Technical Sticky flathead valve

I have seen this topic before I had a problem, but couldn't find it again, so here goes: My 8ba 239 has developed a misfire and back fire. Replaced dist cap, rotor and plug and coil wires, also has a new coil, new plugs, but, the back cylinder driver side plug carbons up quickly. The other plugs look OK. What fuel additive and oil additive, if any, might help to free the valves? I don't want to pull heads yet if it can be avoided.

 

Joe: Read through the "sticky valve" info. posted on Fordbarn. Might help.
The Ford Barn - Search Results
Also, peruse this:
how to free a sticky valve flathead - Search
And: add a little Marvel Mystery Oil to your gas each time you fill the tank.
It helps remove carbon build up and varnish deposits.

 

I like Marvel Mystery Oil for things like this. Put some in the fuel and the oil.

 

Well it sounds like you have already used the parts cannon. Why not do a compression check and verify that you have a cylinder with low compression? Put some air in the cylinder and verify that you have a valve that isn't closing. That's probably the first thing I would have done. Sun Electric had a motto: "Test, Don't Guess".