Model A stutters on right-hand turns

[Matt Harwood]

My father called me today to help him with his 1930 Model A roadster. It starts and idles well, and drives just fine in first and second gear, but when you turn right, it stutters and backfires. In third, it also seems to stutter. I thought that perhaps the fuel level was low (there was about 1/4 tank) and it was sloshing off the pickup, but as an experiment, I shut off the gas valve and it runs fine for about 30 seconds, unless you make a right turn. So my next guess is a float issue. Before I tear into the carburetor, which seems to be some variation of a Zenith, but not a totally correct Model A unit (photo attached), is this something that's common to Model As that someone might be able to advise?

Thanks!

[MCHinson]

I believe that is a Tillotson Model X carburetor. Rebuild kits are commonly available for it. I have successfully used those carburetors in the past but there are several reasons why I would suggest swapping it for a correct Zenith carburetor. I can't remember exactly what causes that, but it is most likely a carburetor issue that a rebuild or replacement will resolve. It is also possible that there is an ignition issue that only happens with right turns. I have heard of those sorts of things in the past too. Just the right flex happens to open or short something. Those sorts of problems will drive you crazy finding them.

[Luv2Wrench]

Different time period, but my 1994 Dodge Ram pickup would stall on hard right turns. It turned out that an ignition wire that had come loose and on hard right turns would ground itself on the exhaust manifold!!

[Guest shadetree77]

I had a similar problem on my '52 Buick. It was a combination of too much fuel pressure and a float level problem. The float wasn't closing the needle valve completely and the build up of excess fuel pressure was forcing the valve open causing a flood of fuel. I never did figure out why it only happened on turns. Something to do with centrifugal forces maybe? Maybe the float leaned more to one side during turns. Who knows? After I corrected the float level and decreased the fuel pressure the problem went away. Good luck to you!

[Pete O]

We had a fella in our club where the car would stall out on turns. But then it would start back up and run fine, until the next turn. The problem turned out to be that one of the wires in the horn had come loose, and whenever he turned it would short out against the horn body. Another fella had intermittant loss of power and backfiring. That was due to those new fangled wireless bottom distributer plates. The brass contact on the plate had lost it's "springiness", and it wasn't making continuous contact with the pickup leg on the points. I'd say that if your stuttering and backfiring problem is a new issue, I'd look for an electrical problem first before digging into the carb.

[Beltfed]

Not a for Ford expert by any means. Suggestion: Could you hook a voltmeter to the primary wire in such a way to be able to read it and take a short test drive (I would use an analog VOM which would be easier to see). As you take a turn you could see if the voltage drops, this might give you a clue as to what's going on (as suggested above). Good luck.

[rons49]

Not a for Ford expert by any means. Suggestion: Could you hook a voltmeter to the primary wire in such a way to be able to read it and take a short test drive (I would use an analog VOM which would be easier to see). As you take a turn you could see if the voltage drops, this might give you a clue as to what's going on (as suggested above). Good luck.

Matt. That indeed is a Tillitson X. Good carbs except for one glaring issue. They tend to warp due to the white metal that they are made from. Heat causes the issue. An air leak can be oh so small and on a turn the base may flex and as the fuel moves to the inside of the float chamber( right turn) air is drawn in. I too, advise a good Zenith. Could be a gasket leak in the carb or intake manifold. Ron

[Matt Harwood]

Just to follow-up on this, we've ordered a new Zenith as recommended. We're also going to pull the manifolds and replace the exhaust manifold gasket, which is leaking. Will report back and let you know if it has solved the problem (I sure hope it does!).

Thanks for the advice!