Hey everyone. I’ve done a lot of searching and can’t seem to find the answer I’m looking for. I started out with doing a valve adjustment in my 79 620 as the top end was making a lot of noise. All rockers were at .018-.020 clearance. Tightened them to .010 on intake and .012 exhaust, engine hot. I’ve triple checked those figures to make sure it’s correct. Engine barely ran after that, back firing through the carb. Distributor had insane amount of timing retard, so set that back to 12* BTDC. Then set out to check cam timing. Made a chain wedge. Looked to be a tooth advanced.
Retarded cam 1 tooth, better but still rough. One more, still rough, one more, won’t run. 70psi compression, I’m on dowel hole #2. Should mention it has an aftermarket timing chain set (from before I purchased) both lobes are up at TDC on compression stroke, though maybe a little on the retarded side, like 9:30 and 1:30 vs 10 and 2. There is no V notch on the cam sprocket for me to line up to the slot behind it. But I just set it to be centered in that closest window with both lobes up. No idea what’s going on now or where to turn next. I notice the cam sprocket has a second set of numbers (1,2,3) on the chain side, was not sure if that’s for the chain alignment or cam alignment? Any help would be appreciated!u