When I bought my Pantera, it had a bit of a backfire if you were accelerating in the lower RPM range). The PO thought it needed some carb work.
When I got it here, a buddy of mine (markVI/ 4280) helped me with some carb adjustment, a carb rebuild (really, there was nothing wrong with the carb) and Timing adjustment. This was the problem - the timing was too retarded. We reset it, and my car ran great.
I took the car on a run up Mount Lemmon (26 mi. climb from ~3000' to 8000'). The car ran great all the way up, and ALMOST all the way back. About 1/4 mi from my house, it started to backfire again.
I got it into the garage, and re-checked the timing, and lo & behold - RETARDED! Cranking it a little more, it backfired worse, then wouldn't start any more!
So with Wade's assistance I pulled the distributor, and we confirmed that the pin was disintegrating.
But in my case, it appears the problen was due to an incorrect setting of the gear position - too high. I had zero wear on the bottom of the gear (which I understands runs on a thrust surface). So the cam gear pulls down on the gear, but since it was not positioned correctly, all the downward force from the drive gear was transfered to the pin.
We measured the gear position, drilled a new hole in the gear and shaft, and upgraded the roll pin. I am back on the road, and my timing no longer keeps slipping.
Thanks, Wade.
- Rocky
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