Thread: advance question

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This maybe be a stupid question, but i dont know so ill ask anyway. On a chevy 350 with a vaccuum advance Should the car sound the same at idle and when reeved with the advance hooked up as it does with it disconnected?

Yes and no.
Provided you have the distributor vacuum selected to manifold vacuum and not ported vacuum.

Disconnect - and plug - the vacuum line and the engine will idle slower.

Under load, when accelerating, the vacuum advance backs off and the mechanical advance is setting the timing where required by engine rpm. That means no change in sound there.

Keep in mind that mechanical advance is rpm controlled and vacuum advance is load controlled.

It's possible there could be a difficult to discern change in sound between vac line disconnected or not when cruising at light throttle with the engine lightly loaded, but I doubt the human ear could really pick it up.

Unless you're hearing air hissing from an open vacuum line.

Look for a post titled, "Got Time."
It has quite a bit of information in it about timing et al.

What should the vacuum advance be hooked to? Ported or manifold? Is it bad to leave the vacuum advance disconected?

chevy reccomends ported, i reccomend manifold.... advance will actually increase performance and gas mileage.... so i reccomend leaving it connected