A Few Questions

[Racerjoey1]

I just got my heads back from the shop, GT-40P rebuilt with tougher valve springs. My questions revolve around the heads. Over the stock E7TE's, what kind of changes in the power band if any can I expect. Also, will the P heads raise the compression over stock? I found a summit rebuild kit for a 5.0L for $269 that includes .030 over pistons, gaskets, all the bearings, oil pump, its supposed to be a pretty complete kit of parts. Anybody used this kit? I am gonna try to find a junkyard GT40 intake off of an explorer to go with my motor but that might come later. Also, the guy that did my heads said the valve springs were rated for about .515 lift. What should I set the red line at for my motor. I will be using ARP Main, Rod, and head bolts. I just need to get an idea of the RPM range I need to make a choice on a cam.

Thanks,
Joey

 

[90mustangGT]

Some Q's back at you

What CC rating are the heads? This will determine compression. 61 is stock, I think GT40's are either 64 or 58, the 58 will raise compression, the 64 will drop it. Have they been milled, and if so how much?

What kind of valve job was done on them?

Why do you need to rebuild the engine? How many miles? Does it consume a lot of oil, burn it, piston ring blowby?

Your powerband is going to be greatly effected by your camshaft. The "tougher springs" don't sound too tough with only .515 max lift, so you won't be able to go that agressive at all.

What intake to you have now? Your not going to get that good of gains with those heads unless you can feed them. An explorer intake would work well with that combo. The TMOSS ported stock lower would also feed those heads pretty good.

Either way, your powerband will shift north some, but it will keep on going to higher rpm's, it won't fall flat midrange like the stock engine does, but it's hard to say especailly if you put the unported stocker on there. Really, all you have now is the heads to put on, right? In that case I would just leave the stock cam on there. I had the stock cam in my combo with thumper heads, edelbrock intake, TB, full exaust and it pulled pretty good all the way up, not like the B cam but I had more bottom end.

 

[Racerjoey1]

The motor that is in the car is the original motor with 93k miles. It blows alot of blue oil smoke out of the tail pipes. I got a 40k mile short block and the GT40P heads with the car. I don't know what the max lift for the valve springs (they are a spring within a spring) is, but the guy recommended not to exceed about .515 valve lift. The heads have a 3 angle valve job and didn't need to be milled. I plan on getting the explorer intake before the motor goes in the car. I also want to do the cam regardless of whether or not I have the intake yet just because I only want to go inside the motor one time. I will probably just run the B cam because its affordable and tried and true. I dont care if its the absolute best thing in the world, I am in college and on a budget. BTW the Mustang isn't my daily driver so I can have the downtime with it while I save for parts.

PS- I also did a little research and found that the GT40P heads have a 58cc chamber which will bring a stock shortblock up to about 9.5:1 for future reference.

Thanks for the help,
Joey