Timing - Advance Curve & Vacuum Advance - Pontiac GTO Forum
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post #1 of 3 (permalink) Old 05-27-2019, 07:10 PM Thread Starter
 
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Timing - Advance Curve & Vacuum Advance

Two good video's you can watch that has great info and hands-on explanations.

How To Re-Curve A Distributor, And Why! 24 minute video

How Vacuum Advances Work 12 minute video
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post #2 of 3 (permalink) Old 05-29-2019, 06:28 PM
 
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Good videoís thanks PJ, .......a lot done by feel, he is a pro, but I have found that when you use two very light springs it often brings the centrifugal advance in on top of the base timing at idle.

#so trying to get all in at 2500 and above idle timing is often not easy. Some cars can take all in at 2500, I have curved Corvettes that way, they like it, but others will ping on acceleration as too much timing is in early.

I think you get better street performance by sticking with Lars formula. And using 10 degrees vac advance from manifold vacumn, that easily gives you great timing on acceleration, without having the Centrifigal so low....

Real light springs can cause that detonation. He likes adjustable vac cans, they can work but I prefer the can limited to 10 Degrees positively by a stop, like Lars sells or a can limited to 10 degrees.

Driving a street performance car without vac advance will be giving up quite a bit, cooling, strong running .....early and at cruise.

But whatever you do check the numbers on your car with a timing light.....And donít set your springs first nail down that centrifugal first so you know what your base and total will be. Springs I do last,...28 to 3800 RPM will be a strong runner, usually with no pinging or covering over the idle with centrifigal timing.
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post #3 of 3 (permalink) Old 05-29-2019, 09:12 PM Thread Starter
 
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Thought you might like it. I am on board with timing adjustments being more individual. I think 2,500 all-in on the timing is too much and even 36 degrees total is a bit much - neither of which are absolutes for our Pontiac engines. He is more of a Chevy/Ford builder and uses these engines/parts in his demonstration videos. He explains things pretty well and uses examples that you can "see."
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