C5AF distributor question

[Wbulk]

That's a good point and exactly why timing is based on individual engines and how it was built. It sounds like in this case you have a high duration cam with reduced manifold vacuum at idle. Vacuum is also increased by raising the idle other than adding more timing. The double edge sword is with engines with radical cams when you raise the idle to far you expose the idle transfer slots in the throttle bores and you loose adjustability in the air fuel circuit. This whole issue is why some after maket ignition systems have a built in retard on start. It makes it easier to start and have adjustability.

I think I would still go with the 10L for 20 deg. of mechanical. With it not working before, this engine is going to be a lot different and I think you will see the power and mileage improve.

Wayne

[patrickt]

I agree with Wayne. Go with the 20 degree limit, and start off with 15 degrees initial timing, so you have a total of 35, and see how she runs. Then tweak it up a bit from there to see what she likes. Double check that your TDC really is at TDC (using your piston stop). If there's any doubt at all about your timing marks then just ignore them and mark one line at 36 degrees BTDC (that will be exactly one tenth of the circumference of your balancer from your TDC point). Then just set it at that line at, say, 3000 RPM, run it; set it a little before the line, run it; set it a little after the line, run it; then put it where it runs the best. The actual number doesn't matter, you'll just learn that your best timing is maybe a hair past the line at 3000 RPM.