The Stovebolt Site Forums The Shop Area Engine Shop ignition timing

Hey all,

I know there has been lots of discussion on this but everyone's application is different so here I am.

I have a 1963 GMC with a 327 with a slightly souped up cam (not sure what, as it was like that when I bought it)
I am running a edlebrock 600 and my tranny is the sm420

I have vacuum advance and a vacuum gauge to test with but I can't seem to get it right. I have used my timing light and put it at tdc ( I assume the middle line is tdc) but it still will not run at optimum.

There are no vacuum leaks. I am just not sure how to adjust the dist., then the fuel screws on carb and then the idle screw or in which order for that matter.

Any advice from you oldtimers (not necessarily in age) would be awesome.

Signed up and coming oldtimer to be:)

Thanks
Shane Hamilton
Warrensburg, mo

Make sure you disconnect the vacuum advance hose before you check the timing.

The original timing specification on the 327 would have been 4 to 8 degrees before top dead center, but that was before the cam swap. cammed-up small blocks like lots of initial timing, probably 12 to 15 degrees before TDC. The problem is when the centrifugal advance comes in, and total timing gets too high. With the vacuum advance disconnected and the engine running 2,500-3,000 RPM, the total advance needs to be 36 or 37 degrees BTDC, no more! You will probably need to find someone with a delay-flash timing light to set the timing that way, as the normal harmonic balancer doesn't have marks that far around it. Set the delay number to 36, rev the engine up, and adjust the distributor housing until the timing mark is on zero. If the timing at idle still doesn't suit you, you'll need to find someone with a distributor tester and the knowldedge of how to alter the centrifugal advance limits.
Jerry

Thank you so much! I will do that.

Shane