I spent last night cleaning up my AFR heads. They had the carbon buildup of 250,000 miles and only went 20,000. The old motor ran poorly. (duh).

I put one of them on the engine but may pull it off to clean the intake valves. You can see them through the intake runner and they are super nasty. That can't be a good thing.

I used a wire brush on a drill to clean the combustion chambers but there is still some carbon around the valves. Should the valves be removed and all that crap cleaned off?

 

Send 'em to a machine shop and have them disassembled and hottanked.

 

And put a catch can on there when you get it back together to keep oil out of the intake which should help with the carbon buildup.

 

AFR does not seal their rocker studs out of the box, you might be sucking oil out of the top of the head into the port.

How many miles are on the bottom end?

 

I bet you're on to something! I removed two of the intake valves today and it was all I could do to remove the build up w/a wire brush on a drill.

30,000 on the bottom end.

 

Gasket remover took the carbon right off my pistons, you might want to try that.

 

I checked each rocker stud to be sure they weren't leaking into the intake. I did it by filling the threaded hole with brake cleaner and looked for leaks.

None found.

I guess it happened (the fouling) when the fuel return line was plugged.