Ya gotta remember that these only had at Most from factory 8.5.1 compression.....that's NOT alot of compression. My 292 had 95 pounds in all cylinders and ran perfectly fine. Here's some general specs for setting timing:
8-10 degrees advanced No vaccum
20-25 degrees at idle with vacuum.
And no more than 38 degrees full load. You said you had it set 17 Btdc? That tells me 17 degrees retarded.....you should have it Advanced not retarded. Try 8 degrees advanced and see what happens. Heck I had my 292 at almost 16 degrees advanced with no problem because the compression was so low. With my new 292 I'll be starting at 8 without vacuum and tuning from there.
Tonight's experiments, had success, or at least I'm back to where I was before. The first two experiments yielded an awful running engine, no power at all, tons of backfires.
1) Backed idle mixture from 1-3/4 to 2-1/4. Previous setting was 2. No change, lots of backfires.
2) Swapped top and bottom vacuum lines off the carb so that advance is on the top, transmission on bottom. Idled worse, no change, lots of backfires.
3) Bumped timing up
17 no vacuum
40 with vacuum!
50 with vacuum at higher RPMs!
it could be that the timing light is a little bit off, it's one of those with the knobs to measure the advance where you set it to the number and the strobe lights at 0. I know it's not retarded because I watch the advance go up when I connect vacuum and increase the RPM.
The great news is that there were
zero backfires and only small hesitation. The performance was markedly better than the previous runs. I didn't hear any knocking, but then again, only took a short run around the block.
I think I'll try backing off the valves on all the cylinders like suggested in the other thread. But this weekend i'll try my 0-60 to see if the HEI made a difference.
The most troubling of all is that my friend's college-bound son, who's a big old car buff, stated afterwards he wants an old Mustang. I've gotta work on that boy...
Mark
