GT40P heads and 1.7 rockers ?

[Ninety5five0]

Hi all. When i was searchin on google i found alot about gt40P heads on these forums. I have gt40P heads and i'm gettin ready to install them. Along with a trickflow stage 1 cam. Will 1.7 rockers work with stock valve covers ? If so, can i still use stock size pushrods ? Thanks

[1989GT]

I used the stock valve covers but I had to take out the baffle for the oil fill and grind down the mounting area for the baffle with a dremel tool. Took about 5 minutes or so. You may get by with just taking out the baffle though. You'll have to check push rod length when you assemble the motor, each one is different, I used the stock pushrods with no shims under the rocker arms.

[Ninety5five0]

I already bougt some pushrods, they are stock length. I talked to a guy who has a 95 5.0 also, and used P heads, he said he used 1.7's and stock pushrods and it all works out for him. He also used his stock valve covers. The only difference is our cams, i think he used a e303 and i got a trickflow stage 1. I'm not too sure if that'll make a difference or not. Will it ?
He told me i can use 1.7's from a 94-95 cobra. True ?

[Coupe50h]

I have 1.7s and e-cam, on gt-40 heads, I removed the baffle, but didnt have to grind anything.
I also used my stock pushrods with no shims under the rockers, the pushrods all look the same size to me, i made sure they were not bent and reinstalled them, been running good, except for the sewing machine noise those rollers make

[1979bruiser]

you will probably have valve clearance issues if your using stock pistons. other than that i think you will be very happy w/ the gains from your heads.

[rwhite65]

I have 1.7'S with my e7 heads, stock pistons, and Trick Flow Stage 1 cam. I also have stock length pushrods but I used a set of aftermarket valve covers. I hope this helps.
Ryan

[Unit 5302]

Stock GT-40P heads actually lose flow after .500 lift... why you want to increase the lift of your valves by adding 1.7:1 rockers is beyond me.

Also, I hope you have upgraded valvesprings in them, the stock GT-40P springs are only rated for .500 lift which means if you didn't opt for better valvesprings, you'll probably have binding with that cam/rocker combo.

[Ninety5five0]

Yea the springs are upgraded, they are good up to .600 lift. So i should stick with a 1.6 rocker ? Stock size right ? 1.7 gonna give me too much lift for those P's ?

Heres what the specs say for the heads :

ford gt40p cylinder heads with all new parts. features 1.940/1.540 stainless high flow valves 60cc chamber hi performance spings ( .600 lift ) pc seals, hardened locks/retainers and seats 5 angle valve job CBN finished deck. Pedestal rockers required. Heads are fully assembled and ready for install


Will these flow bettter or just the same as stock gt40p heads ?

[tmoss]

Tthe benefit of 1.7 rockers is more in the faster opening rate and slighty longer VALVE duration (as oppesed to cam duration which does not change) for P heads. I ran 1.6s at first and swtiched to 1.7s later - it's worth some power. Have not been back to the dyno to prove how much yet. Ask any truely knowledgable racer about exceeding the peak flow point in lift, and he will tell you it's often beneficial. The P head flow rate levels off more at .500" than falls - it only loosed a couple of cfm. Get that valve open faster and longer, power will follow.

[Ninety5five0]

Will i be able to use stock vavle covers ?

And i'm not too sure if i'll have piston to valve clearance issues. My cam is .499/.510 . Its the trickflow stage 1.

[1989GT]

Will these flow bettter or just the same as stock gt40p heads ?

I would say that those heads will flow better with the bigger valves(atleast some due to the valve job) but you really need to port the head to take full advantage of the bigger valves.

Will i be able to use stock vavle covers ?

Yes, but you may have to do a little work to them.

And i'm not too sure if i'll have piston to valve clearance issues. My cam is .499/.510 . Its the trickflow stage 1.

With 1.7rr that's .530/.542, I know there are a few guys running the stage 1 cam with 1.7's with out any piston to valve clearance issues. But the only way to know for sure is to check when you assemble the engine.


TFS-51402000
Valve Setting Intake: .000 in.
Valve Setting Exhaust: .000 in.
Advertised Duration (Degrees): 275 intake/279 exhaust
Duration at .050 in. Lift (Degrees): 221 intake/225 exhaust
Camshaft Lift: .312 in. intake/.319 in. exhaust
Valve Lift with 1.6 Rocker Arms: .499 in. intake/.510 in. exhaust
Lobe Separation (Degrees): 112
Intake Cam Timing at .050 in. Valve Lift:
Opens 3 degrees BTDC
Closes 38 degrees ABDC
Max lift: 108 degrees ATDC
Exhaust Cam Timing at .050 in. Valve Lift:
Opens 49 degrees BBDC
Closes 4 degrees BTDC
Max lift: 116 degrees BTDC
Firing Order: 1-3-7-2-6-5-4-8

[rwhite65]

Originally Posted by Ninety5five0

And i'm not too sure if i'll have piston to valve clearance issues. My cam is .499/.510 . Its the trickflow stage 1.

Read my post above
Ryan

[Ninety5five0]

I thought that the valves were set lower or closer to the block or pistons than e7's. Not positive tho. I'm pretty sure P heads have a higher compression ration than e7's too, so wouldnt that mean the valves are closer, or its a lower sitting head ?

[1979bruiser]

its higher because of the spark plug boss is closer to the valves and extrudes into the chamber, not set in the chamber on e7's. so that would mean that the valves are in the same spot as e7's- pushrods are the same length , valves are the same length and rockers are the same. if any of these were off it would throw the geometry off for the rockers.

[Ninety5five0]

So if someone with a trickflow stage1 cam and e7 heads with 1.7's has no problem with valve to piston clearance, that mean i'll have no problem with a trickflow stage1 cam and gt40p heads with 1.7's ?

[tmoss]

No it does not...........you have to measure.........

[1979bruiser]

im not saying that there is enough clearance, just saying that the valves are in the same position compared to each other.
i agree w/ tmoss-you have to measure.

[Ninety5five0]

I'm just gonna stick with 1.6's to be safe. Anyone know what size bolt mounts pedestal mount rockers on P heads ? I need to go up to summit today and get some rockers, but i'm nto too sure of what size bolt it is. Thanks

[1979bruiser]

are you looking for bolt size and tread mount?as for the rockers they are the same as your 5.0, just look them up or order them as if you would your stock heads (if your ordering over the internet).if you talk to a sales rep they will know if you call it in your order.

[Coupe50h]

I would go 1.6 anyways, but the gt-40 p head should be a bigger cc chamber than e7's, and unless decked at a machine shop, the p's are like 65 cc, so you have all kinds of room there, when you mill a head down real far, you always need to check pushrod length, but that is my opinion only, not proven facts or anything.
my heads were milled like .1000 so i just adjusted my rockers accordingly, and had some shims just in case, but i didnt need any.
good luck