[swp1983]

Ive been reading alot on the pros of vacuum advance but my hotrod runs better without it! ( maby im doing something wrong) 1963 nova 327, HEI, big unk cam, 3000 stall, 10:1 comp, 373's, holley 650, single plane intake. With vacuum advance it dies in gear and in park idles around 1300. Seems to run much better without it ( better idle in/out of gear). However I have noticed hotter temps and more fuel use without it. So how can i get this thing dialed with vacuum advance? Initial timing is @ 13 and all in by 3200. Do i need to recurve or get an adjustable can? Ive also searched for vacuum leaks, none. Also tried ported and manifold. Whats next?

 

[cobalt327]

Ive been reading alot on the pros of vacuum advance but my hotrod runs better without it! ( maby im doing something wrong) 1963 nova 327, HEI, big unk cam, 3000 stall, 10:1 comp, 373's, holley 650, single plane intake. With vacuum advance it dies in gear and in park idles around 1300. Seems to run much better without it ( better idle in/out of gear). However I have noticed hotter temps and more fuel use without it. So how can i get this thing dialed with vacuum advance? Initial timing is @ 13 and all in by 3200. Do i need to recurve or get an adjustable can? Ive also searched for vacuum leaks, none. Also tried ported and manifold. Whats next?

An adjustable can will help in some if not most cases. You probably need to use ported vacuum, not manifold. Tailor the curve around using ported vacuum for the vacuum advance by using a lot of initial timing, total mechanical timing all in as early as the engine and combo will allow, limit the vacuum advance to about 10 degrees, and you can have the best of both worlds.

More here, also see the rest of the Ignition advance section of that page.