i am building a big four 2.6l ,48 ida, msd,for racing
what spark plug do i use ?
hotter or cooler then stock?

Sorry to be a smart ass but you haven't built the engine yet and your wondering what spark plug to use?

I would worry about plugs after you get it running. You gotta lot of work ahead. Good luck.

Paul

(I smell a fish here)

As for being a smartass:

It would be kind of difficult to get plugs AFTER it's running, now wouldn't it?

Maybe you need to re-read the question.

Paul

And I thought someone was going to blurt out, "HEY! Use some Splitfire Quadtriple Tip Platinums! They look SO COOL!"

I agree ... let's get it built & broken in first, maybe with some NGK BP6ES plugs to start?

I'll bait it on.

If ya got a hot running engine use colder plugs and vice versa.

I would start with the NGK BP6ES also

yea, get those pistons in those jugs first, and tweak the points

joe, your avatar is killing me.

I've been staring at it (them) for the last hour.

Paul