Aftermarket cams in a PI engine

Wyldhorse · Apr 3, 2011

A while back when I was looking at cams (Comp 278AH...I love these cams), I found out that I'd have to have the pistons fly cut to run these for clearance issues.

Is there a difference in the pistons in the PI engines? Could I get aftermarket cams and not have do do any other internal work other than possibly stronger springs?

I'd love to be able to cam the car without having to do a bunch of supporting mods right now. I think when or if it's possible to do cams without any internal issues, it'll be at the same time as the 4:10's, headers, and the 5spd or stall goes in.

MadStang · Apr 3, 2011

I'm running Houston Performance 292's in my Roush... You don't need to fly cut the pistons, just find the best setup for your needs.

The HP292's don't require a valve spring upgrade nor do they require fly cut pistons. They work with all the OEM valvetrain.

http://www.youtube.com/user/sparatic03#p/u/25/rfZj_W2sVt8

duff daddy · Apr 3, 2011

There is a difference between a 96-8 and 99-04 piston. A smaller dish on an NPI piston gives you a higher CR when matched with a PI head rather then NPI and PI from the factory. I ran comp 270's in my car, you dont need to have valve reliefs, however you do and should always degree the cam shafts.

Wyldhorse · Apr 3, 2011

Duff Daddy said:
There is a difference between a 96-8 and 99-04 piston. A smaller dish on an NPI piston gives you a higher CR when matched with a PI head rather then NPI and PI from the factory. I ran comp 270's in my car, you dont need to have valve reliefs, however you do and should always degree the cam shafts.

so if I wanted the 278ah's all I would need is the springs and supporting mods to compliment the cams (gears, stall or 5spd etc) then of course a tune...aside from anything needed for cam installation/degreeing?

Wyldhorse · Apr 7, 2011

turns out, even with the this motor, the pistons have to be fly cut for the 278ah's

duff daddy · Apr 7, 2011

Yea you wouldneed to notch the pistons. Look on the other thread about cams in teh 2v section, I posted a picture of my short block to show how it should look.