Intermittent power loss (need help troubleshooting please)

[trevarthan]

Granted, I haven't set the idle yet, but a quick check with the timing light and the vacuum advance disabled indicates 14 degrees before TDC.

The plate under the hood says 4 degrees BTDC, but I see a lot of people on the forum here saying 12 to 14 is fine.

[68 P.O.S.]

Originally Posted by trevarthan

I've tested the vacuum advance on the distributor with a rented hand held vacuum pump. Seems to be working (saw the lever move), but I don't know if it's within spec or not because I don't know the specs or where to find them.

Sounds like the diaphragm is good then. You can find the specs if you know what your distributor came out of. Likely a smogger with too much vac advance though. What are your plugs gapped at? If you don't already know, HEI gap is .045

Originally Posted by trevarthan

Granted, I haven't set the idle yet, but a quick check with the timing light and the vacuum advance disabled indicates 14 degrees before TDC.

The plate under the hood says 4 degrees BTDC, but I see a lot of people on the forum here saying 12 to 14 is fine.

Your timing is good to go. That 4 degrees is a factory safe number to keep warranty and recall issues to a minimum. Gotta protect that pocketbook. 12-14 degrees is a performance number which optimizes engine efficiency. Regardless, total timing is more important to set.

Still sounds like the carb needs a good cleaning and rebuild.

[trevarthan]

Originally Posted by 68 P.O.S.

What are your plugs gapped at? If you don't already know, HEI gap is .045

I replaced them yesterday with platinum plugs gapped at 0.035, I think. Will this cause problems with the HEI or is it fine? Can't regap platinum without chipping it, I've been told, but I can always toss them and buy regular plugs if those won't work.