The Stovebolt Site Forums The Shop Area Engine Shop Triple carb manifold

Hi all, I have a 62 c30 with a original 235, and recently came across a 261 out a 56 Canadian Pontiac both with 848 heads.
I'm looking to put a three carb manifold on whichever of these engines I decide to use.
The problem I'm having is that when searching the web there seems to be intakes that although are for these engines they seem to be for different model years, re pre 59 and post 59 the same appears to be for dual exh headers.
Would this be a attachment issue , or clearance and linkage issue??
This would be just for looks as I plan to use the 261 carb in the center and although i'll have carbs on either end they will be blanked out between the carbs and the manifold.
What problems might I look forward to setting up the carbs this way

Thanks JOHN

John,

1. Make sure the "848" head has the six additional coolant passages used on the 261 (2 additional passages between pairs of cylinders).

2. Any 1954-63 235 or 261 intake or exhaust downdraft manifold/header should be "bolt-on" compatible.

3. Assuming that Canadian & USA versions are same/similar.

Post links to the parts and people will be able to give more reliable answers.

Not sure about the 62, but earlier body style trucks have clearance problems with the steering column and shift linkage when a 3-carb manifold installation is attempted. The fake carbs on the ends is definitely the way to go, even on a 261- - - -not enough air volume to make use of that much carburetion anywhere except wide open throttle/high RPM!
Jerry

Thanks, ( I"m assuming ) Guys

I'LL SPEND THE WINTER LOCATING THESE PARTS AND HOPE TO HAVE THEM INSTALLED BY MID MAY. I'LL LET YOU KNOW HOW IT TURNS OUT
AS FOR POSTING LINKS, I DON'T EVEN KNOW WHAT THAT MEANS LET ALONE DO IT, I'LL WAITE TILL I GET HOME IN MARCH AND HAVE MY 5YEAR OLD GRANDSON HELP ME.

JOHN

No need to yell- - - -we're old, but not quite deaf yet!
Jerry

What problems might I look forward to setting up the carbs this way

Don't expect your port-to-port mixture distribution to be as good as original.

"This would be just for looks as I plan to use the 261 carb in the center and although i'll have carbs on either end they will be blanked out between the carbs and the manifold.
What problems might I look forward to setting up the carbs this way"
Why would the intake port to intake port mixture distribution be adversely affected?
- The two side carbs are blocked-off at the base of those carbs.
- The center carb feeds all three intake ports to the head (as is the case with the original intake).

The key to improving cylinder fill average is to use three smaller carbs, and solid linkage, rather than progressive (or with the ends blocked off).

Anyone ever see a 3.8 Jaguar with progressive linkage, or with fake end carbs? Its been awhile, but I seem to remember they ran pretty well.

The 3.8 is about 232 CID, the later 4.2 about 256 CID.

As to the clearance issues, I don't know.

Jon.

"What problems might I look forward to setting up the carbs this way"

one carb working (center)
two carbs blocked off (sides)

Of course, you are correct, Jon.

However, would the single "working" carb, as described, on a 3-carb manifold (as described) cause any problems?

Apparently, the issue is not performance.

The question seems to: will there be any negatives in performance, compared to a single carb manifold?

The only think I can think of is the triple intake has sharper corners out on the ends then a single intake does. It might not have the smooth air flow as the stock intake, but it should run and function OK. As long as it has heat under it, it should work just fine.

The air/fuel charge to the outer-most cylinders on a triple manifold with the end carbs not functioning will see increased turbulance from the "dummy" plenums, versus the stock intake.

Thus the end cylinders will run leaner.

This will certainly be measurable on a dyno. How much? Don't know. If you wish, try it. The loss will be greater at higher RPM's.

Personally, I would just do my homework, and run 3 carbs, but then I just like multiple carbs.

Jon.

Speak for yourself. I don't hear as good as I used to and I can read the all caps easier.
Carl

so after much deliberation, I have chosen this method to resolve my cylinder to cylinder mixture distribution problems.


https://picasaweb.google.com/lh/photo/58I8MDtyPHJ7i8RhiV3vG1qOAF7zdfhu9NXFqRDgeM8?feat=directlinkhttps://picasaweb.google.com/lh/photo/58I8MDtyPHJ7i8RhiV3vG1qOAF7zdfhu9NXFqRDgeM8?feat=directlink

Did you find that at the end of the rainbow under the pot of gold next to the bushel basket full of hen's teeth?

not quite, but it took 30 years, and about 10 times what I paid for the truck to find it. Now all I need is to convert it to electronic injection, and the #6 stack hits the firewall...There are numerous problems, but it's definitely not a 350.

Is it for a GMC?

Hex2hockey sticks of a score there.
To bad about your first born...
All the 235 guys have long block envy and all us long block guys are drooling right along with them.
Will you make it do this? and let us watch?

I'm going to put it on a 216, as the truck is a 53, and 53 was the last year for the 216. I still have to get the injection figured out. But until I pay off the house, I will be short on excess cash. (18 more months, yippee!!!) Then there was the new/old mallory magneto that was on ebay for a long, long time, and it finally went for $350 or so. I was pretty upset I missed that one, it sure would have fit in nicely with this theme, Oh well. I have actually been looking for a T-bucket chassis, that would solve the firewall interference issue. But I am really out of room in the garage. No, really, there is no more room.... The GMC heads are still being made, and not horribly expensive, well maybe they are kinda expensive. But not like this. I am going to be rather gentle to it, I would really, really dislike breaking it.

Ok, I give up. What is it and why are we so excited about it? Am I supposed to be drooling right now??

Best video I've seen in 2016. Awesome.
I got no eye deer what y'all are talking about : long, short blocks , hockey, all caps, first born, and triple carbs...

But that video is awesome.
Brad

it is a wayne 12 port head, with hilborn injectors, there were only 125 heads made, and even fewer injectors, with the last of them being made in 1954 or so. They were full on bonneville stuff, they fielded a 235 in the indy 500, in I believe 1954. They are extremely hard to come by. The reference to my first born is, that is about what they cost, if you are to ever find one. And since I am fond of things that aren't small block chevy in these trucks, and everyone and his brother has the fenton dual set up. I just thought this would be something different. As far as drooling that would be up to you.

Speaking of things "not small block"- - - -a SCCA racing team I worked with briefly back in college had an interesting pickup that toured with the race cars. It was a 50-something Chevy 3100 with a Ferrari V-12 shoehorned into it. It had some sort of 5 speed trans, and a Jag XK-120 rear end.
Jerry

I like it brokenhead- hope you keep a post/build thread going.

OP, does this answer your question?
LOL!

Brad

Helluva miss with my double hockey sticks shot huh? My bad.

My long/short block crack was due to my being ignorant they actually made some for the 2" shorter 235 blocks I thought they were all for the GMC blocks.
But that motor In the vid IS a sweet sounding machine...

I would love to make a tech tip or whatever you would want to call it, but I don't know how to do all the pictures and stuff. Peggy sent me some instructions, but that is assuming even rudimentary knowledge of things like "open your browser", and "create a file", I do not have a clue. I don't even know what a browser would look like if I were to run across one. I apparently missed that day in the school of life. Odd thing though, I know how to program a PLC...

So, are you going to try to squeeze it in a truck with firewall mods? Or use it in something else? (Saw you mention a t bucket)

naw, it's going in the truck. I just need to get curved stacks, really shiny curved stacks, with 6 little air filters...

Cool.

What are your plans for the exhaust side of the engine? The blue flames (literally) in the YouTube video are cool but I assume some sort of header would be preferred in an actual vehicle.

6 little air filters

You're kidding, right?

I have the original down turn cast iron headers as well, It came with rocker arms, an intake that can be fitted with up to 5 standard carbs, valve cover, everything but valves, springs, and a side cover. And no I am not kidding about the air filters, why would I run something that cost this much without them?

They may be small enough to choke the stacks. Each suction pulse is an entire cylinder drawn very quickly through a small tube, without that huge buffer of the manifold plenum. I'm guessing: the stacks and throttle discs are about 1-3/4"? Because the pairs are so close together you may find that making a base to accept 2 stacks with a single filter works better, 3" wide and 6" long, as tall as possible.

For all of you salivating over the head, it fits a 216 (or 1941-52 235) just fine, but it's 15 bolt - won't fit the 18 bolt 1953-* 235/261.

like I said there are numerous issues. As in lots, many, a bunch. This will take a while.... but it should prove to be fun.

Ok. I am sufficiently impressed. Congratulations on the score. You definitely need to keep us posted when you get it running.

Thanks all, the response was greater than I expected.
The reason for staying with the single carb is that I understand that multiple carbs (functioning) could ad horsepower at higher r.p.m. but at the cost of some low end torque. I'm not sure what percentage of these gains or losses equate to but I'd rather not shed any low end grunt as I try to keep the r.p.m.s between 2000 and 3000 and I need all the grunt i can get.

John

P.S. I hope this is not to loud.

Multiple carbs feeding the same (plenum) manifold will have worse low speed response.
3 individual carburetors using separate manifolds have excellent low speed manners, they're just a lot of money and trouble.