GT40P cc size?

[89stanglx]

Are they 59cc stock? What would the cc be if they're milled 16 thousandths? What are the advantages to milling them further?
thanks

 

[bmorrisj]

higher compression of course....but you may have to retartd the timing a bit and/or use better gas.... and check piston to valve clearance again, may not be milled much but better safe then sorry.... and if you dont have the heads yet, you need MAC tru fit shorties or MAC longtubes or FRPP "P" shorties....

 

[89stanglx]

I already have them on the car with FRPP P headers. How much milling are you guys running P heads doing?

 

[89stanglx]

Also, I'm still running the stock injectors. What fuel pressure should I be running? A little over 40psi?

 

[89stanglx]

ttt

 

[1Quik85GT]

If you mill the heads 16 thousandths..you will have a 57cc head...the P heads are 59cc stock...I would guess you would have a 10.5 to 1 compression motor...but you might ought to check you piston-valve clearance to make sure you have enough clearance. 7 thousandths equals to 1 cc when milling...good luck... those are good heads I have seen guys run low to mid 11s....

 

[89stanglx]

Thanks for the info. I've got the heads on the car with a tfs 1 cam and cobra intake. Im just running stamped rockers right now, but plan to install 1.6 rr's soon. So I'm fine one pv clearance.