Hello Guys, I am new to the site so please have patience. I have a new 383 stroker that was professionally built by a race shop in Arizona. Running, big cam, 1.6, roller rockers, 9.9 to 1 compression, ARF ported and polished heads. Engine came with a 780 quick fuel carb with 6.5 power valve, 72 jets front and 84 rear. Engine runs great but at about 100 miles or less the plugs are shot to the point to where it will barely run. I have jetted down to where the engine runs out of fuel on the top end (6200rpms), went down one size at a time on the power valve all the way to 2.5 and no matter what combination I go with I still foul out the plugs on the rich side at about 100 miles or less. I even put a 6al box on it with a high performance coil and gapped my plugs to .055 and again it runs great for about 100 miles then plugs are shot. Recently put a new quick fuel 650Q double pumper on it with 68 jets front and 76 rear. Runs great but after only about 30 or 40 miles it looks like the plugs are starting to foul already. Can anyone offer any suggestions as to what I need to do next. Been working at this for months now and cant get the right combination.

 

Wow, No ideas at all. I thought surely someone out there could give me some info???