427435

My engine is being set up for a dyno check run this week. As wiring the TI distributor and module to work might be a problem without a wiring harness (staying on the car), the engine builder is going to just use a Chevy HEI distributor. I know that the initial timing is supposed to be 4 degrees BTC, but what should the max centrifugal advance be?

DansYellow66

Usually total timing (initial and centrifugal but not vacuum) is targeted for around 36 degrees on generally stock engines. Some engines might tolerate a bit more and some may prefer a degree or two less. IMO it's not going to be very responsive for street driving if your distributor curve will only allow 4 degrees initial timing. I have mine set up for 12 degrees initial timing and 24 degrees centrifugal but it's also not stock. Unless they are going to dig into the distributor the safest thing is to power time it to 36 degrees total and let the initial timing fall where ever it falls for now.

Powershift

Keep the BB at 36 degrees with hi-octane gas. Ideally you would want it "all in" by around 3000 RPM.

Don't think you will need vacuum advance for a dyno/break-in run. Normally the RPMs are above 2000 RPM and often the carb is at WOT.

Larry

427435

Thanks. It looks like total timing at wot should be 34-36 degrees.

DansYellow66

That should be pretty safe and close to optimum if you are still running high compression pistons.