The Stovebolt Site Forums The Shop Area Engine Shop Engine requires near full choke to run

The engine requires near full choke to run at idle. when running at higher rpm the choke can be opened a little, as soon as the throttle is reduced the engine starts to die. any suggestions would be appreciated. Thanks

should have mentioned this is a 54 chevy 3100.

Did this just start to happen out of the blue?

Was it running good before?

Did you do anything to it, tune up?

Engine/carb set up?

Points/hei?



?

You've got a clogged idle passageway somewhere. Try this before you dig into the carburetor- - - -Rev the engine up close to cruise RPM and slap your hand over the top of the carburetor. Hold the throttle wide open as the engine bogs down. Take your hand off, and let the flood clear out and rev the engine again. Repeat several times. Choking the carb down at high RPM floods all the passageways with liquid gasoline from the float bowl, and it might flush out the clog. If that doesn't help, dismantle the carb, soak it in a dip cleaner, flush with HOT water and use lots of high pressure air to blow all the passages clear. Reassemble with the correct rebuilding kit, making sure all the parts of the kit match up with what you removed.
Jerry

“Clap your hand over the carburetor “, almost spit my tea out. I can just see a couple of folks standing there clapping frantically over a fast running Stovebolt. Regathered my self and read on. Good simple cure (clamping your hand over the carburetor) and if it works it’s cheap too. 😁

Yep what Hotrod Lincoln said. Not to mention its fun. And if it dont work, take a min and think about what exactly you just did, then do it again..

Martin,

That deserves a round of applause......

"The sound of one hand clapping"- - - - -be sure to get a recording of that!
Jerry

Sorry a little late getting back to answering the posts. The engine was stripped down to the block. Nothing internal. Repainted. installed new plugs, distributor, new wires new vacuum advance set timing.

Started with the beebe on the timimg finger. Once started moved distributor until it was running smooth (choke still mostly closed).
Checked for vacuum leaks , found none.
took carb loose and added gasket between the insulator block and the carb. do not have gasket under insulator block.
when i put the carb back on i noticed a leak around carb. Must fix this befor i do much more.
Before i found the leak i sprayed some carb cleaner around intake manifold and found a leak.(what is the torque on manifold bolts?)

Plan to torque manifold, determine the carb leak.

Will then try the clapping on the carb.

Thanks and i do appreciate all the suggestions.
frank

There should be no gasket between the insulator and the carb. Putting a gasket there blocks the vacuum port.

I have always used a gasket between the insulator and the carb.
37-54 gasket
54-62 gasket

I have never had to use a gasket between the insulator and the manifold. But, using one (to stop/avoid a leak) would probably cause no problem?

The insulators often have slots in them - to match the slots in the gaskets.

37-54
54-62

The gasket supplied in the universal carb kit did not fit - it blocked the vacuum port. Footnote said not to use gasket with 1954 truck with insulator. This has been discussed in this forum previously.

I'm joining the conversation late. The Model "B" in my humble opinion is one of the best ever built for the purpose it is used ON.Everything everyone has advised you is good advice. The "B" can be a little touchy and usually lets you know when it's not happy with it's lowly position in carburetordom but, if you look at its history it has been used in everything from airplanes to boats and everything in between (forgive the soapbox boasting). A good way to check for leaks is to wave acetylene gas around every vacuum spot on motor.If the engine rev's up there is your leak. In a pinch you can use map gas in a propane torch. Now lets me ask you has the "B" been rebuilt by you or anyone? If so let me know and we will start from there. DOC.

Well, folks- - - -we've got a unicorn- - - - -somebody who LIKES a Rochester B!
LOL!
Jerry

Thanks.
The gasket i purchased has a cutout for the vacuum port.

thanks Doc Hall. I like to keep the old cars as original as possible. i do change over to 12 v mainly because it is easier to get a part on the road. i like to drive them. as an example. Have driven my Model A from Kansas to new Hampshire and to Victoria BC.

I tore the carb apart to day and put it in a dip to clean it up. There was all kind of crap in the carb. am going to leave it in the tank at least 24 hour and the see how it cleans up. i have a kit to rebuild. any suggestions on the rebuild process.

All the dip cleaner does is soften the deposits- - - -it doesn't remove them. Once you're through soaking, rinse the parts repeatedly in HOT water (almost boiling) and use lots of high pressure air from a needle-tip blow gun to clean out all the drilled passages. One instructor I had at the General Motors training center in Memphis used to say "Put 55 gallons of air through every hole in the castings!" The air is what does the cleaning, not the dip solution.
Jerry

Two and a half years ago I spent a lot of time, did a lot of work and made an objective study of the Rochester B and its problems...including a way the everyman can straighten the castings using cheap and commonly available materials/tools. You can see some of that here: https://tinyurl.com/v3oeses

Many other things were considered, discussed, etc. I'd suggest reading as much of what was posted back in late summer of 2018.

Is this a 216 or a 235?

I haven't used carb dip for probably 40 years. But leaving a zinc alloy body in overnight often would damage the castings beyond use! I hate to see even a Rochester B treated in this fashion. 30 minutes was sufficient. The new dip is probably not as stout.

Agree with Jerry 100 percent about the softening of deposits but not removing them.

When I was still doing carbs, I used an ultrasonic cleaner; with a very exotic cleaning agent.......................................Dawn dishwater soap.

Ultrasonic cleaners are much cheaper than when I bought mine ($5200. for a quality USA-made unit large enough to dunk a Holley 4150 complete), but even at current prices, the average enthusiast may not be able to justify the cost.

A "poor man's" cleaner can be made from an empty 3-pound metal Folger's coffee can. Simply mix up a good solution of Dawn and water, place with the carb parts in the can, and BOIL. The heat and the soap loosen the deposits, and the roiling action of the boil flakes the deposits off, and the grease will be absorbed by the Dawn.

Jon.

I've got several vibrator cleaners that I use for polishing brass for reloading. I converted one of them to use a liquid container filled with Trisodium Phosphate (concrete cleaner) and water. A couple of hours in the vibrator, followed by a hot water rinse and lots of air gets a carb squeaky clean.
Jerry

Found the problem. After finding the intake leak, took the manifold off. all four exhaust ports leaking bad. Took the manifold and had it surfaced. re install and the truck purrs like it is suppose to. Thanks for all the suggestions. it kept me looking for the problem
frank

When when one is removing manifolds from each other, it is best to snug up the 4 bolts holding the manifolds together, then tighten the manifold to head bolts before tightening the 4 manifold bolts.

Ed