V12 Caddillac running on 6

[Arlen]

The 1931 V12 we just bought has been getting a tube up. It is running but has no power. We still have carbs to go through but today we noticed that air was only coming out of one exhaust pipe and only one sides exhaust manifold was getting warm when running. It starts easy and has good spark at the plugs. We also see that it has good fuel flow to the carb. We are thinking that the carb on one side must be clogged up. Any other ideas? Arlen Evans

[Chris Cummings]

Arlen,
As you know these engines will run smoothly (if anemically) with one cylinder bank firing.  You are likely correct about a fuel obstruction within the carburetor. If the needle valve is stuck, the float hinge jammed, or the float swollen to the point that it cannot move freely, that cylinder bank would not be getting fuel.  It is also possible to get debris in the passage drilled through the carburetor casting that leads from the inlet fitting to the needle valve seat.  The screens in the vacuum tank are the only fuel filter the car came with.

What is your car's body style?

Best regards,

Chris Cummings

[gary griffin]

 There should be air coming out of both pipes. Just cranking it will bring in air and send it through the pipes.  Is this the model with two cams, one for each side?  If so you may have a different problem. If the valves on one side are not opening there will be no air flow.

[Chris Cummings]

Could be wrong, but I think he meant that one tailpipe was putting out regular exhaust, but the other was just pumping air. That's what happens when only one side of one of these engines is running.

The '31 through '37 V-12 engines have a single cam, so if the plugs are sparking, and the other side is running, the problem would most likely be the carburetor on the non-working side of the engine.   

Hope that helps.

Chris Cummings

[gary griffin]

 I think you are correct Chris, and I was thinking of the two completely different V-16 engines. I do not know if both variations occur in the V-12.

I was just taking his statement literally and making a comment I guess.

[Steve Passmore]

Don't want to state the obvious Arlen but did you check for a spark on the bank of cylinder that aren't working?  That twin point setup can give problems with only one bank firing. I had this problem with mine and Ty Stinson went through the same problem with his V12 and was even using his car for a while just running on 6, amazing.

[Arlen]

I've got good spark everywhere. Ill be taking the carb apart this weekend to see what I can find. If the carb seems ok after cleaning and I don't see any difference what else can I check? The reason I say only 6 are firing is one sides manifold gets much hotter than the other. After several minutes of running, the passenger side manifold can still be touched by a bare hand.