| Timing Questions [message #360353] |
Sun, 29 November 2020 08:35  |
uprooted
Messages: 72
Registered: December 2019
Location: Hilliard, OH
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Happy Sunday. Up to now I've been primarily running the GMC with the timing set by vacuum and/or driveability. I finally put a timing light to it and it runs best at 25 degrees base timing (1100 RPM)! We have 3.70 gears so I checked total mechanical advance at 2,900 RPM in park with vacuum advance disconnected Im getting about 36-37 degrees advance. So dist weights are adding 12-13 degrees. I pull full vacuum (hook vac hose to manifold) and get 55 degrees BTDC. So vac can is adding around 20 degrees max. I've verified the timing mark on the balancer matches up w piston #1 at TDC. There appears to not be any notable slop in the timing chain. I've not been able to detect any pinging under load. Edit: I tried the method Jim Bounds posted on YouTube a couple weeks ago for tuning and Oldsmobile, and surprisingly, I eneded up at exactly 8 deg BTDC! I thought "cool, that really worked!" But the thing ran like crap and backfired out the carb when I pulled the throttle. Something else is going on here
Edit/clarification: This is a point distributor with pertronix module. Advance weights taken off and cleaned, lubed.
Corey P /
Hilliard, OH /
1974 Glacier 26' /
3.70 FD /
ION Wheels
[Updated on: Sun, 29 November 2020 09:00] Report message to a moderator |
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