REBUILDING A 350 SBC WITH MORE PERFORMANCE FOR LESS MONEY!! How carbon build up wiped it out!

[@Dogboy1960]

350 build on a budget: This is something I've done twice over the years. A basic, healthy 350 with flat top pistons as my starting point. I've used a Flat lifter cam, Comp 280 magnum, and a set of 195cc budget aluminum heads, an Edelbrock air gap topped with a 750 Holley. You can use either 750 Mechanical or Vacuum Carb. I'd do the Double pump if occasional Drag strip use was intended and I'd definitely run the Vacuum carb is this was a street only situation. This combination is cheap to build and will produce near 400HP and still have plenty of mid range power. It's an old school thought process that was big back when cars and trucks with still healthy short blocks were everywhere. This was a kick ass combo for the guy who just slap on heads, cam and intake over the weekend without pulling his good running 350. In the 1990s I first did this with a set of vorec iron heads that produced something in the neighborhood of 350HP. More recently (12 years ago it was aluminum cheapo basic heads that made the most sense because they just outflow all the Chevy Iron including the best of breed Vortecs. Saving the weight is pretty cool too. This is really basic and cheap though. If I were to do it again (tough decision with all the great crate engines available) I'd spend the few extra bucks and do a 383 stroke and roller cam. The extra torque found in the extra cubic inches and the HP improvement found in the roller cam profiles is worth it, IMO. But it will eliminate any cost savings found in leaving the short block as it is and the roller cam in an older block is substantially more expensive than going with the flat lifter cam. The payoff though is a lot more power. 383s with roller cams can easily make 450HP and a boat load more torque everywhere on the curve.

[@goldsgarage8236]

Thanks Dogboy, all good comments and valuable information. AG

[@Dogboy1960]

@@goldsgarage8236 Thanks I can get a little "wood on the ball" when speaking to the basics. I like your channel for the more in-depth stuff that you pass on. It's well beyond my much more limited experience with the SBC. Those of us with an interest seem to all have some grey hair on head if not a full head of it. LS swaps are everywhere and I get why but I still love the old school pre-computer builds best. Lately I'm starting to better understand those older Ford "flat head" builders still around and doing their thing in the 1960s and 70s.

[@greggc8088]

An ambulance came to pick me up when I had a wreck on my KLR 650 and as he loaded me up I asked him "are you taking me to the hospital?" Driver said "Nope, we're taking you to the KZbin comment section where all the experts are." 😂😂 Couldn't resist the joke. Glad you enjoy our comments.

[@goldsgarage8236]

Thanks Gregg, I really enjoyed this comment for sure. AG

[@GrandPitoVic]

@greggc8088 ROFLMFAO!!!! Great one lol.

[@GrandPitoVic]

Great info sir!!! My aunt had a 70 something Buick Electra 225 and that thi g got to where is would run on so badly. It finally cracked the distribution. What a boat!!! Big Ole 4 door. That ugly green they had back in the middle ish 70s lol. I put a fuel pump in it when I was 12 years old because my uncle pulled his back and couldn't do it. We were stuck in a Montgomery Wards parking lot and it got dark on us. He walked me through it and that set me on the road to being a gear head. Everyone has that story that set them on that path lol.

[@goldsgarage8236]

That is an awesome story. The satisfaction of accomplishing something like that when you were 12 years old and you were hooked. Thanks for sharing.AG

[@shadvan9494]

If the engine was running on and dieseling, then it was most likely detonating under load. it doesn't always make a pinging noise. TRW had several different business divisions, everything from automotive to Aerospace and even Credit reporting. they made automotive parts for all the major automotive companies, they made the Pioneer series of satellites, and Delta class launch rockets, the first US ICBM and the Titan missiles systems. TRW was acquired by Northrop-Grumman in 2002 for its aerospace assets. and the other divisions were sold off. TRW credit became Experion, Federal Mogul acquired the piston design and manufacturing division at some point and is still making the TRW pistons under their Sealed Power / Speed Pro Brand names. they even use a similar part number to the old TRW pistons. the only difference is now they add an anti-friction coating to the skirt of the piston. The TRW pistons i used in my 1971 Camaro SS 369 back in 1998 were L2240N, the Speed Pro part number is L2240NF the only difference is the coating they use on the piston skirts. Other than that, it is the same piston.

[@goldsgarage8236]

Thanks for all the great information Shadvan. I lost track of TRW a long time ago, so nice to learn how history has evolved and they are now Sealed Power. AG

[@chuckmiddaugh7908]

Great to see your channel grow. I'm not consultant grade, cause I'm just a Toyota tech from Kalamazoo. I watch to live my engine building dreams vicariously. Dont hesitate to tell old man stories here. We like your content because its real not because it's perfectly curated.

[@goldsgarage8236]

Very nice compliment Chuck, thanks so much for taking the time. I was in Kalamazoo once, I took a weekend course on circle track chassis set up from Randy Sweet.AG

[@CULT539]

If those heads he has are worth a lot of money, maybe he could consider selling them and upgrading to a budget set of aluminum heads? Save weight and run more compression without the worry for detonation. Once you start replacing things it’s easy to go deep in the rabbit hole quick. I dunno how much low buck SBC heads even are for us Canadians. The exchange rate is killing us.

[@goldsgarage8236]

That may be a consideration. With the cast iron heads, I am planning to use a .015" steel shim type head gasket to get the quench to .045" . If we do use aluminum heads, that is not an option and we would have to deck the block. It gets complicated. AG

[@shane-222]

@@goldsgarage8236 agreed Al, Steel shim is best value… but how much power does he want?

[@rgmenard2578]

17:29 Very interesting to hear you raced C/MP in the past. I’m from London Ontario (currently living in Scottsdale, Arizona) and until 2014 raced a Fred Smith Olds Ciera in C/MS (C Modified Stock). Thanks for the informative You Tube videos and give my best to Bill Little. Ray Menard

[@goldsgarage8236]

Thanks Ray, I will say hello to Bill for you. I didn't live in London during the C/MP days. Enjoy Scottsdale.AG

[@pockets5628]

Dieseling starts with not having enough timing at idle for the camshaft the engine has. Insufficient timing advance then requires the carb throttle blades to be open further than they should be to obtain and idle. On a holley carb, and a carter/edelbrock, this causes the transfer slots to over expose, which the engine then draws in more fuel than it should at idle. A tell tale sign is the mixture screws are in responsive. The insufficient timing and added fuel then causes carbon build up, but also higher combustion chamber temps, and exhaust temps. The when you turn the ignition off, there is enough heat in the chamber to keep igniting the extra fuel and air from the throttle blades being open too far. I have fixed several Dieseling engines by reducing the amount of centrifugal advance in the distributor, increasing the initial advance to what the engine should have based on the cam overlap/lsa/duration at .050” and cubic inch, then resetting the throttle blades/idle, and lastly idle mixture. You can also use vacuum advance on full manifold vacuum for the increased timing advance at idle, as long as the engine makes enough vacuum to pull the vacuum cannister in all the way, and hold it there at idle. Otherwise you will have varying timing, and unstable idle. It also must be able to keep the vacuum cannister pulled in at idle in gear if an auto trans vehicle.

[@goldsgarage8236]

Thanks Pockets, and for anyone watching, I think this is an accurate description of dieseling, and the correct method to remedy the problem. Thanks for very well written technical advice.AG

[@pockets5628]

@@goldsgarage8236welcome!

[@stevenbarnett2169]

The next engine I rebuild will have a new complete rotating assembly. The machine shops are getting overpriced and I always have a problem.

[@goldsgarage8236]

Thanks Steve, they still have lots of work machining the block.AG

[@dondotterer24]

I have also found HEI stock distributors that went 45 deg. Total with even 12 initial. I welded the slots in the mechanical advance for a HP application.

[@MarcusSandoval-kx2th]

Hey can you explain degrees of timing ...all I know is what we see on the timing tab ..what's this 30 degrees advance I hear when dyno tuning in vids

[@goldsgarage8236]

Thanks for the suggestion Marcus, I will cover that on a future video.AG

[@dondotterer24]

@@MarcusSandoval-kx2th they are talking about the total timing used weather the distutor is locked out or the total with one that is using mechanical advance + the degrees set at initial idle

[@MarcusSandoval-kx2th]

@dondotterer24 yeah but how are they doing that??? All I know is the few degrees on the timing tab which is what 8 or 10 max?

[@dondotterer24]

@@MarcusSandoval-kx2th you have to have a advance timing light or put a degree tape on the balancer.

[@waltercarpenter2439]

I am amazed of some of the stuff we used to do and get by with it back in the day. I laugh at some of the things I did back then.

[@goldsgarage8236]

Thanks Walter, i am sure we would enjoy sharing "war stories." AG

[@GregMargraff]

The book "Chevrolet by the Numbers"shows 2 types of pistons in the early 70's. 358s camaros. My '74 lt camaro came with a 2 bbl with dished while the corvette and hp camaros had theTRW's. These were rated at 265 hp net. I'm thinking it must have been a Z 28. I'm suprised that the bores are that good! I'm interested in seeing those heads! I assume they have studs and guides.plates. Hope you dyno it with a proper head gasket just to see what kind of power it makes. I would be thinking it came with a q-jet!

[@goldsgarage8236]

Thanks for the comments Greg. This engine would have originally come with dished pistons also. Yes the 292 heads have studs and guide plates. AG

[@WVXL64]

Auto ignition from carbon makes sense. It will hammer the bearings and rings/ring lands. The carbon build up is probably from a combination of running too rich, and not running enough timing, especially at idle.

[@goldsgarage8236]

Correct. Thanks for commenting Keith.AG

[@JudgeMeNotLeMans]

Couple thoughts on the carbon build up. Over fueling from worn components or improper float setting or jetting too rich. If you have the carb that could be verified. Other possibilities that could cause detonation are sharp edges in the combustion chambers although less likely if all the cylinders are showing carbon buildup. Lastly the PCV valve sucking oil into the intake and making its way into the combustion chamber causing the buildup and the result could be the running on symptoms.

[@goldsgarage8236]

Those are all possible causes and good advice Judge. Once the engine is complete, we will pay attention to the tune for sure.AG

[@yarrdayarrdayarrda]

Bear in mind that aftermarket pistons have the required clearance machined into them, even standard sized. So you have a piston that wants .003" clearance, and will have that clearance, but when you add the .002" that your block currently has, now you have .005" piston to wall clearance. Since you're doing the job well, may as well make it perfect, get oversize pistons for the job.

[@goldsgarage8236]

Thanks Yarrda. Yes, I was concerned about that, so today my customer Paul and i made a decision to bore the engine .030" and install a new rotating assembly. We have come a long way from a minimal repair. Thanks for your help.AG

[@mikes9939]

I've been following this engine and I have some info for you. I am an older Chevy guy like you and have worked with these engines since the '60's. I currently have a '76 Corvette L 82 car and I have gone through the engine. I have a 3970010 4 bolt block with the high nickel and high tin markings under the timing cover. Look for 010 and 020 cast in the front of the block. I also have the1182 steel crank and the famous pink rods that were used back then. Mine also has the same forged TRW piston as you do. Those pistons were used in all the L82 engines that were used in the '71-77 Z28 Camaros and L82 Corvettes. All these engines had these very good parts and Chevy even sold this as a short block for several years. I re-used the rods and pistons because the engine had 68000 miles 5 years ago when I rebuilt it. It is still standard bore because the high nickel blocks were harder and wore less. Those flat top pistons are very similar to the 11-1 domed pistons used in the 1970 LT-1 engines in that they both have the long valve relief. Chevy used this because it was believed that it helped breathing during overlap when both valves are open slightly and permitted mixture to move across the piston more easily. Those pistons are also made with the very desirable VMS 75 alloy that TRW pioneered and was so good that Bill Jenkins preferred it to the 2618 alloy that was and is common in aftermarket pistons. It was possible to fit them closer to the bore size and have less rock and noise with better ring wear. They also have holes around them for oil drainback instead of slots that weaken a piston. In short they were a very good choice for those engines and shows that Chevrolet was concerned with durability. Chevy also had them about .025 down the hole so you should then use the factory steel shim head gasket which is about .015 and therefore will end up with a clearance spec of .040 which a perfect to eliminate detonation. Bill Jenkins also used the factory steel shim gaskets on his engines. If you cut the block and get the piston at zero deck then you can a Felpro composition gasket at .039 and have a correct clearance spec. Never use a thick gasket with the factory .025 deck height, you will end up at .070 or so and have detonation problems for sure. The factory steel shim gaskets are great and should always be used with iron heads, not aluminum. Also no retorque is required and they never did that on the assembly line. I would also drill the hole on the block deck between the center two cylinders on each size a outlined in the Felpro head gasket instructions. It will aid cooling at the spot where the center exhaust ports are and reduce heat there. Some block were drilled and others not. Mine is but I have drilled others that were not. It's the rusty spot between the center cylinders on your block, I can see it in the videos. Usually a 9/16 is correct but Felpro shows you. Another small item was Chevy used large 8 inch thick harmonic balancers on the engines with steel cranks as in all the hi-perf stuff. Steel cranks a more flexible than iron cranks that simply crack but are more rigid. Steel is ultimately stronger but has more harmonics that must be controlled. Chevy was always looking out for back then. Good luck and I'll be following you.

[@goldsgarage8236]

Thanks Mike for so much well thought out detailed and valuable information. Most of it is consistent with my thinking and present practices and procedures, but drilling the 9/16" holes is new to me. I will look into it. We are always learning. Thanks for taking your valuable time.AG

[@r.joseph8911]

“Gold’s….Scraaaage”

[@OgamiItto70]

O-jeez. You should reelly say yer sory; that wasn't very polite of you.

[@shane-222]

For a high value high performance build, stroker crank, aluminum heads and tall compression height pistons to make a good quench gap without decking the block. Still no machine shop.

[@goldsgarage8236]

That is a viable option, based on availability of tall compression height pistons. Thanks Shane. AG

[@shane-222]

@goldsgarage8236 it’s the same piston, they drill the wrist pin hole a few thousands offset, DSS should accommodate without issue. There’s probably even stocked pistons available once you know what compression height you want.

[@waltercarpenter2439]

also to hot of a spark plug can cause engine run on. I like your discussions

[@goldsgarage8236]

For sure, because it increases combustion temperatures. AG

[@CULT539]

You can, and we still do cut pistons. A friend has a drag car tube chassis, tubbed big tire car with a basically stock lq9 6.0 iron block LS out of an Escalade. We fly cut the pistons with a tool that you can buy for LS engines. It has a big cam 706 heads with bigger valves and a big cog drive Paxton supercharger. It runs 8’s in the 1/4 after 5 years the only thing it’ll do is bend a connecting rod once in a while. Just take it out and put another used one back in it. NEVER a problem with the pistons after cutting a valve relief. So some of us still do the same thing we learned from guys like Allen that drag raced many years ago.

[@goldsgarage8236]

Thanks CULT. I think the difference is that we did it over the fender with the engine in the car. AG

[@krisjones1286]

I had a 9:1 stroker that had a cracked vacuum hose that would "diesel". Fixed the leak and it went away. Edelbrock carb, weiand intake.

[@goldsgarage8236]

good info, I can see that happening. Thanks Kris.AG

[@stevenbarnett2169]

When I worked on these engines they had an anti diesel switch.

[@alleyoop1234]

A solenoid at the front of the carb!

[@stevenbarnett2169]

That is correct.

[@goldsgarage8236]

Thanks guys, yes i remember now, it collapsed when the engine was shut off, closing the throttle plates.AG

[@gordongrimes2797]

yes good ol days I watched a guy do valve clearance with a body grinder pistons in the block, needless to say it slowed down, lol hum? nick's gerage just did the clearance on a 383 chrysler with a cutter valve using an old head looked good and worked great. storys are good 👌

[@goldsgarage8236]

Thanks Gordon, I will check out Nick's video.AG

[@shane-222]

Make sure the owner is running enough timing to burn off the carbon this time! There had to be detonation from the pre-ignition causing the bearing failure. The “quench” is not actually quench at that wide of a gap and could explain the lack of pitting.

[@goldsgarage8236]

great point Shane, we will be sure to pay some attention to the tune once its back together. AG

[@r.joseph8911]

timing is a big factor in whether an engine diesels or not.

[@goldsgarage8236]

For sure, thanks for commenting R. AG

[@dondotterer24]

I always round off the sharp edges on the valve releafs

[@goldsgarage8236]

Good advice to prevent hot spots, thanks Don. AG

[@pauldhiman8369]

Awesome

[@goldsgarage8236]

Thanks Paul.AG

[@waynewrite1497]

Just subscribed, been watching on and off for a while.. I think you guys should make it a 383.. very simple, plus more cubes....Thx!!

[@goldsgarage8236]

Thanks so much for subscribing Wayne. Lots of content to come.AG

[@Orvillefpike]

I read, on other KZbin channels, that not enough quench can cause detonation.

[@goldsgarage8236]

Thanks Orville. If you mean not enough as in less than .040"? If the piston hits the head detonation will be the least of their problems. AG

[@Orvillefpike]

@@goldsgarage8236 Is the quench on this motor less than .040? It thought that it was much more.

[@anglia427]

The good old days before unleaded gas had lots of carbon build-up, the old trick was a water spray bottle mist down the carb while revving the motor worked well.

[@jdandboo]

It still works. But in the old days- I've stood over quite a few carbs with a bottle of water !!

[@PatandDoopypoopy]

​@jdandboo I'm 56. I'm of era to learn this trick. Works fantastic and costs nothing fir supplies.

[@goldsgarage8236]

Thanks for the info guys, I have heard of that, but never tried it.AG

[@kevink8481]

Oh yes. My brother installed an 850 cfm carb on a stock 77 CJ 5 304 with side pipes. I put a whole bottle of water down the carb while running at about 4 grand, just enough to load it up. Blew chunks out of the side pipes

[@Boss-mo3zf]

Please have your mic closer . Too quiet for the hard of hearing thank you .

[@doomman700]

I am betting it detonated under load as well as the run on. Check the curve in the distributor being used.

[@goldsgarage8236]

Thanks Doomman, for sure we will pay attention to the tune to make sure it doesn't happen again. AG

[@pamdunn8454]

on the 409 it wouldn't be numbers matching for 1962 it would be period correct

[@goldsgarage8236]

That is correct, thanks Pam.AG

[@Gary65-fl4rz]

If you’re looking to put in a full rotating assembly, why not go with a stroker crank and get some more displacement. The increase in cost would be minimal

[@goldsgarage8236]

Thanks Gary, that seems to be the popular thinking. AG

[@Gregoman89]

I could really use some advice how to proceed with my aluminum headed 355 I need to rebuild. Most power on a budget style

[@goldsgarage8236]

Thanks Greg. There are many good videos about budget builds, some are Gold's Garage. Also check out Cutters Performance who has good budget videos. If you have questions, please post them and i will try to answer for you.AG

[@dondotterer24]

Are you going to have it balanced?

[@goldsgarage8236]

Not sure yet. Some rotating assemblies come balanced. We will see what is available. AG

[@MarcusSandoval-kx2th]

Ive got a basically new GM 350 short block from about 1998 and it came with dished pistons and i wanna install flat tops but hate the idea of using the original press fit pins if i go aftermarket rods with floating pins will i need to have balanced ? 😢

[@alleyoop1234]

It will still be balanced, but to a slightly different balance factor.

[@goldsgarage8236]

I agree with Alleyoop Marcus, you will be fine.AG

[@MarcusSandoval-kx2th]

@goldsgarage8236 so the new pistons and rods won't require balancing???

[@Trustyconsultinggroup]

Another great video

[@goldsgarage8236]

Thanks again for watching and commenting Trusty. AG

[@39impala]

is the balancer not spun and 0* at tdc?

[@goldsgarage8236]

Thanks, I will check it out. AG

[@davidreed6070]

That sure does look like the l82 piston to me.

[@goldsgarage8236]

Correct David, AG

[@JamesBower-l9d]

A friend of mine told me about the value trick with the cutting edge! He’s 74 years old…

[@CULT539]

We still do it and I’m half Allen’s age…. You can buy the cutting tool for LS engines.

[@goldsgarage8236]

Thanks James. I was surprised to hear that. Not sure if I would recommend doing it over the fender with the engine in the car.AG

[@alleyoop1234]

Those pistons appear to be the exact same as what came in a 1972 LT1, but surely would never been in a 2bbl 350 originally.

[@goldsgarage8236]

For sure Alleyoop. The block was born in a 2barrell 350, but pretty sure the pistons were installed whenever this engine was rebuilt.AG

[@mikasantos3774]

Waiting for that dyno vid from the last small block

[@goldsgarage8236]

Thanks Mike, it was published on my channel on Nov 10, please check it out. AG

[@mikasantos3774]

@goldsgarage8236 awesome thanks I'll check it out

[@shawnbins203]

If you’re going buy a rotating assembly- you might as well go 383 or 396.

[@goldsgarage8236]

Thanks Shawn, yes, but we started with a minimal repair, where does this end? AG

[@shawnbins203]

My thought was IF you’re buying a rotating assembly- (crank , rods and pistons) it’s basically the same price to get a stroker assembly. But yes- you’re going to have time in clearance grinding on the block.

[@dannydurham5716]

I need one TRW 3927172 and one "O" stamped rod if anyone has one Love the car stories

[@goldsgarage8236]

Thanks Danny, lots more to come! .Good luck on your search. AG

[@jamescereda2628]

Keep the pistons and rods,new crank. And you got a runner! That's a low-budget build! It will last if the owner doesn't RPM it every day!

[@goldsgarage8236]

thanks for your input and suggestion James.AG

[@johngibson3837]

Hey up mate good video but don't understand why you said of having to take pistons to your machine shop to remove pins just doesn't make any sense to me

[@goldsgarage8236]

Thanks for the comment John. If I do this, I will need the pistons removed without damage so that I can reuse them. I know there are home methods to do this, but I have always just trusted my MC for this process.AG

[@johngibson3837]

@goldsgarage8236 don't understand mate, piston pins either tap or lightly pressed out obviously after removing c clips

[@richardfawthrop8056]

Bore it. If two cylinders are large someone probably honed it to remove rust marks.

[@goldsgarage8236]

Thanks Richard.AG

[@r.joseph8911]

Zed? Zed’s DEAD.

[@goldsgarage8236]

Got it!.AG

[@r.joseph8911]

“Z”-28

[@goldsgarage8236]

Got it! Thanks AG

[@kevinrandall8327]

Yap yap yap yap get to the point I’m going to sleep listening tp you

[@michaelkienhofer6394]

Nick,s Garage did just that procedure, "Piston to Valve clearance"

[@goldsgarage8236]

Thanks for the info Michael. I will check it out. AG