Re: Timing

Good Monday! (if there is such a thing...)

So I was tuning up the 383 (1966, Weiand Intake, Holley 750, cam, headers) on the weekend, and decided to check the timing. With the vacuum advance disconnected, my base timing was well past the timing tab, considerably, sitting at about 20+. Something's not right. When I put it at 8-10, the revs came waay down and it ran like crap. Doing the timing with a vacuum guage, it seemed to run best where it was, way advanced.

I did some measurements and marked on the balancer where 35 would roughly be (going to order a timing tape), as I don't have a timing light with the advance dial, so I could check my total advance. I put the revs up to 3500 and set the timing at 35. It was very close to this already. I took the car for a drive, and it ran the same as before, as I ended up not really adjusting the timing much from where it was originally.

The car runs ok, no signs of detonation, but seems a little sluggish, which prompted me to check the plugs, timing, etc.

From what I have been reading, it appears that a stock distributor's mechanical advance should throw about 27 degrees of advance in when the weights swing out. This on top of 8 base timing would give the generally accepted norm of around 35 degrees total mechanical advance.

I also noticed that I have no vacuum advance at idle. The distributor vaccum canister is plugged into the vaccum port on the front left of the holley 750, and, at idle (1000rpms), with my vaccuum gauge connected, it's pulling nothing. Soon as I pull the revs up a bit, I get vaccuum. Going to reroute the line to take vacuum directly from the manifold, as I have vaccum at idle there.

So I'm trying to figure out why my base timing is so high. These are the scenario's I've come up with...

1) Previous owner set the timing with an advance timing gun and set total at 35, maybe the weights aren't swinging out enough or stops modified to minimize mechanical advance, but why?

2) Due to the cam, maybe was setup this way to accomodate for the lack of vacuum advance at idle (maybe answers 1 above)?

3) Balancer has slipped, but that wouldn't explain the low amount of advance between base and total.

Any ideas?

Thanks

Jay