Stock Timing for Big Block

[Dr. Evil]

Maybe someone can help?
In the original service manuals it calls for 396/402 timing to be 4*BUDC.
That is 2 incrementals above the 0 Mark.
Why is it everyone is cranking them up to 8 and 10 and 12?
Does it really help?
Is it this crap corn a hol gas or are you guys and gals just making the stock engines max out performance?confused:2:

[CE20934]

The stock spec is an emissions thing. Less advance at idle increases hydrocarbons which allows the AIR system to be more effective. If you don't have an air pump, you can bump up the timing to 8-12°. Some folks run up to 16° base timing, but it depends on the cam.

I'm running 12° BTDC on my 427 because: 1). the cam manufacturer recommended running 4° advanced of the stock spec, and 2). the butt dyno & ear oscilloscope say the engine runs better with base timing between 12-14°. I also run with the vacuum advance hooked up to manifold vacuum which smoothes the idle even further.

I'm running 12° base timing, 14° vacuum advance (all in @ 10" Hg), and 24° mechanical (all in @ 3000 RPM).

FWIW, the hardline maximums I have heard for BBCs are 36-40° advance at WOT (base + mechanical) and 48-52° at cruise (base + vacuum + mechanical).

[Rollie396]

I also started out with factory specs and was really disappointed with the performance.After some homework I bumped it up to 10 and it's a totally different engine!I haven't had time to fine tune it,but it's soooo much better now.