Ok So I'll Try A More Techinal ? To Peek Interests, Valve Size And Valve Reliefs

[90lxwhite]

So, I'm wanting to go gt40 heads and Im currently running e7's. My cam and piston specs are below however I couldn't find the size of the valve reliefs on the pistons and I couldn't find a site of the manufacture (speed pro) I could only find retailers, summit, jegs, etc. With my cam of .512 lift should do you think I will have ptv issues with the gt40's as where I don't with the e7's or are the gt40 valves that much bigger that I will run into problems? Im ready for the response "one should always measure" before install but I don't want to order a set of heads that most likely will need piston notching since I'll have the car torn apart only to find they are not going to work. It's not like I can run to walmart to exchange em for a different set.... Anyways here are the spces,, thanks for the replies, lately I've only been getting views. Oh and I get it the gt40 head thing has been beat to death but c'mon guys has anything new happened with the 302 in the last 20 years!? Also I think speed pro was bought by china hence the no corporate website. One final question before I let yall go, will springs from an e7 work on the gt40 head? My e7's have better springs than whats offered on the heads and I want to reuse if I can (beehives)
Comp 35-440-8
2000 to 5500 operating range
281HR cam grind number
281 duration in (advertised)
281 duration ex (advertised)
220 duration in @ .050
220 duration ex @ .050
.
512 valve lift in
512 valve lift ex
110* lobe sep angle

Speed-Pro Hypereutectic Pistons ZH120CP30
Bore (in):4.030 in.

Bore (mm):102.362mm

Piston Style:Flat top, with two valve reliefs

Piston Material:Hypereutectic aluminum

Compression Distance (in):1.615 in.

Piston Head Volume (cc):+5.00cc

Wrist Pin Styleress-fit or floating

Pin Diameter (in):0.912 in.

Piston Ring Thickness:1/16 in. x 1/16 in. x 3/16 in.

 

[90lxwhite]

Dang stangnet.... threads been up 20 min, ten views, no replies.... Where did all the people with the answers go?

 

[90lxwhite]

3 more views

 

[RangerJoe]

A custom cam maker could probably give you an accurate answer, knowing the cam events. Most of us can only guess at it, it will require checking. That said, it doesn't appear to be a very aggressive cam, i would believe you will be okay. Also, if you have springs designed for oem style ford heads, they should work on the gt40's as well. You will need to make sure they are installed at the correct height and have the correct spring pressure.

Joe

 

[revhead347]

You should be fine. I've ran a .512' lift with 1.90" valves on a stock piston before with no notching. The SpeedPro pistons have decent notches in them. They are sold under the Sealed Power name which is a subsidiary of a bigger company. I believe it's the same company that sells the TRW line as well. Not sure on the springs, but the cam card should have spring specs that you can match up on it.

Kurt