Total timing on a BBC

August 13, 2026, 04:47 PM

Alaskaracer

quote:
Originally posted by sr4440:
What A/f ratio are you running?

The reason I ask is I have had maybe a dozen people come in with a known good methanol combination, we run it, get dyno numbers, find out they are running a rich A/F ratio. Then pull a bunch of timing, start leaning the engine out until it stops making HP, then add timing back in until it stops making HP. Always end up with less timing and more HP. Usually add a little more fuel just for the engine to not be as weather sensitive.
But your engine may be different, I don't believe I have done a 9* head engine.

Here's something fun Google "At stoichiometric air/fuel ratio which fuel burns faster gas or methanol."

My afr's are 5.0-5.2 at the hit, leaning to about 5.6ish on the top end. Car kept picking up and it's happy spot was at 38*. I've ran it at 32, 34, and 36, and all were slower. The afr's I run are also it's happy spot. If I lean it, it will slow. If I richen it, it will slow. So it's pretty well tuned where it's at. My chambers are softened, 7* cut.