Engine: 1950 Champion Dies on Idle

[Jersey2J]

The '54 3R is running great thanks to forum members.

Now I have a new issue. My '50 Champion inline 6 will start, rev, and drive fine - as long as I keep the accelerator 1/8 depressed. Whenever I let off the gas to a normal idle, the car dies. I can restart it without issue, but as you can imagine, not being able to let off the accelerator is a big problem.

I have enough gas, enough battery, the oil bath air filter is tight, and the carb was rebuilt not too long ago. The car has two fuel pumps - NOS and electrical as back-up - so I know that fuel is getting to the engine.

I adjusted the idle (one screw), but it didn't solve the issue. Any ideas?

Thank you in advance.

[rstrasser]

Need to know about what speed is the engine running at with 1/8 throttle. Normal idle speed should be between 500 and 600 RPM.
Idle speed is best set with a tach and a vacuum gauge. Once the engine timing is set it is a matter of adjusting both the idle speed screw and the idle mixture screw for the correct idle speed and the highest vacuum.
If it is not possible to have the engine idle at the normal speed I would look for a vacuum leak or? Hard to tell not being able to see or hear the engine.
Ron

[Warren Webb]

Does it idle normally when cold? If so, that would indicate a vacuum leak. Go over what Ron suggested & make sure all gasket surfaces on the intake assembly are tight, rubber vacuum lines aren't broken that would cause a leak. Since you mention that you have adjusted the "one screw" for idle, is that the mixture screw on the base of the carb or the idle screw on the carb linkage at the bottom of the carb? You may possibly have the mixture screw set too lean.

[tbirdtbird]

worn throttle shaft can give vac. leak....
and there are 2 'idle' screws...one to crack the throttle and one for the idle mixture

[RadioRoy]

Do you know how to find vacuum leaks with a spray can of B-12 Chemtool?

Basically, you do whatever you can to get the engine to idle as slowly as possible with your hands off, even if it means sticking shims between the idle screw and the choke cam.

Go around the carb body and the manifold and the windshield wiper motor and hose, spraying B-12. If the engine changes speed, either faster or slower, you have a vacuum leak at that point. If the car has a lot of time on it, the throttle shaft can leak as tbirdtbird says, but every place there is a gasket, or a transition in materials, is a great potential for a leak.

When you find one, mark its position and keep going until you find all of them.

You can even have had a soft slug fall out of the carb body. There is at least one 50 Commander starlight out there with a nail head epoxied into a hole in the side of the carb.

[bosshoss61]

Good one---maybe a stuck carb float, maybe the flow thru electric pump is not a flo-through. I think I would remove the fuel line from the carb and hit the electric pump. Check the flow.
RB

[bosshoss61]

Could you let us know what you find---I too have a 50 Champ with the 169.5 flat top.

[Flathead Fred]

I also had that problem with my 50 starlite I took off the carb and blew out the idle circuit -problem solved ,no problem since

[Jersey2J]

Again, many thanks for the help above.

I can now get an idle after adjusting the throttle and idle screws, but the mix is now too rich. I had to lock down the idle screw and open up the throttle because I must have an issue with the needle or the float; the fuel continues to come out of the venturi even when the idle screw is locked down. The car runs a bit rough, but at least I can drive to the mechanic if I can't troubleshoot the float myself.

Regards,
Jason

[bosshoss61]

Jason, there is not a whole lot to those carbs if it is the original one. And I'm sure there are a lot of good mechanics on this site. I probably have the exact same carb on a manifold in the garage that came off my 1950 Champ/ 170cu.in.. and I'll bet you could find a kit to rebuild yours on page 185 of the Studebaker Int. catalog.

Good luck
Rick

[RadioRoy]

So... did you figure it out yet? What was the solution?