10:1 CR, where to set base timing after install??

[jaymac]

Next weekend, I'm installing my GT-40P's. After being milled .030", they "should" be close to 10:1 CR. Where should I set my base timing for inital start-up?
Does a 10:1 CR Require more timing, or less? Obviously, there will be some negotiation, but is there a better place to start than another?
Thanks,
Jeremy

 

[Michael Yount]

Generally speaking, the more static CR (all else equal), the less timing you can run before getting into detonation. Higher octane fuel will help.

If you want to try and run 87 octane fuel, I'd set it at stock 10 btdc and see what happens. If you're running 93 (highly recommended with your CR) - I'd set it around 14 btdc and drive it. If you hear detonation, back off a couple degrees at a time til you're not detonating.

 

[jaymac]

Right now I run 93 or 91 as I have them time set at ~14*.
I suppose then I can keep the 14* timing when removing the dizzy and re-istall as such!

 

[Michael Yount]

Check/set it with a light....

 

[jaymac]

I certainly will.