it up I was pleasantly surprised with the power it made. It cruises effortlessly down the highway at 120 KM and 2200 RPM and in doing so actually gets decent fuel economy. For comparison sake a friend of mine has a 79 TA with a very similar build on his 403. Used #6 small block heads with the valves from the 403 heads and a milder Comp high energy 268 cam. While it idles a little bit tamer with more vacuum, it performs better down low and if you nail it from a stop it does long burnouts at 5700 RPM in 1st gear with no issues. Has 3:42 gears and the original turbo 350. Would be a close race between his and mine but I would probably pull away up top. Another comparison is my Martinique blue 78 TA with a W72 Pontiac 400 4 speed. Just over 120,000 km original on it. Has the original bottom end, a ram air 3 cam, #13 ram air 3 heads, performer intake, an Edelbrock performer RPM Q jet, headers, and the stock 3:42 gears. It's well tuned and a nice car to drive but as they sit now in a drag race my 403 equipped TA would walk away from it. Hope some of that is helpful. Sorry for the novel lol. Cheers

[@cuttersperformance]

Thanks for all the info

[@BenL8257]

Always enjoy your content brother! Another winner

[@emillioesserman6879]

Also worked for a Buick dealership in 77 as a line mechanic pulled plenty of 403 for rear main oil leaks almost daily

[@cuttersperformance]

The ole rope seals 👎, did you ever try the ford rubber seals in them?

[@Imnotyourdoormat]

*Big Bore Short Stroker 377 Chevrolet's were ... **_badass._* *I'd like to have had 1 of those mothers in a 2900 lb Nova back in the day.* *383/400 MoPars are ultra "over square" engines too ...* *Watch the Don Garlits interviews Jr. Johnson video to see what a big bore short stroke motor can do for you.*

[@rotaxtwin]

Lots of good feedback on some legit 403 builds in the comments, that's great stuff. You got a good community going here Pat!

[@cuttersperformance]

Yeah it's a cool group of people here!

[@rotaxtwin]

Yeah, i agree, lots of potential. They were smog victims like everything from that era. Honestly, it was a small miracle that any performance came from GM at the time between the emission requirements & GM execs having their heads up their collective assets. Ive heard a few stories of guys mildly tweaking these and having some success. Just adding 10 degrees of timing and richening up the idle/transition is a start. But at the end of the day the bean counters kinda stole its could-be glory.

[@user-Dr.]

I have had interest in short stroke larger bore engines, I built a couple 302 Chevy's back in the 70's, early 80's, homemade ones, but I started road course racing years ago and I really needed to slow the engine rpm down for longevity of the valve trains, I've been building genII LT1's for some time now, settled on 3.75 stroke, (383's), keep em below 7,000, making over 600 lb/ft of torque on the engine dyno, I have my own special cam grind all for torque, 13.5-1 compression on 93 Sunoco, AFR heads that I work over myself, this engine has far more capability than was ever realized, it is by far the best version of the old small block, the reverse flow cooling is magic, keep the combustion area super cool, compression is almost unlimited, going higher on the next build.

[@Scott-su1wj]

You can make it good, it will great. Don't forget to set the rev limiter kinda low. . . Can't wait to see this one done. Keep up the good work as usual. !!

[@mikelovin7]

I know this is crazy but I'd like to see a 350 tbi build, not wild power but just good reliable power that would last a really long time in a k1500 everyday driver. I'm pretty sure there's room for improvement from OEM specs, like a roller cam that's a little better than stock but still work with the stock ECM, polish the head ports and intake ports, headers, ect. I already put a high flow cat with straight pipe and a TBI spacer and it made a huge difference in power and mileage, so I'm curious how much more difference other changes would make. As much as new trucks cost I'm hanging on to my old '94, besides I just love this 30 year old truck.

[@paulpollack9262]

From what I've read the Y-pipe from the exhaust manifolds is the biggest restriction. What kind of mileage improvement did you get? I wondered if you could use blow through turbo setup with the TBI.

[@mikelovin7]

@@paulpollack9262 True the Y pipe needs to change with the header change. I forgot to mention I set the timing up 6° from stock 0° too. I get 15-16 city and 18-19 hwy. I don't think a turbo would work well with the TBI, but I'm more of a N/A guy myself, I like the reliability and simplicity.

[@buzzwaldron6195]

'75 Olds 350" got direct port injection in '75 & up Cadillac Seville... TBI Chevy 350" prolly benefit from TBI throttle body off BBC 454 or 481 engines... Do you have Vortec truck heads? Best SBC heads Chevy ever used... good to 450+ HP...

[@mikelovin7]

@@buzzwaldron6195 I don't have the vortec heads, that's why I would like to see a reliable everyday driver TBI built here with it's best potential. I know I could go wild with it, but I'm just looking for improvements that would work with the stock ECM as if it could have came from the factory that way.

[@SaneCayne]

@@mikelovin7 You and me both, brother. I've got an '87 1/2ton SWB with the original 305 TBI. Runs fine, but have a 5.7 TBI core engine I'd like to build with a touch of hp enhancements and drop in.

[@msh6865]

This should be a cool build. My 79 SE Trans Am (Bandit Edition) had the 403 engine and was fantastic when it finally got rolling (2.73 gears). But, with only 185 hp in a very heavy car, it was a dog. How about the Olds 425? Where does it fall in the Olds engine family tree? A smaller version of the 455?

[@tking7513]

The 425's are considered one of the best Muscle Car engines to never be installed into a muscle car! 385 hp at 4,800 rpm/475 ft lbs @ 3,200 is the top rated version, ('66 Toronado). What's not to like with 10.5 compression, a 3.975" stroke steel crank, .921" diameter lifters, and 7.0" rods.

[@obbyjep7597]

I used some big block c heads a around 240@0.50 cam, it actually worked good for what it was. Never did blow up. The intake I used had enough metal to raise the ports to match the 455 heads. Defenetly a shame gm didn't make these blocks stronger. Seemed good enough for a street putter that didn't get revved much over 6000. Fairly light engine that made more power than a comparably modified 350sbc

[@WilliamDaniel-m6y]

Running 15 PSI on a crappy "windowed mains" 307 olds now for a few years. I truly remember them not being that open when we rebuild it. I broke the rings and pistons out tuning it the first time. Factory 40k engine with next to no ring gap.

[@MichaelCoger]

I had one in a Buick wagon and it ran great. Decent gas mileage and performance.

[@cuzz63]

Really hope the customer goes with the Aluminum heads. Cant wait to see.

[@BluMaGiKCj]

My first car was a 1978 olds cutlass with a 403. It actually had a hole in the block when motor was pulled.

[@Charles55mercado]

Still waiting on the 406 Vortech headed build video 🤞🏼

[@cuttersperformance]

It's next to go on the dyno

[@shaneshane1379]

I have built a couple 400 with vortec heads for dirt tracks cars. They won't flow enough. Sportsman darts make a big difference.

[@SaneCayne]

@@shaneshane1379 Iron Eagles work great on my street/strip 406. 11.7s in a very streetable 3940lb car.

[@off-roadmechanic]

Definitely a killer motor with some modifications

[@jsteed4388]

They are wonderful as long as you’re now planning on turning them over 5500 rpm on a regular basis. You can get by from time to time, but if you’re gonna make them rpm capable you’ll be ordering the Joe Mondello catalog…😂 I used the 69 455 blocks. Great motors. I had a 64,67,70 Olds Cutlass miss those cars. My brother still owns my 64

[@ctusser]

I liked this dude in that show Shameless, it’s cool he’s a motor-head too.

[@cuttersperformance]

What? 😆

[@patrickwendling6759]

had a TA 403 . it rocked

[@mattmusselman6499]

Always thought the same about 403. Dodge did the same with their 400. Big bore but at the wrong time. I believe it was based on the 383 "B" block.

[@basilcarroll9729]

There was talk of solid web 403s in full size station wagons . I scrapped a 1977 Buick estate wagon with a 403 , sorry to say they were open .

[@thisisyourcaptainspeaking2259]

I thought the 403 came with a steel crank? Thinking back, that must've been the 425. Anyway, may as well build a 455 for a street cruiser, IMO.

[@christopherpoucher483]

I had a 77 cutlass supreme with a 403 had pretty good power

[@evanm3209]

I didn't know that had such a large bore..it kind of sounds like the Mopar 400 architecture.: 4.32 bore, 3.375 stroke, though with a skirted block, they are strong

[@sbf_fox2434]

A channel called the Reluctant Gearhead detailed his 30 year old build of a 403 Olds. He used KB pistons, ported and decked J 455 heads and a Lunati Street Master camshaft in his build. He brought up most of the points you made. He was a fan of the engine and did not have problems with the bottom end. He brought up that 403 has 1/2" head bolts whereas the 455 has 7/16".

[@tracycurtright2671]

Only the 77s had solid webs. I built a 78 to replace the 5.7 diesel in my Cadillac and it made a great highway cruiser.

[@captainrawn]

Solid main web 403's do not exist. There's a 1 million dollar reward out there available to you if you can provide "solid" proof otherwise.

[@super1079]

Diesel blocks i think are solid block

[@oldsmobilecutlass1805]

I’m the one that helped design the new head from Edelbrock. It’s best to still use the 7111 intake with the new head, the same as if you were to use the big block head. However depending on which KB piston you plan to use, you may have to use the bb head, as the new small block head has a 68cc chamber might be too little if used with the 6cc KB piston. Newoldsperformance.com

[@RANDOMNATION907]

Big Bore and short stroke is perfect for high rpm applications. However, that windowed block won't handle much over 5,000 rpm. Please take my word on this. I've tried. Your customer is spot on in how he wants to use that engine. You should look into the last version of the Olds 350 diesel. The "DX" Block. It has larger 455 mains, is not windowed, has a higher nickel content and the last years it was produced utilized a roller cam and lifters like a Vortec 350. You can fairly easily convert them to high compression gasoline engines.

[@modeverything1]

We need Rocket Racing to make a small block version of their aftermarket Oldsmobile block!

[@UnconventionalMetal]

I have one out of a ‘79 TA sitting in my garage now just waiting for a project

[@zmanmd1641]

A girdle for the main caps would strengthen that windowed block enough to allow more power to be pulled from that engine. A set of ported heads with a custom intake and water crossover would complete the big power mods.

[@paulbass1369]

I have one of those engines built for a 1987 cutlass that I sold to my nephew, he put a 6.0 LS in it. Anyone interested in owning the 403 it's bored .030 with stock rotating assembly #7a heads with a crane cam 224/234 .487/.520 on 112 LSA also has Edelbrock performer rpm intake manifold. The heads are upgraded with the 403 valves, I don't have any use for the engine anymore as it's just a monument in my shop.

[@rogersome1413]

Can the webbs be filled?

[@Christopher-re2hl]

Yes that would have been a super engine if it weren't for the EPA

[@AcesNtheEND]

Well the aftermarket has taken over with blocks from Dart giving us 427 and 454 small blocks for what a couple decades now? At the time those Olds blocks were made there was no opportunity for them to be used for anything other than pushing around those 70's emissions land yachts.

[@inscoredbz]

I had a 403 olds that was stock out of a station wagon. It was a torque monster for such a short stroke. I would build one if the blocks didn't have those windows. Imagine cutting a 455 crank down to fit the 403 block.

[@scottosborne8735]

I hear the 403 blocks are thin with windowed main saddles.

[@buzzwaldron6195]

All seen exceptionally clearly in this video...

[@kruelzombieful]

First to comment!!! I love this channel! Thanks for the video. They are always informative!!!

[@Gearhead.327]

If you could stuff a 3.75" stroke crank in there it would yield @451 cu in with your 3.375 bore, @ 446 cu in with a stock bore(4.351) and 3.75" stroke. This was a huge missed opportunity for GM and Olds fans. Great video and top marks as usual.

[@cuttersperformance]

Yeah exactly! 451 cu inches with a large cam to crank distance to fit a large cam without interference and a tall deck to allow a decent rod 👌

[@buzzwaldron6195]

It defeats the advantages of a super short stroke...

[@tking7513]

There is an aftermarket 4.0" steel crank made for SBO. The easy build is a 350 sbo block bored .068 to 4.125" and a 4.0" crank for a 428ci engine and solid mains. You can find the limit of the gas blocks just using ported bbo heads.

[@gmkellz]

Had a 85 2 dr LeSabre with a 403 out of a 78 98Regency. I put a built turbo 400 dual 2 1/2 exhaust and a Holley 750 double pumper but a stock open rear. A buddy had a 85 5spd Mustang Gt and that Buick used to walk away from it. That 403 was the smoothest running engine I ever had. GM definitely missed out on

[@thundermountainatv]

Check into a olds 350 diesel block from back in the day I seem to remember it was big bore short stroke and had a spacing similar to the big Pontiac cranks … just another Frankenstein project from the 70s

[@yurimodin7333]

just like the sbc there is a reason the 383 stroker was a thing vs just running the 400. They pushed the limits too far just like the 400sbc......I had a 350 olds someone crammed into my 76 elcamino (i guess that was the only engine they had on hand).....that car was a riot to drive.

[@NoStringsAttached777]

Edelbrock Alloy heads for SBO engines were available 8 or more years ago from Summit Racing and others. So is the s rerelease or release of a different build for the SB?

[@scottosborne8735]

Maybe debur/stress risers and build for modest rpm? Main girdle?

[@DennisL-n6i]

Awesome stuff. You should give them a discount for going with aluminum heads. Plus çould you weld plates in the centers of the windows and then close up the windows with plates also? Plus i know what the best smallblock gm casting ever is but i got to keep it secret until i can get my hands on one. Got a 355 sbç 010 block though. Also i can explain why as well. And the olds 403 is absolutely awesome and inspiring. We got to be able to reinforce these blocks or mold new modern casting versions. Same with the other gm small locks. ( Ask me the secret and trade me one for my 355 sbç) 😊

[@stevenbelue5496]

Is the block your referring to as the best GM small block a sbc block?

[@jonesbretth]

I'm guessing this has been asked before, but what make/model is that tool box?

[@cuttersperformance]

It's an old Mastercraft maximum

[@katkilr7685]

Greatest small engine ever. Ford Coyote engine hands down.

[@user-Dr.]

The problem with that engine is that it keeps blowing up, I do track day road racing all the time, and these things blowing their cookies all over the track is far too common place, I know they're trying to run with the Camaro's, impossible.

[@pughoneycutt1986]

I always thought that GM SHOULD HAVE MADE THE OLDS SMALL BLOCK as the corporate SMALL BLOCK. As a design it's way better than the sbc but GM deliberately crippled it. DAM SHAME!!!

[@mikee2923]

Actually GM should’ve kept the Pontiac V8. 326-455 CI out of the exact same dimension block. Heads, intakes, exhaust manifolds and even engine accessory brackets all the same. Could’ve used the 400 and 455 for trucks since they were proven torque monsters. The 455 cranks were bulletproof. You could cut the 1/4” difference in the main bearing journal and put it in a 400 to make a 455. And they held up to drag racing. Chevy fans brag about making the 383 SBC. Shaving the 455 crank journals and boring a 400 .030 over gives you a 455.

[@pughoneycutt1986]

@mikee2923 I somewhat agree with you I think the Pontiac should have been the corporate 400 and 428 and the Buick 455. I also agree that the Pontiac should have been the truck engine for Chevy and GMC.

[@mikee2923]

@@pughoneycutt1986 GM eliminated the BOP 455 engines after 1976. Probably because they were downsizing their cars starting in 77 and didn’t need the big cube engines any longer. The Pontiac 455 would’ve been better suited for truck duty than the Buick 455. The Buick had the largest bore and the shortest stroke of the 3. While that may have been better for higher RPM operation, off idle torque of the Pontiac was much better which is what you want in a truck. The Pontiac also had the largest main bearings of the 3. They were overall the most durable of the 3. The 3.25” main bearings of a stock Pontiac 455 crank could have a 1/4” shaved of the main bearing journals and fitted into a 3” main 400 block and still used for racing. Yes they were that tough and they weren’t even forged.

[@pughoneycutt1986]

@@mikee2923 we are from the same side of this issue with minor disagreement. I don't think either one will get his feelings hurt.

[@mikee2923]

@ It’s all good.

[@Thumper68]

2 bolt 400sbc was the best for making big n/a power back in the day.

[@oldvsnew3400]

I'm building a 73 rocket 350 for a g body. Any heads before number 8 are great.

[@nevilleyazza7596]

The Oldmobile 403 CID was installed in California cars, due to SMOG regulations... most other cars non California cars had the Pontiac 400 CID ..

[@mikee2923]

That started with the 1977 model year. Supposedly the Pontiac V8s couldn’t pass California emissions. I think Pontiac’s 350 ceased production after the 77 model year. The 400 was done after 78. Pontiac stockpiled a number of 400s for the 10th anniversary Trans Am for 79. But you had to order a 4 speed manual to get the 400. All 79 T/As with an automatic got the Olds 403 regardless of where it was purchased.

[@scottosborne8735]

350 the hard way?

[@thundermountainatv]

Pretty sure the block that had solid webs was mistaken for the diesel block which weighed 30 pounds heavier

[@doolallyproductions7234]

GM was head in the direction of a small block with a big bore but the fuel and emissions crisis stop it. They would continue to do it in race motors and then later with the LS engines

[@w41duvernay]

ACTUALLY, GM was going to go to a Chevy SB400 on the Z/28 IN the 70s, but for some reason they went with the standard 350s instead.

[@JosephCowen-fz8vj]

Ive built five 403 olds now , nothing wrong with them , that myth of dropping cranks has very much gone away in recent years and the 403 small block is now looked for instead of gotten rid of, 1 have you personally ever seen a 403 drop a crank ? No , a 600 hp 6000 rpm well built olds will be fine . 2 LS and LT chev motors have windows in the same place . 3 they put 403 s in heavy duty applications like motor homes and so on the amount of 403s still around and driving around tells you it was not as bad a design as originally thought . As for the factory 403 head , well its 2 cc off a 455 head , has the same valves and porting on all 2 nd gen Oldsmobiles from 330 to 455 was the same including 403 , the ports are bigger on big block and the 403 intake port is slightly bigger than other small blocks ( excluding 1990 307 and 260 ) , deck a 403 head and it will flow quite well , remove stock cat and single exhaust you solve stock bad exhaust problems , as for big block heads not fitting , its exactly the same " externally " as a 350 , 330 , 403 , 400, 425 ,455 ive used 2 sets on a 403 no problems . As for bore the 403 has a bigger bore than a 500 caddy and has the biggest bore of any modern production V8 excluding the 460 ford and its only bigger by 0.009 inch , i use stock 460 ford moly rings in 403 s and file fit them as they are cheaper than 403 rings . The reason olds made the 403 bore so big was they did not want to upset the magic stroke length 3.385 inch or 86 mm the perfect stroke that you will see turn up in many many modern engines , wrx Subaru , toyota, Ferrari, Lamborghini, ford , mazda , Charles f Kettering designed the original 330 that all the small and big block olds are designed after , and that 86 mm stroke was found to be the perfect for flame propagation , the 6 degree valve angles are used all over now , chev guys get all excited going from 23 to 18 degrees , the olds has straight shot 6 deg standard , as far as port location , when chev nascar engine design needed a new port layout in the 1990 s they brought out the SB2 head for chev and it had olds port layout . The 403 was built from 1976 for 77 model run to 1979 , three years and the 403 was put in all gm brands . It was the only large V8 left that could pass emissions in 1977 . The 400 pontiacs in trans ams were left over 1975 engines , and there were 3 V8s offered in 1977/8 trans ams a standard 400 Pontiac 400 rated at 190 hp but 290 foot pounds , the 403 at 185 hp but the largest torque at 320 foot pounds and the 400 Pontiac 4 speed manual motor that was 220 hp but less torque that the 403 at 315 foot pounds so power is really torque and the 403 had the most torque at 320 . As far as olds bad head design , not so true , the 307 olds was the only GM V8 to pass emissions in 1990 with a carburettor on it , all other gm V8 s needed EFI . Thats an efficient combustion chamber. Id build a 403 any day , lighter than a 350 chev , bolt in any or most GM bodies , plenty of alloy heads around now and cheap, Edelbrock just brought out a air gap Victor intake for the 403 that really lets it flow top with fuel injection a 450 hp motor all day or more , drop a 403 were a 260 or 307 was because they look external identical, and you got a winner .

[@volvospede]

What is tee advantage of 403 compared to 455?

[@cuttersperformance]

Big Bore

[@buzzwaldron6195]

Super short stroke... lighter weight...

[@jesseduke694]

How do they put big block heads on a small block? Isn't the bore spacing different? If not, what makes it a small block? Only the ford has a bigger bore.

[@cuttersperformance]

It's not as drastically different as chevy. The big block olds engines have a similar length but are taller and wider than a small block olds

[@russellhunt5919]

Both Olds BB and SB share the same bore spacing of 4.625 with a BB deck height of 10.625 and SB 9.330 . Both have the same head bolt lay out. BB has a 3 inch main, SB has a 2.5 inch. The diesel has 3 inch main, DX diesel has .921 lifter bore and the D blocks have the std .842 lifter bores. Both diesel blocks have ample material in the main webbing for 4 bolt caps.

[@buzzwaldron6195]

He was wrong, the little Olds isn't a "short block", but a shorter deck version of all the mid block Olds engines...

[@PeggyParrow]

To the canadian Rocco in the comments,..Its NOT Zed 28, its pronounced ZEEE 28 as in Z28 . Hope this helps .

[@TheRocco28]

Sorry my friend. Nobody in Canada 🇨🇦 drives a Zee28. You drive a Zed28 north of the border.

[@cuttersperformance]

Tomato, Tom-ato

[@93_LXcpe]

​@@TheRocco28sorry not everyone of us 😂

[@user-Dr.]

It sounds like maybe soon, they may have to learn our language, naw, I think TRUMP's just joking around, neither of us really want that, our country is headed toward communism at a fast enough rate without Canada's help, they are too far left for us.

[@TheRocco28]

To the American Peggy, You do realize that Cutter Performance is located in Canada?

[@andysteele4056]

I have fantasized about this big bore babe a lot before. Not sure if it's ever been done, but what's stopping a guy from grinding down a 455 crank and makinga a 513? Here's what I came up with: olds 513 403 block +.030 mopar (icon) piston 4.382 bore 1.22 compression. height 27.3 cc dish 9.33 deck ht (+.030 ish) .050 head gasket .028 quench 455 (4.25") crank turned to bbc journals bbc stock length 6.135 rods .993 wide big end bbo heads with big valves 80cc chamber 10.5:1. It seems to me that a longer stroke crank would place less force on the main caps compared to a shorter crank at the same torque output. That many cubes in a small block would be sweet and you wouldn't have to rev it much to make good power. sorry, I'm a huge nerd. people like me annoy me.

[@tking7513]

I've heard of up to a 4.10" stroke is all that can fit. Most use a factory steel crank out of a older 400 or 425 (3.975" stroke) and turn the mains down to 2.50", the counterweights must be turned down approx 3/8" to fit also. Builds a very strong 440 easily in a diesel block. There is a 482ci built on a 403 block in an RV.

[@95Sn95]

A Question you or commenters could answer is Im due for a fresh engine in my truck it's a worn . 030 so it's done, I have a stock bore 88 roller block with decent factory internals but worn bore so it's going to get punched out .030. Should I buy one of those $1300 to $1500 eagle or scat 383 kits and reuse my ported and quite worked over 993 GM castings with big valves (and some time ahwile down the road some good cheap aluminum heads) or should I do a very budget 355 build with cheap say sealed power or Kieth black type hyper pistons and some kind of refurbished upgraded factory rods and use the original decent crank and a set of budget aluminum heads like say the skip white nkb or possibly enforcer heads. I'm thinking it may be roughly the same price where reusing my heads that don't need any work. I'm also in the process of modifying a 2nd gen Xcellerator to mount an Eaton supercharger hopefully a M112 reason for the wieand intake is the way the runners are laid out there is such a big area to mill a long rectangular slot on top it's perfect. Head wise I'd think with a blower the GM heads won't be as much of an issue flow wise but the iron thing may make a spark knock n issue but I'm not planning a lot of boost. This is going in a regular old street hotrod 92 Chevrolet c1500. I'd ask on the forums but they're terrible. Not sure if doing a draw thru carb or weld in bungs for port injection.

[@shane-222]

They needed to save the weight, there wasn’t enough power to move anything quickly.

[@user-Dr.]

True

[@SaneCayne]

Why did they cast those windows in there?? And why did they make such a big engine if they were gonna choke it down so bad? (Torque?)

[@alexvelez2141]

Weren't those engines considered a wide block not small block or big block?

[@thereluctantgearhead4544]

Small block Olds and bigblock Olds both exist. Wasn't no medium block built.

[@alexvelez2141]

@thereluctantgearhead4544 I'm referring to the 403 specifically

[@basilcarroll9729]

​@@alexvelez2141They are same size as a 260

[@russellhunt5919]

No the 403 is exactly dimensionally the same as all Olds SB's on the exterior.

[@DavidPufahl]

Sorry for the late weight sbo

[@erikcourtney1834]

I’ve always wondered if Pontiac heads will work on an oldsmobile. Or Oldsmobiles heads on a Pontiac block. They look really similar. Intake may be an issue but fabrication can solve that.

[@mikee2923]

No. Not even close.

[@croomsracingengines9265]

400 ftw

[@shaneshane1379]

Put some vortec heads on it. 😂😂😂

[@cuttersperformance]

🤘🏻

[@buzzwaldron6195]

Too much work...

[@nicksnarski5973]

Thise were smog engines from day one thin cast,not designed for hp

[@racerd9669]

Put a 455 crank in it. Easy 512 cu in

[@jamest.5001]

Pontiac pissed the bed with the 301, that engine could been a little something, especially the turbo version, if they wasn't such a pathetic casting, and anemic, I love Pontiac engines, I'm a DIE HARD,Chevy/GM guy .. I'D like to build a 400 block, with the same stroke crank as the 421, getting , 428" or possibly a longer stroke, seems the 400 had the same bore or slightly larger bore than 455", and getting a set of heads cast with high ports, raise the exhaust ports and extreme amount, 1"+ so just as well raise the intake also .500"(+/-) and kant the valves a bit 1-3°(+/-) possibly do the "twisted wedge" thing trick flow did. The intake and exhaust were at different angles, .25° - 1° or something, not slot seems the intake valve was slightly leaned to the intake . And then cast a intake to fit keeping those beautiful Pontiac valve covers, go to a over size valve multiple angle seats, bronze guides big block chevy screw- in Rocker studs. + .125"-.200" valves 2.150" intake (+/-) , and 1.890" (+/-) exhausted titanium intake inconel exhaust valve a roller cam possibly look into firing order swap like the Chevy 4-7 swap. Make a 4340 steel main girdle, and windage tray, and scraper, a custom sheet aluminum oil pan . To hold 9qts. Have a monster to put in a early 70's firebird, a 2000-6800 rpm monster, possibly with a pair of turbos, with a Holley EFI! If I were only 🤑 rich!

[@Thundarr995]

Actually, all 403 blocks are windowed. The 4 speed Firebird/Trans Ams had actual Pontiac 400 engines. Those were solid, no windows there. All the automatic cars Olds 403 engines as far as I know. I don't think they were really that bad. Have you ever seen the bottom blow outta one? Me, no.

[@mikee2923]

I’m a Pontiac nut but that’s not entirely true. Starting in 1975, the Pontiac 400 (and for some reason not the 350 or 455) had thinned the webbing that the main bearing caps threaded into to the point that the bolts protruded through the webbing. They also eliminated the dowel pin that located the main bearing caps and replaced it with a roll pin. These are the infamous 557 blocks. The first year W72 used these blocks in 1977. They brought back the old 71-74 casting 400 blocks for the 78 W72 400 over fear of warranty claims. The standard L78 400 still used the 557 blocks. The 400 ceased production after 1978. The 79 400s were all W72s set aside by Pontiac for the 79 T/A 10th anniversary. Due to the limited number available, you had to get a 4 speed with the 400. All 79 T/A automatics were Olds 403.

[@JeremyFrazelle-or1mt]

If someone wanted to get creative with some nickel welding around the mains I’m sure it could be turned into a screamer.

[@GrandPitoVic]

I had a 79' Trans Am with the Olds 403. Weak compared to today for sure

[@buckaroobonsi555]

Big bores are emissions nightmare. Once you get to about 90mm you start to have issues with complete combustion and trying to achieve emissions standards bioth cold and hot. It gets expensive fast to meet emissions. That is why so many modern engines are around 89mm bore.

[@jesseduke694]

The reason pontiac used them in the 79 TA is becouse Pontiacs 400 wouldnt meet emissions. So they must have gotton it dun better than pontiac?

[@mikee2923]

@@jesseduke694Pontiac engines only wouldn’t pass the People’s Republic of California’s emissions. They had to eliminate the Pontiac engine family because it was the biggest threat to the preferred GM enforced Chevy dominance. The last 2 real high performance non Chevy engines from GM in the malaise era were the SD 455 (73-74) and the W72 400 (77-79) both Pontiacs. At the beginning of the malaise era, all engines from the different divisions of GM made similar HP numbers. This was the precursor to “corporate” engines. Pontiac engines had the most restrictions added to them to bring them down to everyone else’s level. They had the lowest compression 7.6:1 and the secondary ports on the intake were restricted to a D shape to cut down on flow. The Pontiac 301 turbo, which was basically a failure, made more horsepower than the Corvette was making in the early 1980s. It was originally planned to be used in the 3rd generation T/A as evidenced by the identical driver’s side hood bulge on most high performance 3rd generation Firebirds that the late 2nd generation T/A had. But it was cancelled because GM certainly couldn’t have the Trans Am making more power than the ceasefire 350 Corvette. The 301 turbo was making 210 HP in 1980-81. With some development in beefing it up it’s not unreasonable to believe with some upgrades and EFI (which would’ve allowed more boost) it would’ve eclipsed 300 HP by about 1987 since the Buick 3.8 GNX engine had almost 😂 done so at that time. Something the Corvette didn’t do until the mid 90s. Just to be fair the Buick 3.8 was a piece of hot garbage until all the bugs and longevity issues were worked out. All division 455 engines were gone after 76. The 403 was the 455’s replacement. With downsizing starting in 77, GM didn’t see a need at the time to continue with anything resembling high performance. Except, of course for the Corvette. The Toronado, which always had Oldsmobile’s most powerful engine available is the only real reason Olds got to make the 403. Cadillac Eldorado based off the Toronado had its 500 chopped down to 425. The Toronado/Eldorado platform was the last car line of GM to be downsized in 1979. Both the 425 and the 403 were gone shortly after.

[@jesseduke694]

@mikee2923 That's interesting! I had a 79 TA 10th anniversary with a 403 olds & it had a factory shift kit. It wasn't really very fast. It was as far as handling curves at high speed. But it had tall gears, what exactly I couldn't tell you. But I would run it up 60 in first gear & hit second & that shift kit would slam into 2nd & it would chirp & instantly jump 10 mph. And then I would run 2nd up to 100 mph & shift into drive & it would slam & jump another 10 mph. That made it feel fast. But otherwise on dry pavement unless I power braked it, it wouldn't burn out. I had a girl freind at the time that had a 68 datson z280 with a 5 spd & it was about the same as my TA. Another guy around had a 80 or maybey 81 TA 301 turbo. It was white with a red bird & white wheels just like mine only it didn't have the shaker hood. I saw him one night & cought up to him & got beside him to try to race but he wasn't interested. He just ignored me. So I went on & left him alone. But mine wasn't really very fast. I had a 74 pontiac lamans with a pontiac 400 & it had a small aftermarket cam & 6x heads & in a straight line that car was faster than my TA I think.

[@mikee2923]

@@jesseduke694 I believe most 403 equipped T/As had like 2.73 gears if it had A/C.

[@captainrawn]

@@mikee2923 You could get 2:41 gears in a 403 equipped Trans AM regardless of the A/C. My 79 non WS6 TA had 2:41's before I changed them to 3:42's and installed a 2004R trans. My 79 10th anniversary auto 403 equipped TA had 2:73's which was standard in the 10th anniversary auto 403 cars as they were all WS6 equipped. Here is the rabbit hole: "Effective October 28 1978 the following axle ratios were used with the 403-cid cars. All non WS6 cars would have came with 2.41 axle ratio, no optional ratio was offered Federal Emissions 403-cid together with J65 front and rear disc brakes and with A/C changed from 3.23 to 2.73 403-cid together with J65 front and rear disc brakes and without A/C remains 3.23 Both axle ratios (2.73 or 3.23) require WS6 Calif Emissions (NB2) 403-cid together with J65 front and rear disc brakes and A/C has been changed from 3.23 to 2.73. WS6 package is required High Altitude Package (NA6) 403-cid together with J65 front and rear disc brakes and A/C has been changed from 3.23 to 2.73 and is available with or without WS6 403-cid together with NA6 high altitude will now be 2.73 C60 A/C is required option with NA6 High Altitude Package An August 31 1978 Pontiac memo shows 3.08 axle ratio with the NA6 option requiring A/C but was change 2.73 WS7 Option L37 301 automatic 2.73 L37 301 4-speed manual 3.08 L80 403 Federal Emissions with A/C 2.73 L80 403 Federal Emissions without A/C 3.23 L80 403 Calif Emissions 2.73 - Note C60 A/C is reqired when WS7 is ordered with 403 and NB2 Calif emissions L80 403 High Altitude 2.73 Note: WS7 was not available with the W72 400-cid engine or Y84 model Trans Ams"

[@ericwilson2585]

That sounds very similar to the 400 Chrysler B engine. A very good performance engine but completely bogged down with that lean-burn system. If you take the system off, put on a regular 4bbl carburetor and a distributor with vacuum and mechanical advance, there's a whole world of difference in how they would run. The 360 lean-burn was another one that would really wake up from the same treatment.

[@natemayo]

Put a 455 crank in

[@tking7513]

It doesn't fit, but the 425 crank can be made to fit.

[@mikee2923]

Since the customer is just looking for a good running street engine, why not make it a pure Pontiac and put a 400 in it? It would be much cheaper and wouldn’t affect collector value.

[@cuttersperformance]

The 403 was the original engine from the car when he bought it new

[@mikee2923]

@ Understood. But replacing the Olds 403 for a Pontiac 400 wouldn’t only be cheaper, better and more durable, it wouldn’t really hurt the car’s overall value. Most Pontiac enthusiasts would consider it an upgrade or how the car should’ve been built especially considering the 400 was available in that car that year. But it’s the owner’s decision. Perhaps he places value on the dare to be different philosophy. It’s certainly a better decision than putting a Chevy engine in it.

[@captainrawn]

@@mikee2923 In the Trans AM world the Olds 403 engine is perfectly acceptable when they are original to the car. Nothing cheap about building a Pontiac or Olds engine especially for performance. I have several Trans AMs that include both of those engines.

[@mikee2923]

@ You’re missing my point. I’m in no way saying the Olds 403 is unacceptable. While I realize it’s more costly to build a Pontiac or Olds engine than a small block Chevy, the Pontiac is slightly cheaper and a lot more durable than the Olds. Also that even though it was originally equipped with a 403, replacing it with a Pontiac 400, even though it’s a 79 automatic that wasn’t originally equipped with a 400, it wouldn’t hurt resale value by doing so. Most Pontiac people would consider it an upgrade. Just like replacing a 301 with a 400 or 455.

[@captainrawn]

@@mikee2923 I'd say it is subjective. There is a sizeable crowd that favors numbers matching and original to the car ahead of the alternative. A quick look at heads and intakes on Summit doesn't show much favor either way as parts prices for both engines are real close and machine work is the same for either one. I have two Pontiac 400's and a 1971 455 HO on stands in my shop at home right now. One of the 400's is the stronger 1973 block 481988 casting built to Ram Air 4 specs including an original intake, and the weaker 1978 numbers matching 557 casting block out of my Y88 TA will be finished a little tamer using 6X4 heads. Both of those 400's have upgraded eagle H beam rods in them now for good reason. We know that the stock cast Pontiac rods are a huge gamble in a high performance application and that levels the playing field a lot between the Pontiac 400 and Olds 403 short blocks in stock form. Those Olds engines were used in many vehicles including Motorhomes. My 403 stock bottom end equipped TA runs great if you scroll around I left a comment describing the build. I'd disagree that replacing a 301 non turbo with a 400 or 455 is similar to doing the same with the 403. There is a huge difference between doing that with a 301 equipped TA and a 403. The 301 is a disaster that can't be helped and a change to a 400 or 455 is welcomed more readily. The Olds 403 can be built to over 400 HP with little effort. The Pontiac 400 481988 block engines can be built to a lot higher HP no doubt. There's a 301 from my buddies 79 TA out in my back 40 under the snow that ran fine when we unloaded it there lol. He has an LS in it now.

[@95Sn95]

I'm baffled by you using the small lock moniker, everything i know about the 403 is what you said. I was under the impression olds and ponchos were all just a only block some say big block so whatever with debate. Why is this a small block if "big block" heads bolt up?I'm truly asking out of ignorance, just wondering not debating you. It's hard saying from looking at it on a video but I'm a welder/ fabricator by trade and it seems set up to weld cast it wouldn't be hard to weld fillers in the blocks windows? I noticed the hole intersects with the bore in places but there's always a work around and I know the "it's not worth it" philosophy but there's a lot of stuff that's "not worth it" but if you can do it yourself and it's a hobby things not buisness things get worth it pretty fast. Like porting "undesirable" heads, nope not worth taking to a head porter but winter time you need something cheap to do on your bench things are different. If some one with some basic porting skills could take those 403 heads and if do a pile of work to em then have em shaved to bump compression and bam half way flowing heads, with a good cam compression and intake prob good enough to swueeze prob 400hp out of it. Guides and seats is the biggie how bad are they and how much to repair it is a slippery slope. But would be a good time for bigger valves with fatter stem..?

[@cuttersperformance]

260,307, 350, 403 were all considered small block olds and used a shorter narrower block unlike pontiac that used the same block for all. I believe some guys have attempted to weld up the windows and all strength to the blocks with various levels of success. We may use the stock heads ported for this build

[@russellhunt5919]

Bill Travato built a street 403 for a good friend of mine using a 4" stroke, main girdle and 2nd gen Ebrock Olds head and Victor manifold. It made in excess of 650 hp.

[@buzzwaldron6195]

Correct term is shorter deck block, not small block/big block which goes by bore spacing...

[@approachingtarget.4503]

The solid blocks were actually the 350 diesel blocks. They have the cylinder sleeves of the 403. Open them up and swap out the crank. In combination with the 425 crank, you come out to a true 442 ci small block olds. The earliest version was a prototype in 1970 on the w-35. Hemi head model. It was also reserved for the Hurst 442 in 78. Black/white and gold addition. The 403 was also produced with the turbo version. A true 6.6 turbo. You keep saying it wasn't a race style engine. It is just a smaller version of the olds 455 H.0. It held its own among any of the factory cars. Without spinning it to the moon. Running 14.0 1/4mile in a vehicle that weighs over 4000lbs. Faster than the 454 chevy Malibu. The solid block 403 was also equipped in the 6.6 pontiac can am.

[@Patrick-xd8jv]

The 403 was never a factory turbo engine

[@russellhunt5919]

The diesel had a bore of 4.057 and if you are extremely lucky you may find one of the DX blocks that can be bored to 4.250 but it's thin, very thin. Those blocks are not siamese. Most have a safe bore or 4.185 . The DX blocks are the later of the Olds diesel, D blocks being the first iteration of the Olds diesel.

[@100amps]

Yeah, it coulda been a contender. Geeze, 185 hp is weak for that size engine, even in the smog years. That was about the lowest hp a 350 sbc had at its worst. I think.

[@buzzwaldron6195]

The SBC 400" had 175 HP in most cars from 1974 on... The SBC 350" in '75 Monzas for California rated... grab your chair... 125 net HP !!!

[@100amps]

@buzzwaldron6195 Cool info. 1874 huh? 😎 I know what you meant.

[@patrickm.8425]

What's with an Olds engine in a Pontiac car? Surely the Pontiac 400 would have been a better choice, and can make plenty over 400hp without worry!

[@buzzwaldron6195]

Olds engines burned cleaner and were put into all kinds of cars for that reason...

[@mikee2923]

Also Pontiac’s engines were the biggest threat to the GM supported Chevy dominance. Had been since the late 50s. GM would never allow a mainstream Pontiac to outhorse the Corvette.

[@captainrawn]

The correct answer to this question is.... Starting in 1978 the olds 403 was used in the California cars with an automatic only as the 400 Pontiac didn't meet emissions requirements there but it was available elsewhere. In 1979 all automatic cars got the 403 regardless of location and the 400 Pontiac was only available with a W72 performance option and a 4 speed. If you lived in California you had to get one of those from out of State. Also the 78 and 79 W72 400 220 HP engines used the better XX block casting. Run of the mill 180 HP L78 400s used the weaker 557 block casting in 1977 and 1978 but this engine was not available in 1979.

[@mikee2923]

@@captainrawn Pretty sure it started in 77. Burt Reynolds was promised a new T/A every year for life for Smokey and the Bandit. But he only got 1. It was a 1977 that had an Olds 403 in it with an automatic. Why? Because he lived in California at the time. If Burt Reynolds wasn’t getting a Pontiac 400 in California, nobody else was either. Also the Pontiac Grand Prix in 1977 the base engine in federal emissions areas was the Pontiac 301. In California and high altitude areas the base engine was an Olds 350. The Olds 403 was optional. When they ran out of Olds 350s, some received small block Chevy 350s. The Pontiac 350 and 400 were still optional in the federal emissions areas. The other odd thing was the turbo 400 transmission was installed in all federal emissions areas even with the 301. While the non Pontiac engine equipped GPs had the turbo 350. After 1976, no Pontiac engines were available in California. The 1977 Can Am was also equipped with the W72 400 in federal emissions areas while California got the Olds 403. Not sure what transmission the 403 powered Can Ams got.

[@captainrawn]

@@mikee2923 Ahh yes you are right Mike it started in the 77 TA's in California. In my haste to reply I goofed on that. Thanks for making the correction! Cheers

[@jcnpresser]

Some of the stupid stuff done to try and get fuel economy. What’s the block weigh? Curious.

[@whaddayawant2197]

Look up the videos on the 350 chevy should have built. Videos and dyno on that. Basically same idea big bore smaller stroke. Very flat tourque curve.

[@Christopher-re2hl]

Ford 460 has the same bore

[@cuttersperformance]

That's a big block

[@taomicioli]

And windowed bottomend..... shite

[@josephjordan4977]

Contemplating about building an Olds 403 with the Speedmaster aluminum heads, somewhat sceptical about the windowed mains, any helpful advice is greatly appreciated.

[@thereluctantgearhead4544]

​@@josephjordan4977Do it, they aren't as fragile as most dip shits believe. I've run 11s with one with no girdle and stock main bolts. Used a 1966 forged 330 crank tho.

[@OSRn77e]

I wouldn’t put that in my wheel barrel.. chunk it and use a 455 it’s twice the engine and horsepower

[@cuttersperformance]

Do you have a 455 powered wheel barrel ?

[@OSRn77e]

@ 😂