50tech.com

First of all I have an '88 Speed density lx hatch. I just got a explorer 5.0 gt40p longblock. I will be keeping speed density by the way. I need to know if I am going to have valve to piston problems with the gt40p heads. I'm not sure if the pistons are flycut like mustangs, it's a 2000 explorer engine. I want to run either the 15511 or one of the two xe264hr or xe270hr. Then I have some more questions. Should I run 1.6 or 1.7 roller rockers with these (stock pushrods). And should I get better valve springs. I want this motor to be able to rev to 6,000. My stock heads would only go to about 5,400 before it started to foat valves. Thanks for all the help.
Brent

You will have to do a clay test on the valves/pistons to be sure! I just put shaved P heads (58.5cc chambers) on my 88 GT and had plenty of room but that was with the stock cam. I could get by with .500" lift cam and stay within the .100" exhaust and .080" intake clearance that are recommended. NO need to run 1.7 rockers on the P heads - their flow flattens out at about 195 cfm at .400" lift.

Yea, if your goina take the heads off, some fresh new valve springs wouldn't hurt a thing.

I run all the way up to 6K with no valve floating and I am using the springs that came on the GT40P's, but then again the springs were new.

Agreed.

No point in really tossing on 1.7's. Stick with a good set of full roller 1.6's.

If you've got the heads off, wouldn't hurt getting set up with new valve springs.