quote:Originally posted by Rocky:
So Doug -
Are you saying the advance plate mechanism that is connected to the vacuum canister in the Ford Distributor vibrates, or something, and affects the BASIC timing of the system at high RPM?
I can see that a person could remove the linkage to the canister easily, but isn't the pickup mounted to that plate?
How would one then fix the plate in place?
Thanks -
Rocky
What happens is that first off, you are not getting any vacuum advance at WOT which essentially over 6,000 rpm operation is.
Centrifical force is pressing the plate to move and the diaphram in the vacuum canister tries to resist but the flexibility of the rubber diaphram in it isn't strong enough to hold the plate steady, so yes, it begins to essentially cavatate/vibrate.
Exactly at what rpm this happens I can't tell you.
I have run vacuum advance distributors up to about 6,800 rpm with seemingly no problems. That's probably because I am not using it under "race conditions", that being on and off the throttle.
For serious racing, you must pin the "advance plate" if the distributor is equipped with one
You just bolt the plates together using a piece of tubing as a spacer between the plates. Something like a #8-32 screw with a lock nut and a 1/8-3/16" long piece of tubing. A plastic "stand off" would work also as a spacer.