Re: Excessive fuel consumption

Posted by Tim Cole On 2016/8/8 6:17:05

Poor low speed performance with good high speed performance is symptomatic of retarded valve timing. Although the car is low mileage there may have been work done on it during the past 67 years.

A vacuum gauge will indicate this problem, and a compression test should be done as well. A dwell meter can be used to check the distributor condition. It should remain fairly stable with increasing rpm. If it increases more than two degrees the distributor needs to be repaired.

If the motor is running rich the plugs will be black as will be the case with poor ignition.

The Custom 8 should get around 15 mpg with good carburetion, but those carburetors are old which reduces that figure. Low compression is a big culprit for poor fuel mileage.