1961 Cadillac Hesitation Blues

[Otto Skorzeny]

Hi Jack,

On a 50 year old car, the factory specs are a good place to start but they aren't always applicable today. Gasoline isn't the same as it was 50 years ago nor is the engine. Even a rebuilt engine is going to differ - even if only slightly - from the specs laid down by the factory when it was new.

All of this combines to make it necessary to alter the tune up specs on the engine.

[D.Yaros]

FROM:  http://www.thecarburetorshop.com/

For carburetors manufactured AFTER ABOUT 1935, and a vehicle that is mainly driven at altitudes of sea level to 4000 feet, we suggest the following calibration changes to use ethanol fuel:

   E-10 -lower float levels 1/32 from original specifications, increase main metering circuits fuel flow by 5 percent.
   E-15 - lower float levels 1/32 from specification, increase idle jet flow by 5 percent, increase main metering circuits flow by 10 percent.
   E-85 - nope, not going there at all, good luck to any that try it!

Additionally:  Accelerator pumps with neopreme skirts should be changed to those having leather skirts.  Foam floats should be changed to brass.  Carburetors with vacuum metering systems may need a recalibrated vacuum spring.

Failure to make these changes will cause the engine to run lean.  A lean running engine will run hotter than normal, and this can cause premature failure of valves, warpage or cracking of cylinder heads, exhaust manifolds, etc.