I'm trying to find out how much to gap my spark plugs and as always, keep finding 10,000 different answers. I have a b18c with 12:1 JE pistons. I've read that you're supposed to gap the plugs a bit smaller with them, but i cant find out how much smaller. Thanks

 

ALL MOTOR section will offer better responses, but here is my response. There is no one size fits all. More importantly with 12:1cr a colder heat range plug is needed. Then the plug gap comes second. You may be ok with the factory gap. Hope that helps.

 

I hope so too lol. I'll just have to figure it out by trial an error

 

I've had good results with a 7 heat range plug gaped between "0.034 and "0.037
They were used in engines with 11.8:1 and 13.7:1 both on stock ignition.
If you upgrade ignition I would suggest "0.040. Best way to find out is to have a few sets ready at the dyno and see what makes the most power. I picked up 5HP by going with a bigger gap.
Good luck.

 

I'll wait til i get a tune for all that haha. I just kept the stick gap for now