All of you have helped with my carb and timing issues. I think I'm on the down hill slide finally. Here is my questions about timing and jets.

My car right now is running pretty awsome with a base of 20 or so and a mechanical of 38. The total timing with vacuum advance is 55-57 since it bounces a bit. No pinging crisp response just really running well. I wonder is that to much???? I have thought about bringing it back to 50 total.
My carb hasn't torched any plugs for about a month so maybe that issue has been resolved. The timing seems to have helped that issue on top of closing the secondaries up they had to much transfer slot showing.

Now in fast idle my headers glow so I think a slight jet increase is needed. With a pv what should the difference between the primaries and secondary jets be 4 sizes? Right now I have 72's in front and 74's in the rear. I think it needs a bit more like 74's front 78's rear.

Without a rear PV, I run the secondaries about 8-10 sizes larger. 2 is not enough. Base and total timing sounds OK if you're not getting any detonation, although I'd cut the vacuum advance down to 45-48º.

I'm running an MSD Pro-Billet distributor (PN# 85551) with no vacuum advance and the 18 deg bushing installed.

Intial timing is set at 22 deg and total is 40. No problems with mine. graemlins/thumbsup.gif

Thanks I suspected the secondaries were off. I plan on tuning the vacuum advance down so my total is 45-48. It is running great right now I must say.

Should I up the primaries a size or two to help with the fast idle header glow. It only glows at the base by the heads and stops once I kick it down to idle.

Well, it doesnt really matter what mine is doing relative to yours, does it.

The only issue I see is the 50-55 total w/ vacuum. I'd limit that a bit. If this is a performance motor, you'll start hammering your rod bearings pretty good with those numbers.

Pat's right on. I;d go a bit richer back there.

Fast idle, just sitting there, is like breaking in a new mtor. Headers will almost always glow some. No indication of A/F ratio can be made from that observation.

How would it affect the rod bearings? I'm not arguing the statement just mechanic in training. smile.gif

Detonation hammers on the top of the pistons. The rods transfer this hammering to the rod bearings.

and detonation happens with too much advance

i had a 406 sb and it liked alot of timing too, i always ran it around 55 total, i also made the carb real rich, like it would idle on a 30 degree morning cold start with no choke, right away. it was a 780 holley (3310) with 77 and 79
jets and i cant remember if it had power valves, i will lean towards it didn't.
john