The Stovebolt Site Forums The Shop Area Engine Shop 216 Intake / Exhaust Manifolds on a 235, help?

I have a 1954 3604 with the original 235 engine that has had the intake and exhaust manifold swapped to the 216 manifolds. I read in another post that a 216 carb on a 235 would run too rich ( fuel mixture ). A 216 carb will not install on a 235 intake manifold so the discussion must mean that someone else has a similar situation. Can someone clarify the "rich" mixture issue and advise if there are any solutions other than getting the correct intake/exhaust manifolds and correct Rochester B ( yeah I know, get a Carter YF2100 ) . This issue is aggravating since I have a very nice functioning intake /exhaust manifold and carb....but the exhaust pipe is sooty black so I'm thinking its running rich. Ok, open the floodgates of knowledge and experience and give it to me straight!

Recently, carbking recommended the Carter WA-1 as an option for stovebolts. They were original equipment on Olds and Pontiac straight 6s and 8s. I believe one of the Olds applications was 236 cubic inches.

They are small base (same as your 216 manifold), plentiful, and cheap on the big auction site.

What carb are you running now?

Tailpipe residue is not an accurate depiction of carburetor health anymore.

Go stick your finger in the tailpipe of your new car. There will always be a black residue. It's the nature of modern gasoline.

I'm interested to what extent the idle mixture screw can help with the soot. Seems to be worse after replacing the Rochester B with a Carter on my 216, as evidenced by the black spot on the garage floor. All parts stock for the 216 in my case but since it's closely related to Dusty's question will tag along here. To be honest I've never even touched the Carter's mixture screw, so probably should do that. Runs great with it otherwise though.

My truck leaves the same mark, and I’ve done all kinds of tinkering with the idle screw. I’ve decided it’s just a thing upon initial startup, and likely not a big deal. Others can chime in if they see it differently.

It's the nature of partially burned hydrocarbons, or leaving the choke on 100 years ago

Once the engine RPM gets above 1000 or so, the idle circuit completely ceases to function, so you can tinker with the idle mixture screw until you wear out the threads and it won't make any difference at all on a sooty tailpipe. The proper way to adjust idle mixture is to turn the needle clockwise until the intake manifold vacuum starts to drop (too lean), back it out slowly to get good vacuum, and go about 1/8 turn richer (CCW) to avoid a stumble on acceleration. Then use the idle speed screw on the throttle shaft to set your desired idle speed.

THEN LEAVE THE COTTON-PICKIN' ADJUSTMENTS ALONE! They're for adjusting idle- - - -nothing else!

The high speed system consists of the main jet, the venturi, the float level, and the power valve, and on virtually all carburetors, the only "adjustment" that can be done is changing parts. A VERY few carbs have adjustable main jets, and none of them say "Rochester" anywhere on the casting- - - -most say "Zenith" which is a contraction of "EXPENSIVE". To run a 216 carbuteror on a 235, someone would have to file slots in the throttle body mounting holes (I gave one like that away last week), or install a 216 intaqke/exhaust manifold on a 235. Either way, the increased airflow through the carburetor will cause the venturi and main jet to run the mixture too rich at any speed above idle. That's why the new "one size fits none" copies of old carbs made in third world sweatshops by teenaged slave laborers don't work.
Jerry

Going to paraphrase something I’ve seen from Pre-68 Dave here a number of times: A 235 will run pretty well with 216-sized manifolds and carb. Perhaps a bit more throttle response (makes sense), giving up a little bit at higher RPM.

I also know at least a few here that have direct experience with the same. “DADS50” ran a 235 with a 216-sized YF. Struggling to come up with another name, but he’s not the only one. I think there might be also be a member or two using the Zenith that is sized for the GMC 228.

Random, semi-related musings:

* I now believe the “hype” about the YF. The improvement in my engine’s smoothness and performance was very real when I made the switch.

* I have a theory I’d like to test someday, if I ever win the lotto and get to piddle with trucks full time. Stovebolts of all shapes and sizes suffer from poor fuel distribution/ efficiency due to pretty awful intake and combustion chamber design. It is aptly described as a tractor engine, and there ain’t much we can do about that.

However, I wonder if some improvement in performance or efficiency could be made by INTENTIONALLY using the 216 manifolds on a 235, along with a carb that is properly sized for the displacement. (I.E. the Olds application WA-1 I mentioned previously) Perhaps improve atomization with the smaller ports and increased velocity. Still have the right about if fuel and air at a given RPM.

It’s entirely possible that approach would produce a negative result. But I’d still love to try it just to find out.

Hello folks! For reasons I cannot explain, I'm unable to use the "quote" function to respond to you folks individually.............so

Jerry - I hear ya. If I could find a decent , working, 235 exhaust manifold ( not wanting to have to remove, bush, replace heat riser plate/shaft...) I'd install the correct intake ( yes I have one ) and exhaust and that newly rebuilt Redline Rochester B carb I have setting on the shelf. If I was smart ( and I'm not, and I'm also cheap ) I'd go find a Carter Carb and be done with it.

JW51 - I currently have a Rochester B that has the 1.500" throttle plate. (for a 216 I suppose ) , hey, you live in Missouri ! I live in Missouri. Hmm. Sounds like you read several "musings" . Good info, thanks.

Panic - true, tailpipe on my SUV , 1.6 Turbo, lots of black sooty stuff. Hmm...

Skooter - stand by for more action, inaction, who knows....

Otto Skorzeny - maybe I don't have a problem?

The Carter YF that fits a 232 cubic inch AMC engine has slotted throttle base holes that will fit either a 216 or 235 manifold bolt pattern. I've got a couple of them stashed away. With a little bit of tinkering with the main jets and power enrichment system, it can be used on just about any displacement engine from 230 to 300 cubic inches or so. Did I mention that it's also a Carter? Plenty of 'em on Ebay at reasonable prices!
Jerry

Dusty -

I am also cheap and also not smart. Must be a Missouri thing. Both of the small flange Carter carbs I mention (the WA-1, and the 216 flavors of the YF), are notably more affordable than a 2100s in similar condition. I lucked into a deal on my 2100s several years ago. Otherwise, I’d still be shopping.

1) Find a Carter and sell the rebuilt Rochester to a resident of a state who is no more smart than are we, but less cheap.

2) If you’re happy with the way it currently runs, just run it.

3) I bet we can scrounge you up a working 235 exhaust manifold from somewhere. I don’t have one. But they’re around.

You don't.

I should take pictures of the black spots behind all of my cars. They're all tuened properly and run like Swiss watches. The Packard, AD Chevy, and Mustang all have black spots on the floor that deposits on startup.

The Cadillac has black deposits in the bumper exhaust ports.

The Ford trucks blast soot onto the garage door.

Once they're all warmed up the exhaust is clean and the engines run just fine.

The 216 and 194" Gen-3 use the Rochester "B" with 1-1/2" throttle disc and SAE #2 (small) flange pattern.
194: 1-1/16" venturi
216: 1-7/32" venturi

I also found a larger #2 flange carburetor: 1-9/16" throttle disc, used on some Pontiacs (OHC L6?): 1-5/16" venturi

I'm going to call The Carburetor Shop on Monday.

Early oil slinger 235s came with the same intake and manifold as the 216s. I imagine that the carburetors had the same bolt flange spacing as what came on a 216 as well. I don't know if the carburetors were the same on the inside (jets, etc.)

Carl, I remember asking about the dipper 235 carbs, but I don’t recall the answer I received. My foggy recollection is that they were the same as 216 carbs.

Dusty53 Listen to jw 51 it'll fix your problem,but the economy may suffer some.

bouymaker, I understand your advice. Just so you know, I've spoken with Jon before and he was most helpful. My call will be to address pricing on two carburetors he has listed. I'm working on the options that have been proposed. Thank you for your input.

fixite7 - that's the direction I'm heading. Hey, at least at the end of this adventure I'll have learned something new. Economy ? Oh heck, it's not a daily driver so ....

I just bought a BRAND NEW Rochester BC carburetor for 20 bucks plus shipping! It's never been on an engine. Unfortunately, it's got some holes drilled in the castings. The throttle body, air horn, and main body have each got a 1/4" hole drilled in them- - - -Rochester sold, or possibly gave away a bunch of carbs to automotive schools for training purposes, and drilled holes in some strategic locations to keep them from being used on vehicles. With a little creative tinkering, I believe I can plug the holes and end up with a "new old stock" carburetor. The brass tag (yes, it's actually there!) identifies the carb as being for a Pontiac flathead 6 cylinder engine from the late 1940's to mid-50's, 230 cubic inches, IIRC.
Jerry

That 1950 decision to make the Rochester B an OEM carb on Chevys was not popular with Carter. They vowed to sell a million replacement carbs for the Rochester, and marketed them very aggressively. When the one millionth Chevy YF came off the assembly line a few years later, the CEO of Carter had it gold plated and presented it to the CEO of GM!
Jerry

Thanks to everyone for the advice and input, much appreciated.

Dusty 53 I may be wrong on economy,carb king might help you get good economy and clean tailpipe.

fixite7 - I sent you a PM.

FWIW, many years ago I had a Studebaker Champion w/170 cu in L-head six. It came to me with a Carter YF, which developed a stumble off idle, perhaps associated with unleaded regular that was just introduced. While I worked on that carb, I installed a Zenith from a 228 GMC to keep driving it to work, etc. The stude ran OK but got terrible gas mileage by comparison with before. The Zenith had the adjustable main jet and leaning it out didn't help the gas mileage. I fixed the Carter reinstalled it and all was well and I was back to high 20s MPG on the road. During this saga, gas hit $0.50/gal so I was motivated to get it set to rights.

1Ton tommy , sticking with the factory setup or the correct Carter after-market replacement seems to be the best approach. I'll update the post next week after I've made a few phone calls.