If the exhaust valve is not working (for whatever reason) that would contribute to the carbon fouled plugs. It would be easy to back off the #8 rocker arm (when the intake valve is staring to close) in order to see if the push rod is straight.

If it's bent, well that would be an easy fix. But, usually there is an underlying reason the push rod is bent. In my case (early years) it was due to missing 3rd gear:3gears:

You could say I broke some parts while honing my craft:grin:

The exhaust valve not opening enough will cause a backfire thru the carb, as the cylinder IS getting gas and firing, but the burnt gas can't get out of the cylinder, so it will back up into the intake when that valve opens.

The pushrod is definitely straight- I pulled it and looked at it.

Well, I finally yanked the intake. The cam is trashed Cylinder number 8s exhaust lobe is definitely round and all the others have pitting on them. I think I caught it before sending trash too far through the engine, so I guess the plan is to pull the cam, confirm the grind, get a new one (If it's COMP I'm going to avoid that and have Crower or Isky grind an exact duplicate of whatever's in it. My friend highly recommends either and I've been hearing far too many horror stories about Comp lately), and keep a very close eye on the oil when I get it running and follow the break in to a T.

Engine Issues...
 

While you may get away with a cam/lifter swap...a prudent approach would be to check all the internals for any possible issues. Pulling an engine isn't fun, but it is cheap insurance in the long run.

Double roller steel chain and gears are a must...you might also want to check valve train items [springs, keepers, retainers, seals].

Given the legacy of the car...not a good time for shortcuts.

-wilma

There has been plenty of metal shavings in the oil from all that damage. I'm on the "pull the engine" wagon and remove the pan and inspect all the bearings. If the crank isn't scored but there is shavings in the bearings, you can get away with just replacing them.
If the cam is an old school, long duration build, there are better grinds available now that will help the engine have more vacuum and the same or better power range than what is in there.

Sorry you have to deal with this. This problem has become all to common in the past several years and especially recently.
I have a 20 year old Comp 280H in my 496 that sounds cool but is a pain in the butt to drive on the street. I'm going to be looking at a hydraulic roller conversion for next year.

Agree with the others, for a permanent fix, you're talking about pulling the engine, disassembly, inspection, and likely a rebuild. The missing metal had to go somewhere and that means the oil, into the bearings, etc. No quick fix here unless you want something short term, but think you're in for a rebuild, or pull the engine, set it aside and drop in a running unit until time / funds allow a proper rebuild if that engine is something worth saving.

Also, probably smart to disconnect the battery before proceeding further.

bingo!!

Glad you found the problem.

Yeah I think if you plan to drive this car a bunch I'd lean towards pulling the engine and checking the bears since some metal has run through it.