Ok so heres todays latest on being unable to time the engine with light because the mark is so erratic on indicator. While waiting for parts to arrive, I pulled all the plugs and did compression check. All cylinders between 190-200 psi. Plugs looked good, nice tan insulators. Re gapped them (AC Delco Rapid Fire 4) to .040 Today, put in new P3 ignitor distributor and Flamethrower 3 coil. Went right in where the old one was.. no issues there. I used black mechanical advance springs with no advance limiters. Set the internal rev limiter to 6200 rpm. 110 octane fuel in tank. Checked real good for vacuum leaks. None found. Only vacuum sources being used is the large one from rear of manifold to brake booster, pass side base plate port that goes to vacuum advance, and the front base plate port that goes to the choke diaphragm. Motor fired right up. Let it get up to temp and hooked the timing light up to external car battery and #1 wire. Again timing mark was bouncing everywhere but the engine idled smoothly and revd fine just as before. It did respond to turning the distributor as expected but I could not get a read on timing no matter where I put distributor. I then tested vacuum by connecting vacuum gauge to the booster vacuum port. Needle read 16Hg of vacuum at idle. Needle stayed put and did not move at all. I checked the idle mixture screws on Holley and they were both turned out 1.5 turns.
So no what? Could this be a valve lash issue? Im stumped at this point.. Stock L78 solid lifter motor with less than 5k on the rebuild.
