Thread: Got Time? (Part 1)

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Originally posted by White Sands
Ok, this seems like the place to answer my question. I unplugged my vaccum advance and set my total timing to 38 at 3000 rpm. This caused initial timing to be 16 degrees. I plugged the vacuum advance back in, on the driver's side port on a Edelbrock 750, and the timing went up to 39 degrees. I have a Mallory Unilite and I believe the vacuum can is adjustable. Does this mean I have 23 degrees of vacuum advance? What should I adjust it to? To check my curve, noting the timing every 500 rpm, should I do it with the vacuum hooked up? This is for a 383 stroker. Wish I knew all the exact specs but I don't. The vacuum at idle is 15.

Referencing the 39 degrees total, it sounds like you're shooting the timing at idle.

Just out of curiosity, how big of a cam are you running and what is your idle speed?

The total timing - assuming it's at idle - of 39 degrees shouldn't be a problem.
The idle fuel/air mixture is lean and it takes a while to burn.

I have very close to the same timing in my 462" Buick engine.
8 degrees initial and 32 degrees all-in on the mechanical.
Most of the Buick speed houses - as well as my own experience - indicate that 32 degrees total is about right.

Depending on the situation (cams, C/R etc.), Buicks will run very well with as little as 28 degrees total all-in.
(All timing figures BTDC.)
Timing at the 550 rpm idle speed with mild cam and manifold vacuum supplied to the vac can the total timing is about 36 degrees.
(When I ran a bigger cam and dual quads the idle speed was right at 600 rpm.)

Looking from here, 38 degrees seems a touch high for a street SBC even if it's a fairly big one.
I believe most Chevy guys like 34-36 degrees total.

Is the engine difficult to get rolling on the starter with 16 degrees initial?