The Stovebolt Site Forums The Shop Area Engine Shop 1954 235 engine running terribly

As some of you know i have a 1951 chevy 3100 with a 1954 235 in it with a extreme amount of issues after i had it rebuilt. Currently i have 2 outstanding problems. For starters i have a brand new (rebuild) carburetor (roch model B) and when it is idling fuel almost pours out of the throttle shaft as if its supposed to. my guess is the needle seat is damaged or not seating, or perhaps the fuel pump is making too much pressure. second. i think its relating to the carburetor issue, but when its running it sounds like 2 cylinders arent firing at all. it almost sounds like a rotary engine. i havent ran it for more than a minute so hopefully no damage has resulted. timing is correct, it has brand new champion plugs gapped at .035, correct oil bath air filter is in place with oil in it, havent checked vacuum in a little while, and from my knowledge of smells, its running extremely rich, im not sure rich is the right word. should i start on the carb or check elsewhere? has anyone else had a similar issue? any help is appreciated, i need to know where to start.

I’d try a different carb that was running fine on another engine first.

the original carb i rebuilt myself and it had the exact same issue, it would flood fuel out of the throttle arm. could it be a fuel pump?

What's the fuel pressure? "Test- - - -don't guess!" It should be somewhat less than 5 PSI.
Jerry

If you have a Chinese repop fuel pump it's likely that the fuel pressure is high. One I had would run OK but when I shut it off and let it sit for a few minutes it would flood. Put out 7 PSI.

When you overhauled the carb, did you check the float drop? I found one that had so much drop that the needle would hang up because the float would try to push it sideways. It would flood till you banged on the carb with a wrench. After a while with heavy load it would do it again. Does the float float? Did you check it for leaks by shaking it by your ear to listen for sloshing? Is it plastic? I've seen alcohol permeate them till they sink. Cork too.

As for misfiring on two cylinders, I'd check for gas fouled plugs (Black).

i pulled the plugs and its definately running rich, which could be as a result of the fuel issue, or rather it probably is. all i know is the carb was "professionally" rebuilt. everything was reseated, and so on, like new essentially. when i go to put a fuel filter in the line ill run a pressure test. for now ill tear down the carb and make sure its 100%. i still have the old carb, which would do the identical thing. perhaps then would it be too much fuel pressure? the old carb i rebuilt myself and i made sure everything was 100% spec before putting it on the engine. ill give some more testing and see what i come up with.

this thing is the biggest money pit ever. im pretty positive my fuel pump pressure is way too high. cant get a break with these old works of art can ya?

Did you test the fuel pressure? "Pretty positive" is nearly synonymous with "I have no idea whatsoever", without putting a fuel pressure gauge on it.
Your statement of "100% spec" needs to include testing the pressure.

Update: i found the issue. the people who restored the carb used a metal needle in it. also the flow in port was all gunked up with what looked like a finger nail and hair. i replaced a few parts and presto! no leak whatsoever and it runs 100% better. finally works like it should!

What's wrong with a metal needle valve? GM installed millions of them, as did Carter, Zenith, MOPAR, Ford and a bunch of other manufacturers.
Jerry

nothing was wrong with it but i decided to use a rubber tip to avoid any possible issue. thats all

Good luck with that decision.

The rubber tipped ones don't work with fingernails and hair either.
Sounds like you got it figured out.

As London as its Viton and not.Butyl rubber

As long as it is viton is what I meant