Non seating valve?

[stomper]

OK, So about 2 months ago, I purchased a vacuum gauge, and diagnosed my Series IIA with a weak valve spring. (the gauge flutters quickly from 18-21hg mercury.) I adjusted the tappets, which were all very tight, and the vacuum guage settled down some, but it didn't fully settle in at a constant vacuum at idle.

Yesterday, I checked the vacuum again, and am getting the same problem again. The timing is advanced quite a bit to get it to run smoothly, and if I retard it down to 6 ATDC I seem to loose a lot of power to the engine. It still runs smoothly at idle at 6ATDC, but just no power.

I'm guessing I am getting some blow by in one of the valves, possibly due to carbon buildup from it running to far advanced. From others experience, would running some seafoam or MMO through the vacuum line possibly clear this, or should I just begin the process of taking the head off and regrinding the valves? The PO claims the engine was completely rebuilt not long before I purchased the truck (about 5,000 miles ago). The cylinders were overbored, and it has an 8:1 head.

[73series88]

hi
i would lapp the valves to make shure there seating well
just some grinding paste, a valve grinder and some elbow greese.
made all the difference in the world for mine.
good luck aaron

dont always take the po's word
heard that before

[Terrys]

Are you running with the timing 6 degrees AFTER TDC? No wonder you have no power. Your manifold and down pipe must be glowing red.

[stomper]

Oops, I meant Before top dead center. That is if the timing marks are correct. I had always timed by ear, but when I had the opportunity to put a timing light on it, I realized it was much too advanced. I set it with the timing light, (yes I removed the vacuum line and plugged it) and at 6degrees BTDC, it doesn't seem to have the power with it advanced further.