Timing advance

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Timing advance

Post  diehardfordtruck on October 20th 2014, 10:15 pm

I'm building a 429,.030 over pretty much stock bottom end with bolt upgrades. Heads are C8VE with a mild port job with 2.19 & 1.76 SS valves,Comp cam 562/565 weiand intake with a 750 DP carb..C6 auto with 2400 stall 3.90 rears,all in a 4400 lb 63 F100..I discovered my HEI distributor vacuum advance doesn't work...Question,do i need it,while I'm at it do i need to upgrade the weights and springs,is the adjustable advance to limit timing advance? I guess what I'm asking is for a lesson in old school timing and tuning...any Help would be greatly appreciated.
Thanks,Charles

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Re: Timing advance

Post  FalconEh on October 20th 2014, 11:40 pm

Duraspark?
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Re: Timing advance

Post  diehardfordtruck on October 21st 2014, 6:39 am

HEI...Looks like GM....

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Re: Timing advance

Post  diehardfordtruck on October 21st 2014, 9:12 pm

Someone has got to have something to add...I thought I was asking a legitimate question....

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Re: Timing advance

Post  cool40 on October 21st 2014, 9:29 pm

I would think you need the vac advance but the mechanical advance may have already been curved so you dont. Question is how much is it advancing now?
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Re: Timing advance

Post  kim on October 21st 2014, 11:05 pm

In original design the vacuum advance was used as a ported vacuum switch, where closed throttle blades induced high manifold vacuum and made cold starts easier. Ford also used vacuum advance with a thermal switch off manifold vacuum and would advance vacuum with high engine temps to accelerate high load combustion process and bring cylinder temps down.

Most racers use it in reverse as a start retard, hooking manifold vacuum up to direct manifold vacuum. So when cranking initial timing is retarded to that as what would happen with a start retard.. Once engine fires then the manifold vacuum kicks in and pulls the engine up to a decent base advance, with mechanical advance coming on with centrifical force and the tuning of the distributer to establish total advance, all in RPM, etc...


As for needing it, depends how you want to use it, and what your willing to sacrafice. I run no advance mechanisms at all, and actually employ multiple timing retards depending on whats happening. My distributor is set with a 34 degree advance from the get go... with a high speed retard, and multiple stages of N20 retard from various controllers.

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Re: Timing advance

Post  diehardfordtruck on October 22nd 2014, 7:15 pm

Thanks just trying to learn some new tricks,in the circle track cars we never ran any type advance...thanks for the help..

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