Misfire at cruise, popping/afterfire at 3000RPM

Righty Tighty said

This was a while back, but it was when I was trying to measure the curve. I started at 14 advanced, idle speed was around 850 IIRC, then revved until it stopped advancing, which was at 2800 RPM, and the advance was then at 24. New distributor from Summit. We had talked about changing springs to see if I could get more total advance, but the transmission took the front seat for a bit.

Edit: I was typing this response while you posted. I forgot I had a separate thread where we talked about that.


The bolt patterns are the same, so I think it would be possible.

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That distributor can be adjusted for the amount of advance it allows (by loosening the two screws and adjusting the window width), and how quickly (with springs).
But, if the billet dist behaves/misfires the 'same' as the factory distributor, I'd go back to the factory one again and check the idle/all-in timing and get it close to what Mattax has suggested. Focus on getting the max timing correct and let the rest land where it does - it's far less important than figuring out the misfire, and misfire isn't going to be affected by what the idle timing happens to be.

No reason for a stock distributor to not work, and it would work with the limiter plate you bought (if it becomes necessary).

I think the outer carbs are your likely culprit for the breakup, but your ignition is so out of sorts there's no way to confirm that until the timing is correct.