OK, I finally figured out what was going on... My #5 cylinder wall was cracked... Ever so slightly... It allowed tiny amount of coolant to work its way into the crankcase as steam..
#5 spark plug would foul after 3 or 4K miles... No spark plugs available with hotter than stock heat range, so I added a .030" copper washer to the spark plug and that worked.
I finally installed a rebuilt 258.. No more problems with valve cover gaskets.. But, the rebuilder failed to notice a cracked water jacket near the water pump, on the side of the block... And yes I paid to have the block thermal cleaned and then magnafluxed.......
I was not willing to remove the engine for the rebuilder to repair so I drilled and plugged the 1 1/2" long crack..They at least provided the iron screws/plugs and tooling.
The new/balanced 258 runs very smooth.. No extra power, but with stock 1950 brakes...And now double original horsepoawer.. Not a great idea......
