Timing advance question
 

Im compiling all of my car info and I came across my ignition advance numbers for my 327/340 in my 63. (it doesnt have the Duntov cam, some other solid lifter cam)

It runs pretty good as is BTW.

According to my notes, I have 11* initial timing
Mechanical adds another 14* all in my 3200 (IIRC)
Vacuum can B26 provides 16* with 12" vacuum at 700 RPM.

Would I be better of to have more intial, and less vacuum can?
What would anideal combo be? I note that the B28 canis recommended, but its 16* advance also.

Will I gain anything If I epoxy or weld the Advance can to limit advance to 11*, and advance the initial to 16*?

This is the same dizzy that I will be using on my 383, so Id like to plan ahead to dial it in correctly.

Thanks!

I would think your centrifugal would.add a lot more than that to get you near the magical 36* "all in" number.

I would suggest 12-14 initial with the B-28 vacuum advance control providing 15+- connected to full manifold vacuum advance like it originally was.

The original 1963 distributor has a 24* centrifugal advance and you should try to get it all in by 3000RPM.

This set up provides,

1, 27-29* idle advance, (12-14* initial + 15 vacuum)

2, 36-38* WOT advance, (12-14* initial + 24 centrifugal)

3, 51-53* total cruise timing, (12-14* initial + 24* centrifugal + 15 vacuum)

Ok, so perhaps I was mistaken beliveing that 41-42 was the absolute max with vac.
You are saying 52* cruise is ok? I have the Lars paper here somewhere...

Ill have to look inside the dizzy and see why Im only getting 14* advance.

I doubt its the original distributor as well.....Id be surpised anyway..

48* at cruise is quite safe; 52* is "on the edge". My '61 handles 52* at cruise quite nicely but you have to be careful -- you don't want detonation or "trailer hitching"...

How much manifold vacuum is present on your engine at curb idle RPM fully warmed up?

What carburetor are you using? If it's a tach drive Corvette distributor you can set the centrifugal advance curve without to much trouble.

I have 12" vacuum at idle. Gm dist. Maybe original. AFB carb. 340hp car

If you have 12" vacuum you need the B-28 that's pulled full at approx 8" vacuum, that will keep the idle stable.

The original Carter AFB is part #3461. If you have this carburetor take good care of it because they are hard to find. Start there and target your timing like I posted above.

My carb is a 3721 SB 64 250hp manual... I believe.

The 3721 will work just fine. If you have the original aluminum intake manifold consider wiring the heat riser open use a thick gasket between the carb and intake.