Originally Posted by ColeJohnson
I'm pretty sure it's because mod engines have aluminum heads, right? Can't just tap it. You have to grind it out then put a sleeve in it, then tap that with new threads. At least, that's what I understand. Someone correct me if I'm wrong.
That's not it. You can tap aluminum just the same as any other metal.
Alll they are doing is the same as we do on aluminum pushrod engine heads.
They are re-tapping the spark plug hole and installing a "heli-coil" or "thread insert" and sometimes a new seat.
The cost is higher because of the specialized (i.e. longer) tools required.
What a rip off.
You mod motor guys need to get together in clubs or whatever and just buy one "kit" that you can share.