View single post by Jensen Healey
 Posted: 03-08-2015 04:46 pm
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Jensen Healey

Joined: 03-11-2005
Location: San Anselmo, California USA
Posts: 983
The vacuum capsule was a 4-6-4R giving 4 degrees of retard at 4 to 6 inches mercury.

The vacuum capsule does not change the timing under load, but during off throttle deceleration when the mixture is lean. I believe the retard capsule was used to limit certain pollutants at idle.

I did find a 4-6-4 capsule listed for Lotus with 45D4 up to 1980. It would be prudent to contact the experts:

There's an article on vacuum advance here:

Cheers, Kurt