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Have done a bunch of searches and have only come across "initial" timing values ranging from 10 to 15 with plug removed for late models. Older non-EFI 460s talk about "total" timing in the mid 30's.
Is this the same value for later EFI models? Is "total" checked with plug out or left in to see what controller and mechanical reach?
I have a rebuilt stock piston'd late 70's (low compression) block with rebuilt stock late model EFI heads/intake.
Runs fine at 12 degrees initial but curiosity got the better of me. I grabbed the light and started twisting hoping to reach a ping and back off a little. Then see what that value was. Could never reach a ping. Could get it to stumble at nearly 30 degrees.
When weather warms a little, I'll go verify timing pointer alignment.
I had the vac gauge hooked up but couldn't make much of a determination as my build has always kind of hunted for idle rpm. About 100 rpm swing. Gave up chasing that years ago. My idle RPM is between 850-950.
The EFI distributors do not have any mechanical advance weights or movable parts. The rotor is driven directly by the shaft. ALL dynamic advance is handled by the computer.
Thank you. Hadn't looked for mechanical. Just assumed it did. Will put base back at 12, put plug back in, rev it up with light to see where controller peaks. Am assuming mid 30's.
One of the weird things about the total timing requirement of most engines is that it isn't really determined by how much timing it can take without causing detonation. On a dyno what I've normally found is that you get to a point where adding more advance hurts torque and horsepower. From what I've seen most of these engines with factory heads do the best with about 34-36 degrees total. I can't say that I've ever seen one wanting more than that at wide open throttle accelerating at 300rpm/sec. One version of the EFI head is a high swirl design so its requirement is probably less.
Thank you Dave. I'll play a little in a few days and probably end up where I started. I've put 9K miles since assembly with timing at 12 (assuming pointer accuracy). Had just gotten curious if it could be dialed in a little better. My curiosity usually gets unbroke stuff broke.
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