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Old 07-09-2012, 09:26 AM
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DanEC DanEC is offline
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Location: Little Rock area, AR
Cobra Make, Engine: ERA Street Roadster #782 with 459 cu in FE KC engine, toploader, 3.31
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Quote:
Originally Posted by jwd View Post
Okay, I was reading it as 36-38 initial plus centrifugal advance. Now it makes sense. I know what causes the surging. When I tune a car and encounter it, I change the vacuum can to one that had a little less total advance. Usually only a reduction of a few degrees is needed.

Jim
Oh - yeah, I can see now how it could be read that way. I understand.

My BB Chev runs low vacuum due to the big, old-school cam and I had to purchase a special vacuum canister that starts to pull in at 6 inches vacuum. There might be one out there like it with less total vacuum advance but it was easier to make a little bracket that mounted over the arm and had a tab that stops the rod from advancing the entire way. That way I reduced the advance that was kicking in while cruising on the road and stopped the surging. Cruising down the road that surging/missing can be really annoying even if you understand what is going on.
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