Did We Find The Smoking Gun Behind Our Slant Six's Lazy Launches?

Getting the power out of the leaning tower in our Plan Z Dart is proving to be a bit of a challenge.
We've been working out the bugs one by one and have been making progress, but still the engine is producing far less power than it should on paper.
Could it be that we've been overlooking one of these engines unique design features and actually slowing ourselves down by applying V8 logic to a situation where it doesn't apply?
Here's what we've found and how we plan on drastically reducing the cars 60 foot numbers.
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[@86AW11]

All these years later and Tony learns that fuel burns better when atomized

[@anthonygeiss3708]

This is a testament to what old school hot rodders faced every part was an experiment and had to be tested on the track.

[@FerdinandAkin]

Build a shroud around the headers that directs the heat to rise up to the intake manifold. Put a fresh air pipe from the grill into the shroud. When the car is sitting still, heat from the headers warms the intake, but when the car is moving the fresh air pipe blows the excess heat away from the intake and carb.

[@zagstrukk]

Also remember that David Vizard mentioned that a drop leg booster is best when you have an unheated intake manifold. It assists with vaporizing the fuel better than the other boosters.

[@indianaslim4971]

Makes perfect sense to me, anyone who's worked on air cooled VW's is familiar with the heat riser tube clogging up and the intake getting cold enough to see a waterfall of condensation resulting in craptation.

[@MrTheHillfolk]

Heh I'm pretty sure I seen em getting frosty on the outside before

[@indianaslim4971]

@@MrTheHillfolk it's a common problem on VW's, when I switched from bodywork to mechanics I worked at a shop that specialized in VW and can't count how many times I tried the Roto Rooter thing to clear out the tube.

[@EdgarsLS]

You should put in annular boosters in the carburator, it makes a much finer fuel mist and helps with atomization, not requiring as much heat in the intake

[@shoominati23]

The Max Wedge cars said in the Manual to warm them up for 5 minutes and then switch them off for a minute or 2 before a run to allow the engine to heat soak - maybe that might be worth a try

[@hotrodray6802]

I forgot that.👍 Been 10 yr since I had a MW or Hemi wide spread carb manifolds.

[@TheUllrichj]

I think you are on the right track. Get the launch straight and then the top end. Efficient burning of fuel by better atomization as opposed to dumping more liquid is the way to go.

[@brucew13]

Attach a temp sensor to the intake manifold, monitor it in the car, work out when the intake is at the temp it works best, then when at track get it to that temp before you race.

[@ssnerd583]

that is what I would do....test it and see!!!

[@steveanderson9290]

Agreed. Step one, gather accurate data. This is actually a neat problem...all kinds of ways to skin this cat.

[@stuckinmygarage6220]

I like 👍

[@michax175]

I can never get enough of PLAN Z lol

[@mastertigh-8617]

👍

[@MegaMotionStudios]

Never been a slant guy but this is my favorite project on the channel

[@jamescameron6819]

Same here man. I love this crazy no sane man would do it kind of build.

[@Str8sixfan]

It's definitely a diZeeeze you can't shake

[@charleselertii6187]

Tony, watch out for you draining the battery voltage down with the long idle/run time with electric fuel pump and ignition while you are trying to heat it up. Also, maybe a temporary sheet metal fab to put in place to capture/direct exhaust header heat to the intake manifold. Cheers, Chuck in Florida.

[@johnsengers4265]

Swap in an alternator from a 94 vette, direct bolt on and connector just plugs in. Charges twice the amps at idle than stock 84 alternator, put one on my 86, and at stop light, 8 brake lights, air cond, radio with amp, charges 13.1 volts

[@biffman1212]

"Dan, He/Him." LOL! I almost fell out my chair on that one!

[@rong4189]

Have Uncle Kathy heat the underside of the intake real quick with a mapp gas torch, after the burnout, before you stage lol.

[@2000freefuel]

yeah I was thinking the same thing, but maybe setting it up so it can be operated from the drivers seat.

[@chrisallmond6867]

Sounds like a great way to start a fire

[@zoldcarsntrucks]

Some fords have a factory heated carburetor spacer that you may want to try

[@spasticnapjerk]

Love those STP stickers, we used to hit up every place we stopped for gas in the early 70s

[@josephtome9600]

They used to sell a heat riser kit to restore the function after headers were added. A clamp on air heater for one header tube supplied air to the stock air cleaner intake. Take it from there. A solution to the winter problem of stumble off-idle after warmup.

[@MrBiggerdaddio]

Sounds like the more you drive it the better it will drive, h3ll ya brother!

[@Broken_Yugo]

Along the same lines as "most (suspected) fuel problems are ignition problems", most actual fuel problems are atomization issues. This engine would likely benefit from the more modern booster designs if they aren't already installed.

[@legros731]

It will benefit way more from fuel injection all these problem will go away in a instant a the wonder of delivering the fuel right where its needed not one foot away and praying it go equally to all cylinder

[@waynebuzzell2483]

Just added. Added posted garage and no added. Added anything.

[@legros731]

@@waynebuzzell2483 ok but i think you didn't added enough

[@lasskinn474]

@@legros731 well yeah it would make a lot more on port injection, probably. buy you know what would be fun, counting out a megasquirt or whatever. a bit of of intake header on every intake port and have side draft webers on that then. well, just an afr data logger would have clued into what was the problem tho, no reason why one couldn't still take use of some technology when using carbs

[@legros731]

@@lasskinn474 sure a wideband o2 sensor like the aem one that are stand-alone would make this process way easier 3 weber side draft or 6 41mm fcr dirtbike carb could be cool and sound fire i made 50 hp on my single cylinder (510cc)4 wheeler with one 39mm fcr so 6 of them should be good for 300hp

[@johnpublic6582]

Also, there is a carb heater on piston airplane engines. You leave it off most of the time for better power, but when you go from cruise or climb power to idle that cooling effect of the gas vaporizing will form ice from humidity in the boosters and kill the engine, so at every throttle back you put the carb heat on first. Not normally a problem in cars because of how the heat transfers, and cars don't usually sit at 80% power for an hour and then drop back to idle.

[@JSki-kb8vf]

And the altitude has a bit to do with it...

[@tbthedozer]

Old 80’s Hondas had heaters in their carburetors too because the would ice up on high humidity days..I even found a carb heater on a kid’s Yamaha dirt bike.🤷‍♂️

[@Broken_Yugo]

Maybe bolt a waterblock to the manifold heat pad and hook it to the heater loop?

[@vornice7604]

an intake with a lot more downdraft would help that problem a lot I bet, the floor of that intake is so flat your fuel is smacking that floor and falling out of suspension, the heat is remedying that problem. i think the fact that the engine is only sucking from 3 of the 4 plenum walls and all to one side is a factor aswell

[@heftyjo2893]

Maybe the hot side of a Peltier Module glued to the bottom of the manifold. I think they get up to nearly 200 degrees F. which would probably be an optimal manifold temp and will run on 12v systems.

[@lasskinn474]

you'd need some control on it. cheaper and easier to just use resistors or nichrome wire if going electric heater route. they got a delta temp and you'd need to have a sink on the cold side of the tec or else it would just sit with the cold side on ice and not heating the hot side as much(still heating it tho).

[@ScottKenny1978]

David Vizard did some games with a carburetor like that, he ended up designing a special atomizer nozzle for the fuel squirters.

[@thomasknobbe4472]

Makes good sense to me. The Chevy Stovebolt guys who run separate intake and exhaust manifolds deal with this problem by bolting a "heat plate" to the the bottom of the intake manifold under the carburetor, through which they circulate hot coolant in order to keep the manifold warm enough that the fuel does not puddle out.

[@americanpatrol4603]

I've got one under a 454 TBI. Works great and it would be easy to put on and just as easy to get back off if it doesn't work for him.

[@napoliansolo7865]

I didn't know about the heat plate thing, but that's what I was thinking.

[@domturchi]

I was thinking the same thing.

[@georgejr2640]

Maybe even a heat shield on top of the manifold to capture heat from going between the runnser, instead of shielding.

[@drmopar6122]

Well, I said nitro, but I think some direct port methanol mechanical fuel injection would work well.

[@drmopar6122]

I’m for magneto ignition driven off the front of the cam, Hilborn mechanical fuel injection with a spun fuel tank full of methanol mounted to the front of the car, and deleting the existing fuel tank, pump, lines, and water pump along with the rest of the cooling system for more weight reduction. I’m pretty confident you could cool it with the volume of methanol you could pour into it like the truck and tractor pulling racers do. Might not be budget friendly or completely in the spirit of the channel, but I bet I’m not the only one who would like to see someone do it!

[@notmybleepingbike4812]

Thanks for sharing your thought process when troubleshooting issues. I don’t think many people would think about heat being needed in the manifold. You were basically applying a bandaid to the problem with the way you launched. Yep. I’m thinking a heat riser from the headers. Just keep it simple

[@bertramlrezenet9311]

In a previous video you commented you were not warming up the engine before your run. My advice was to get the engine to near operating temp or when the thermostat opens (if you're running one). In addition, before I'd lean out the carburetor, I would build a shroud under the intake, in order to trap some of the heat from the headers. That should help the carburetor vaporize the fuel, since you don't have a crossover passage or heat stove under the carburetor. Keep in mind, you're not running an OEM intake manifold, which is designed to help achieve a fuel droplet size of 6 microns or less.

[@punch_bowl_turd3005]

"he/ him" LMAO!

[@tommycook9620]

😂😂

[@ameliaroberts3945]

Could you use the heater hose from the water pump up to coiled copper pipe around the intake manifold to keep it heated?

[@sydneychase780]

Yes this works good!

[@johnendresen202]

I believe the '72-'73 Mercury Capri had a water heated intake manifold.

[@deang9061]

Love watching the process, not sick of it at all. I keep checking to see if there's an other installment. To watch the artest at work.

[@deang9061]

Also, in the early 60's Ford used a carb spacer with a water jacket for the FE's. Would that provide enough heat? It's cheap and simple.

[@daledavies2334]

And one of those velocity stacks DV calls useless. DV also talks about the Airgap style manifolds do not transfer heat, so they require annular boosters. I believe you could put annular boosters in all 4 Holley venturis. Edelbrock AVS2 come with annular primary boosters, which give better atomization of the fuel as it enters the air stream.

[@shaggydogg630]

Keep it up UT. I once hot rodded a Ford in-line 6. Lots of fun and surprised a lot of V-8’s.

[@ssnerd583]

i wanna do a MAX'd OUT 300 w/boost.....lots and LOTS of boost!!!!! maybe an old school Paxton 0_o

[@trojan440]

Makes all kinds of sense. Keep the old technology going. Nice job tony.

[@horrible1083]

not sick of it at all, really good investigation and problem solving. thank you keep it coming!

[@rockymeyers4030]

Maybe your stumble could have been fixed by Holley EFI. You could ask Dan at DDs speed shop for help😊

[@jeremyhanna3852]

Actually all the efi bolt on units that look like carbs all say no slant 6 and no Buicknail heads they both have small runners that are hard to tune

[@SpeedyG289]

😂

[@jamescameron6819]

😅

[@jamescameron6819]

@Adam Ballinger like UT is insecure enough to carry a man card. Dude is like a fart in a tornado going where the wind carries hi.

[@sunnyray7819]

U.T. has been there and done that with efi. He probably knows a lot more than D.D. at this point about how everything works. It's a new chapter for D.D.. Is one right or wrong? Or one superior to the other? Depends on what you mean. It's all subjective to personal preference. At the end of the day, If it's what you want, then that's all that matters. But it's hilarious to watch the smack talk. I think some sort of race is in order.

[@UnfinishedProjectDartSport]

Plan Z!!

[@daniellefraser2350]

Troubleshooting like a pro Mr Tony...great show!!!

[@michaelphelps5064]

Being able to read a car is an acquired skill. You are very good at it. Great video showing how they engineered it to be hot, you cooled it down and it doesn't perform as designed any more.

[@JFSmith-nb8hf]

I have a 63 GT that I had the same stumble problem with. Same intake, same headers. I bolted a 3/8 in. alum. plate with two 1/2 in. hose fittings to the bottom of the intake where the exhaust man. went. Ran hoses to T's in the heater hoses to heat the intake. Works like a charm even in very cold weather. If you want to regulate the temp, put a valve in one of the hoses. Keep up the great vids, Unk.👍

[@stevenmitchell5612]

Thank you so much for bringing us along with you with the trouble shooting process. Your explanations of the various concepts are really easy to relate to. 👍

[@timsacco6g694]

That's cool, but what I'm REALLY waiting for is for you to get that Road Runner out of the garage and blow the dust off of it!

[@williammccarthy5696]

83-90 jeep 4.2 6 cylinder engines used an electric heater in the bottom of the intake you could install one and not have to worry about getting the intake hot enough.

[@kennybiggs3944]

Never get tired of something different

[@pittsky]

I've been waiting for this!!!!!!!!!!!

[@josephf593]

Dan HE/HIM, lmfao 🤣 that was a good one tony!

[@jamesandannschmitt6835]

You might want to look at what you can do to get runner lengths more equal. It would probably require fabbed runners and a large/long plenum box. The carb would probably need to utilize analog boosters

[@yodawunn6700]

So, I have a question concerning the carb. On a built 151 Pontiac 4cyl I helped with on a race car, we noticed a huge difference coming off the corners by turning the carb sideways. We put the primary to the outside and the secondary side on the engine side. Once you get this done, maybe turn the carb and see what happens.

[@danfarris135]

The Motorcraft 2 barrel carb on my 66 289 mustang would work fine as long as we raced street drags on the circle track counter clockwise on the 1/4 mile. As soon as we would get to to the final best 2 out of three they make you run clockwise, same problem with the carb starving in the turns when turning right.

[@yodawunn6700]

@@danfarris135 So maybe our issue was a "going in circles" problem rather than even fuel distribution because of unequal distance to the cylinders.

[@danfarris135]

@@yodawunn6700 Just fuel and centrifugal force. You pretty much solved it by rotating the carb. If we were running a 390 holley like the street stocks did it wouldn’t have been an issue. Some times in the old days guys would put baffles in the float bowls.

[@user-cc5nr1cb1r]

I have an Aussiespeed hurricane aluminum intake on my slant. Had a similar issue. I got a 4 barrel hot water carb adapter off of an older Ford v8. Plumbed into heater hose & that fixed all of my hesitation issues.

[@rustywater3219]

Paint the intake black. For thermodynamics reasons, black pulls in heat and releases it better than other colors.

[@jeffreystroman2811]

Flat black radiates internal heat Glossy black absorbs external heat

[@stomper2582]

Black also dissipates heat better than other colors. Causing it to cool off faster. 😮

[@jimr5703]

paint it red. red = FIRE and fire is HOT and hot means chicks and hot chicks are fast. 🤣

[@Nater-zq5yh]

I have a 4bbl on a 300 inline 6 Ford, had the exact same issue with intake heat. For that I used an exhaust manifold off the medium duty trucks, 2.5 inch ported out and still had a heat riser, big went right away.

[@TriStarGearhead]

If that doesn't work, I'm sure you could pull heat off the coolant circuit and you can use a valve to find tune that you probably already thought about it though

[@lgude]

Nicely done Tony😊

[@billhendon1017]

That’s heavy!!! mr Tony ! Would have never thought of that!!

[@donreinholz8121]

How is the 318 build with Andy and David coming?

[@OscarGarcia-sk8px]

Get a thermostat gun and check the temperature of the manifold before making a run.

[@1HeavyHitr]

Of course, it’s obvious! There’s a slant six in there!

[@dextermontgomery3126]

Not sick of it, some of my favorite videos. And I’ve watched from the beginning

[@davidmitchell7183]

I could never get stock carbureted cars to run well, especially in cold weather without having a funcional exhaust crossover and exhaust flapper valve.

[@punch_bowl_turd3005]

would a O2 sensor/ gauge help with any of that?

[@pauberrymon5892]

Try a Thermostat about 2-5°C warmer, it might be a simple fix if low intake temp is the issue.

[@johnkaelberer237]

UT, how about putting the highest heat oil pan warmer you can find on the bottom of the plenum and plugging it in in the pits to pre warm the intake ? Doing this, you are already increasing the temp where you need it without the heat from the engine. Once running, the temp will only go up in a matter of minutes once the heat works it's way through the manifold.

[@JayMalone26]

And the venturi effect is making the intake even cooler, to boot. I wonder if you can use header wrap on the intake to keep the heat in, assuming its being heated from the head alone and not the header.

[@davidreed6070]

Down leg or annular discharge booster. But I understand he's going on the cheap and I respect that.

[@Z_732]

Good stuff UT.. I'd be proud if you stated you saw my comment on that last vid...👍👍that's basically exactly how I would've tried to test it. Very cool man!

[@Carstuff111]

"You guys getting sick of this thing yet?" NO! Plan Z is awesome!

[@LifeSavingDefense]

My first car in 1982 was a slant six and every winter it had to be adjusted and that small tube to bring heat from the exhaust to the intake was mandatory. The heat sink from the exhaust to the intake is the easiest place to start. People underestimate the slant six. I outran people all the time in a Volare coupe.. which says alot… Of course many cars were touched by the fuel emission guru’s in the late 70s but there’s ways around or thru everything especially for an 18 yo kid in a day with libraries if you were lucky and no internet. We are SO spoiled with info today. They may not sound like much to many people but I currently have 4 F bodies in the yard: 1 of 484 Volare 360 Super Coupes, an 80 Florida Marine Patrol car and 2 Road Runners. The last 3 are my sons. I’ll admit many days I wish my first car was a Cuda but these are rarer and more unique and I can’t believe how much people would pay for my extra Volare’ parts just lying on my shelves for 40 yrs…

[@crazylarryjr]

You could do a metal box, that could bolt to the bottom of the intake. You could put a trap door in the front, so that closed it'd trap heat to warm the intake and when floored a hinge could push the door open and allow it to not heat soak

[@richardturk7162]

I had a friend that campained a slant 6 back in the 80s. He started with a Carter AVS carb off a 340 and too much fuel. Tried a 600 cfm AFB and the stumble went away but the mid range was weak. I had several Mopar 6 pak carbs and we used the center carb off a 340 six pak intake and fabricated a new base plate to the Offenhauser 4bbl intake and that 225 woke up and it was like night and day. The car launched harder and pulled harder thru the rest of the run. The car went from 18 sec 1/4 mile ETs to high 12 sec ETs. He ran a 3500 converter and a 3:91 rear gear (8 3/4 housing). He was hell bent on running a 4 bbl carb and the mere mention of a 2 bbl seemed out of the question. After that he understood more gas didn't mean more power. Try some header wrap on the intake runners and below the carb and see if you can retain more heat. A slant 6 is a different animal and squeezing more power from them can be hard. What you would normally think for a V8 doesn't work on a slant 6. Mopar made performance cams that did really well but finding one these days may be hard.

[@budlanctot3060]

Years ago, I bought a Sl/6 4spd 65 dart gt. It had headers, and a 3.55 geared 8-3/4 in it. It came with a 4bbl manifold w/a 750dp Holley. It ran way too rich, so I put a Carter 625 on it. Still too fat. So, I tried a Carter 500 on it. Bingo! That really woke It up. Worked great until the screws fell out of the primary throttle blades. Carter was going out of business around that time, I guess their QC was non-existent.

[@romeubardi4466]

Hey uncle. Here in brasil we have a lot of etanol engines. The key to work an little european engine with alcohol without this stumble is warm up the intake manifold. The way the factories used and works pretty wells was to use the coolant. The manifolds have a water circuit underneath the plenum. It was very noticible when this system clooged up, because the engine would stumble like nothing. Try to aply this, it wouldnt raise the temperature too much, and still dont let the manifold to get cold.

[@illegalmachine]

Use a cheapo IR temp gun and hit the manifold to figure out what temperature it stops breaking up.

[@joeystrains.9316]

Copper tubing with flowing coolant looped several times under the intake manifold tied down with stainless wire.

[@jorgegomez4608]

This is what hot rods are All about I to had watch your video twice it Was packed with so much great Brain twisting theory’s that you Bring to the you tube car videos That no one else does keep It coming

[@lautburns4829]

That’s cool Tony! I had the same problem with a 1972 AMC Hornet 258 six, put a Clifford’s 4bbl manifold on and she stumbled real bad. But when she was warmed up went like hell? Fun times ! Get it back to the track.

[@2000freefuel]

I winder if adding a Cummins 6BT intake heater element would have helped that poor ol 258 get warmed up.

[@lautburns4829]

@@2000freefuel yup, I finally solved the problem and also made a nice exhaust system front to back. Shaved .040 off the head. Went real nice.

[@thomasharvanek2411]

UT Consider a hot water block underneath the manifold, plumbed like a heater core would. Ford 300 style

[@ricjona1069]

Inline 6s are great. Easy to work on, easy to build, easy to maintain. I wish there was a deeper aftermarket.

[@smarternu]

Leave the fuel, add a turbo. Yep, it has been done but not enough. I know it's not what you want to hear, but wow, WE would we LOVE watching that!

[@brotherdio4401]

Check the Flux Capacitor.. try using the blue (cool) one

[@asmoduce]

I know, I know; side drafts bad! boo hiss, no side drafts on Plan Z! I can dig it. Wouldn't three side drafts(on ITB style, short runner manifolds) basically dodge all of these charge temp\fueling\unequal length\plenum based issues though? (and keep 'em coming, I dig the hunt)

[@ssnerd583]

....the sound with 6 ITB's would be sick!!!!

[@ssnerd583]

....the sound with 6 ITB's would be sick!!!!

[@mattgarkus2489]

Yes they would, or a shorter manifold somehow

[@rahowherox1177]

Aye. I'd go the triple Weber s. Works great on the 245 and 265 hemis.

[@scottybodysgarage]

you give me the old stuff that has been forgotten ..keep on teaching us the old

[@dadalebreton184]

Great! I hope it works out. Specialy in the 60 feet range your shooting for. Inline 6's have good torque to trow it out of the hole.

[@user-ly7sl5xg1e]

I have a 250 Cubic inch inline Chevy in a 1971 C 10. After installing a header due to cracked exhaust manifold cold and low speed operation was bad although not a race engine it acted just as this slant 6. Installed heat plate to bottom side of intake manifold and life immediately got better drivability improved drastically. Found out about the heat plate from stove bolt in-line 6 forum. * first ever comment on a you tube video. Good luck and will be watching to see how things go. (Hopefully quicker and faster.) Probably worth the weight penalty.

[@robertwells6454]

Great content Tony. 🤟😎

[@joes3485]

I remember that Chrysler used a different approach for heating the carburetor on some of their K-cars. They had a chamber under the carburetor that had engine coolant passing through it to warm the carburetor. It worked, just had to have a heat exchanger under the carb and some extra hoses etc. You might be able to do the same for the slant-6.

[@gorkzop]

There are people doing that with ford 300s as well! Also really easy to make for our slants

[@gordonwelcher9598]

Thanks for clarifying things with the He/Him. It is so wonderful that nowadays that these things are always taken care of.

[@TMT915]

Could you fill me in , I know about Tim fix it but not Dan

[@rpmunlimited397]

I have routed heater hoses to run under open plenum V8 intakes to make them more drivable in the winter so maybe tie wrap a heater hose around the driver's side of the intake runners front to back to test your theory.

[@b.s.adventures9421]

Not sick of it at all. I dig it. I love the concept.

[@humano1196]

Interesting stuff. Learning alot.

[@bobg3034]

Awesome find Tony!

[@HeadFlowInc]

A lot of 4-6 cylinder guys run the 500 cfm Holley 2 barrel for better response. 225 cid x 6000 rpm/3456= 390.625 cfm at 100% efficiency. I usually add 50 cfm for a well tuned engine exceeding 100% efficiency, so 440 cfm or a 500 cfm would be much closer to optimal.

[@ziggyofthenorth]

Four bangers often use coolant to warm up the intake. You could take an oil cooler, the type that uses coolant and goes between the block and filter. Make a bracket to hold it up against the underside of the intake using the bolts you were pointing out. Then run hoses from the heater connections on the engine to the cooler. Those coolers are usually cheap at swap meets.

[@manicmechanic9117]

A tin heat deflector between the headers and the bottom of the intake might make an interesting experiment . Good luck .

[@kurtpoblenz2741]

Plan Z is awesome!! Can’t wait for the next run 👍🏻

[@cam3002]

Interesting conclusion. hope you found at least part of the solution. Maybe use a heat gun to warm up the intake under the carb just before staging it. I wonder if the manifold design is allowing the mass of the air and fuel to do something odd under hard acceleration?

[@jackwesselman6281]

Us guys in the cold of the arctic have what they call a heat stove. Basically sheet metal wrapped around exhaust that rises up to heat the intake to get the fuel to condense to gas state better.

[@waynebuzzell2483]

Not getting sick of it at all. Love the challenge.

[@donaldhalls2189]

One of the early Holden 6 had a pipe from the extractors to the bottom of the inlet manifold, but I'm sure you'll work it out, thanks for sharing, all the best to you and your loved ones

[@mattycampbell4709]

I believe most, if not all stock cast iron slant 6 intakes also had a heat riser pipe coming off of the exhaust manifold as well. This was mainly for helping out with cold weather starts. Of course these were only 1 or 2 bbl from the factory though, and I've only ever seen the same type of aluminum 4 bbl aftermarket intakes like Tony has here, without the heat riser tube.

[@TheopolisQSmith]

Manifold heating is important on straight sixes. In the late 60’s and early 70’s a friend had a couple of Plymouth Valiants with street rodded slants. One with stock manifold and a later one with headers. He had the same problem with the header version that you have. His past experience with stock manifolds let him figure out his issues right away. And I know on the older Chrysler flathead sixes if you don’t have a functioning manifold heat valve that same thing occurs though to a lessor extent. The only company I know of that offers headers for a flathead Chrysler six also offers a hot water heating system to warm up the carb.

[@rayvreman2002]

Tony, I have a suggestion, instead of screwing around with the exhaust to heat the intake, could you make an aluminium hotbox that is permanently bolts to the intake and is heated from the standard heater points of the engine via heater hose. Then the intake should heat up as quickly as the motor, Also the manifold is a separate piece from the exhaust easier to remove

[@raymondrodgers281]

How about a small heating element where the heat riser was? You could get it to exactly the temp you want. Switch it on a minute before you fire it up, then switch it off once the engine is hot. Cheap and dirty fix that doesn't require any other parts to warm up first. Maybe use one of those old coffee heater things.

[@HamiltonSRink]

Monday morning quarterbacking here: Massaged engine, big carb, tubular exhaust manifold, restrictive economy oriented stock intake manifold. One more hot rodded component yet to be optimized here. I'm thinking that intake manifold is holding you back. Suggestion: How about a wideband air/fuel ratio sensor in the exhaust connected to a graphing scan tool? Might tell you how to get the mixture right where you want it quickly.

[@mattycampbell4709]

I thought this was an aluminum 4bbl intake? I could be wrong as I haven't seen any on the build of the engine. Stock, these usually had a cast iron 1bbl intake on them, so in theory this aluminum 4bbl intake should allow for a more dense intake charge with more air/fuel. It may be too rich in this case, I'd say that even a 600cfm carb would be pushing it, depending on how built the rest of the engine is.

[@HamiltonSRink]

@@mattycampbell4709 If I am correct, and it is the stock intake manifold, then the 4 brl carb is too big. This will result in inadequate flow of air through the carb, which will provide a poor fuel delivery. This car is being built on a budget. A new high performance intake manifold, setup for two two brl carbs, is the way I would go. And not the biggest two brl carbs. Two mid sized carbs. But hey, It isn't my car!