68 mustang poping under load

I have been trying to figure out what happened to my motor for a while now. I have a 68 mustang with a 302 block .30 over stock 4v heads with bigger valves not quite sure of the size. MSD AL6 and PRO billet distributer,268hxe comp cam with stock rockers, performer rpm air gap intake with a 600cfm holly double pumper.

I went to the track about 4 months ago and ran a 14.082 at 98mph best time my car has run. The day after i think i may have over revved the motor and valve floated it. After this I had noticed that when down shifting it would pop loudly and under full throttle it will also pop while still increasing rpm. I am thinking that i may have messed up a lifter or wiped a cam lobe. Since this I have re jetted my carb in any hope that something may have go wrong with it i put it down to a 64 primary and a 72 secondary with a 6.5 power valve. It is now idling very rough and some times stalls. I am thinking that there is a bigger issue like my cam any suggestions on what to check.

Could be you now have a bent valve head. One of which tapped the top to a piston during that "Over-reving" sequence back a few days ago.

Or, (not likely) the clearances for the valve stem to guide got tighter and is slowing things down some.

Either way take a compression pressure check to see which (if any) cylinder may now be down a bit.

Car engines can still run good on 7 or 7 1/2 cylinders, but run better when all eight are firing off properly.

Not fun, and not cheap either, depending upon results.

Wm.

I had a similar problem with my 351 build and a Model 4160 Holly square bore. It kept popping through the exhaust after warm up, and occasionally through the carb. Turned out to be the float in the primary side was allowing fuel to dripple into the carb because the fuel level was too high. I had adjusted the thing all the way down, but it was till at the top of the view port. Had to bend the brass tab on the float. I have no idea how it got knocked out of adjustment.

Chech the easy things first:
carb float levels? (doubtful)
rear carb linkage?
bent pushrods?
sticking valves?
Pulled studs?
flat lobe on cam?

Thanks guys for your help I found the problem wiped cam lobe and the lifter is shot also guess its time for a new cam.

Are you planning on using another Comp cam? Now I am not bashing Comp cams but, I use a lot of different forums and it seems their name comes up a lot when it comes to cam failures.