The heads are dart pro 1,s angle plug,sbc,N/a,flatop pistons.

need sizes,heat,brand recomedations.

Thanks in advance
Keith

 

Lots of aftermarket aluminum heads these days are going to a plug type that uses a gasketed seat, long-reach threads but still the small 5/8" hex head. If your Pro 1s are relatively new (last few years) they will use this style plug.

Recommendation: Autolite 3924 or equivalent is what I use in my Darts and AFR heads. Also, check out Dart's website for plug recommendations which, if I remember correctly, will exactly cross-reference with the Autolite plug I listed, above.

 

IM using those same autolites (3924) in my Trickflows. And after a little plug reading. The heat range is pretty close. I like them better then the ACs i was using before.

 

Nice avatar.

 

Always start with a cold plug. It's better to foul out $10 in plugs than preignite and destroy an engine. I'd start with Autolite 3923 or Motorcraft AGSP22 (same plug, different stamp), put a couple miles on them and then if they're fouled go up one heat range to 3924/AGSP32. The insulator should be a light tan color. If it stays white you're too hot.