This may be a dumb question but how do you determine what the timing of an engine should be after you have done a rebuild and changed a few things like a different cam.

Start with 12* initial and check to see that you get about 20* mechanical giving you 32* total 3000 rpm. If it runs good there then boost it up to 15* initial and see if it is still OK, no detonation or hard start when warm. If it is still good then you should be all set.

Thank you, much appreciated

SSCAM,

Your motor needs at least 36* total, probably more like 38* total. Bring it to ~3000rpm's (or when the advance stops advancing) and set total to 38*, and let the initial fall wherever it may. A motor w/any kind of cam will want 16-20* initial, so hopefully it will be in that range. If not, you may need to have some work done on the distributor. If you get a stumble or back-fire when you floor it, chances are it wants more initial.

Some other notes - make sure all the advance is in before 3000rpm, and make sure your vac advance is disconnected when doing any of this. BTW, your engine will want manifold vac advance if you have anykind of cam.

I agree with most said already, but 20* initial timing is too much IMHO. You could have starting issues with that much base advance. I do agree that you should have about 36* total advance, all in by about 3000 rpm, using about 12* initial with about 24* total mechanical advance.

Then, when you plug in "manifold" vacuum, the idle timing will jump and you should have a decent idle.

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