GT40P heads on non roller 302

[Scott Peters]

Hi all,
This is regarding my 84GT 4barrel car.
Stock Ho cam with 86-93 shorties and cats.
My questions are:
1)-If you try to put this on a non roller motor like mine,
Do you have to change the valve springs , and if so,
Which ones would you use.

2)-has anyone here tried the E-bay GT40P oversea’s
Shortie headers?

3)-Are these heads worth it?
Is there any noticeable improvement on an engine like mine?

Thanks for any and all input,
Scott

[bwguardian]

I have the GT40p heads on my 85 GT and really like them. They were fresh out of the machine shop when I installed them and have stronger springs, but I have the E303 cam. I suggest you do get better springs given the time to do so is while they're off the engine. If you're staying with the stock cam you could install some 1.7 rocker arms to help. I used a set of BBK shorties when I first installed them, so I had a couple plugs that needed the 90* boots. I later found a set of Ford Racing stainless steel shorty headers which work well. I've heard the cheap Ebay units work, but not sure how well...

[Scott Peters]

Thanks for the info.
If I’m not mistaken, isn’t 85 the 1st year of the roller cam 5.0’s ?
Also, were you able to keep the air pump function for the cats?
My main concern with this possible upgrade, is using the right valve springs.
Wasn’t sure if I could use 84 springs since it’s not a roller cam.
I like the stock cam as it really comes on strong down low and it’s all done by 5000 rpm’s.
Thanks again!

[bwguardian]

Thanks for the info.
If I’m not mistaken, isn’t 85 the 1st year of the roller cam 5.0’s ?
Also, were you able to keep the air pump function for the cats?
My main concern with this possible upgrade, is using the right valve springs.
Wasn’t sure if I could use 84 springs since it’s not a roller cam.
I like the stock cam as it really comes on strong down low and it’s all done by 5000 rpm’s.
Thanks again!

Yes, 85 was the first year for the roller cam and last year for the carburetor. I have an off road X-pipe, so not cats. I did keep the smog pump...but it's gutted...for the simplicity of using the oem accessory belt and/or routing. You'll want to set the valve spring pressures according to what cam you're running. Can't remember what the open and closed settings were for the E303 cam, but it has plenty of power right off idle and pulls hard all the way past 6,000 rpms. The tires will break loose with any decent throttle in first gear, but I do have an 8.8 rear end with 3:27 gears. I would get new valve springs that at least have the damper and set them up with the proper open/closed pressures.

[Bentley]

Whats your goal here and what do you use your car for? Daily driver? Race car?

[Scott Peters]

Bentley, it’s a toy that gets used on warm day .
It gets some Auto-X use, and it’s set up for handling.
My inquiry was more of a “ once these stock 84 heads need rebuilding,
Would it be possible to use the GT40P heads, which seem to be available
everywhere.”

From some further research, it seems I will lose the air pump locations
on the back of the heads, not to sure how this will affect my Cats.
But mainly, would it be worth anything in power gains, given that I would
Probably have to change to non roller cam valve springs.
It was more a question of “ anybody done this before “ on a non roller 302, and what was the outcome.
Scott

[Bentley]

Reason for my question is if this is a " daily driver" in my opinion it would be a waste of time..
Interesting question, P heads on a non roller cam engine, that I would think should be no problem.. I would guess new pushrods ( after measuring for the correct length ) would be my guess.... but I do not know for certain.....
I did install an explorer engine in my 83 using the P heads on it... I had a set of the chinese ( Fits P head) on it and I think they fit and looked well made...
I used Alex's parts for the beehive springs I installed on my heads....
EDIT: Wrong pic and I cannot figure out how to delete it..

[bwguardian]

The GT40p heads will give you a bump in power...mainly through a compression increase relative to smaller combustion chambers. Since you're putting them on an existing working engine, it shouldn't matter roller versus non-roller motor.

[Scott Peters]

Bwguardian,
Thanks for that information.
My concern, was that I thought roller cam motors had a higher rate valve springs.
And that since I was thinking of using these heads on my non roller cam 84, that it might wear out the stock camshaft.
Am I totally wrong on this assumption?
My stock 302HO,never see’s north of 5,100 rpms, as there is nothing left at point.
I love the low speed torque that it has now.
Scott

[mcb82gt]

gt40p heads need new valve springs anyway. they are too weak on a HO motor.

[Zap's 85 GT]

Even stock P heads have very weak valve springs. Even with the lame torque cam of the Explorers, mid 4k rpms is really pushing it for the springs. Alex Parts is a good place to purchase drop-in spring kits for these heads.

https://alexsparts.com/sbf-e7-gt40-gt40p-spring-kits/

[Scott Peters]

Thanks for all the info guys.
I now feel “well informed “
Scott