Re: 1951 288 Vacuum Advance Source

Posted by JWL On 2022/9/1 13:29:34
I believe one reason for having the distributor vacuum chamber connected to full manifold vacuum is to reduce engine heat at idle. At idle the distributor is at full vacuum advance. It is retarded ignition timing that can cause more engine heat. Setting the engine timing with full vacuum to the distributor does involve a couple of extra steps over the ported version.

Remember, the distributor vacuum chamber is just a way to modulate the timing along with the mechanical advance.

Some Ford products only used a vacuum control for the timing and some other manufacturers - early on - used only mechanical control for the timing. Engines used for racing tend to use only distributors with only mechanical control as engine vacuum is low due to valve operation of the competition ground camshafts.

Others here probably have much more knowledge on this subject.

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