1930 model a carb problem

T

towmater49

Junior Member
i recently purchased new carb for model a.installed it and it idles fine,when accelerating the carb shoots gas out the back of carb.when adjusting idle screw it doesnt change idle at all.when turning fuel mixture choke rod it doesnt help either.some knowledge would be greatly appreciated.help,sos
 
Wow you have listed a bunch here so let's try to narrow this down.

Is this a Zenith or Tillotson or Marvel Carb?

1st you bought a new or rebuilt carb from a person or a business? First thing I would do is contact who I purchased it from and ask what is going on.
2nd. Shooting gas out the back of the carb do you mean gas is shooting out towards the back of the car? It's important because technically that is the front air intake of the carb. The fuel bowl is the back of the carb.
3rd. When the idle adjustment screw won't make any difference in how the carb runs it generally means an intake leak or their are other problems with the idle circuit.
4th. The Gav valve is for extra fuel at cold start up and will either richen up the gas and air mix or lean it out.

I would spend a few minutes at modelabasics.com and check out his excellent article on carbs.
 
yes,gas is shooting out air intake,found that head gasket is leaking in a couple places.could that be enough to hender the gas into intake properly? maybe crud stuck underneath valve and is not seating properly, gonna pull head next. zenith carb. thanks tincup
 
It sounds like you have compression going where it shouldn't.Dirty valve,bent valve,broken valve spring,burned valve,or valve adjusted too tight.Head gasket could be blowing into the cylinder next to it.No carb will work right until the real problem is corrected.Number one thing to do is check the compression.Not so much the psi in numbers,but the difference between the cylinders.
 
You have a leaking intake valve. Maybe a leaking intake manifold gasket, or wrong timing.
First thing is check your compression on each cylinder.
 
Posted this experience before. The jets can inadvertently be installed in the wrong position in the carburetor body. It will run, but obviously will not function properly. Once installed correctly, stalling stopped, idle adjustment functioned, and GAV function was restored.
 
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