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Carburetters on 1931 12 cyl

Started by David Instance, February 05, 2006, 01:18:37 PM

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David Instance

In October 2005 the Automobile (UK classic car publication) did an article on a 1931 12cyl roadster - it showed the engine with Cadillac/Johnson updraught caburetters.

My 1931 12cyl coupe has Tillotson Toledo (YR2) downdraught -

Anyone know if they were an option at the time - or when the change took place?

Paul Ayres #5640

David - Tillotson carburetors were never standard on your Cadillac.  Someone has removed the original johnson carbs and installed substitutes.  This was not uncommon on these cars, but is absolutely not correct.  Paul

David Instance

Thanks Paul, youre a mine of info! Despite being not correct would the Tillotsons have improved performance? Any other reason they would have been changed? Could I find any original to replace?

Paul Ayres

David - The original carbs were a bit crude, and sometimes were replaced for carbs with better fuel control, hence the carbs on your car.  Performance may have been better.  Occasionally, carbs and intake manifolds show up on ebay, or at swap meets like Hershey.  You will need both carbs and intakes to change back, since your intakes will most likely have been modified to mount the carbs on top.  The correct installation will also need a pair of V-12 air silencers and correct carb and choke linkage.  Paul

Ken Andersen # 21420

Paul,  I take it that the same goes for the 28 Cadillac 341-A also. Is there any way of modifying the original carbs to ensure better fuel conrol?

Wayne Womble

I dont have much problem with the carbs as far as running goes. They are actually very sophisticated for their time. They have much more flexability than most other vehicles of the era. with  The biggest problem I see, is keeping them from flooding and leaking when shut off. I am still working on that one. I get them working good most of the time and then once in a while, they dump on you.

Paul Ayres #5640

Ken - Yes, these carbs are essentially the same.  There is no modification that I know of.  I just run as lean as possible by keeping the float level low, and being sure that the air valve is adjusted properly;  that is, just touching the seal at room temperature.  I also recommend blocking off the heat passage from the exhaust manifolds to reduce the heat in the area, and removing the exhaust heat damper in the left exhaust manifold to avoid it being stuck in the closed position.  Paul