[dirty_d]

I picked up my gt40ps today for damn cheap! I tore one head down today and cleaned the hell out of it. I think im just going to put the stock springs and rockers in my mustang into these heads with the stock cam. I pulled all the seals too, gonna replace those. Im not so sure about the exhaust valves. they were almost white, the seats look a little rough and they all have sort of a crack around the circumference of the stem at the top. Whats the deal with that?

[OZ_872]

My gt40p's were just like that, I just wire wheeled them and did new seals also. They turned out pretty decent, still working on getting the rest of the intake on though so not sure how they perform yet

[hotmustang95]

I once almost did the same thing until I had a talk with my mechanic. He is very particular about how he does things and since he's always been the guy to work on my car he told me to please please replace the worn out springs on these used gt-40 heads that I bought. He told me how much the 302 depends on the valve train working at it's best for the best performance. I ended up taking the heads in for a professional cleaning and new seals and springs. It leaves the heads and all the valves looking new. My car makes some great HP for the mods it has.

[dirty_d]

I wasn't gonna use the gt40p springs, I was gonna take the springs off my E7 heads and put them in the gt40ps. That would be fine for the stock cam wouldn't it? OZ_872, so that crack is normal? I was just gonna lap the valves to fix the seats, but those cracks are kinda disconcerting.

I was going to just use my E7 rockers too for now, so I'm not even sure if those can be used with stronger springs. I think I'm also going to try porting them.

[OZ_872]

That groove at the end of the valve?, I believe the retainers have a small ridge that seats into there, take a look at the retainers and see how they sit on there. We measured the spring pressure of the mustang springs and the GTP springs, I think there was only like a 10,000 mile difference between the two sets of heads. Overall, they basically came up to be the same.

[dirty_d]

I'm talking about that small black crack type thing that's like 1/8" from the top of the valve stem. The retainer cut is further down in the picture. Each valve on this head has the crack exactly the same, its open on one side and on the other its more closed. I haven't taken the valves out of the other head yet.

edit: i searched google images for explorer exhaust valve and found this, I can see the same "crack" that's on all of mine, so it must be normal. The exhaust valves are filled with sodium right? maybe that crack line is where the end cap or whatever goes in the stem.

[coreyflipp]

Don't take any of this to heart because I don't know what the hell I'm talking about, but I don't believe this has been mentioned. I'm pretty sure the gt40p ex valves have some sort of set up to where the rotate. I don't know if that groove is something to do with it or not. I think the keepers are offset .050" too because of this, so if you do use E7 stuff you might have to use the P's exhaust keepers. Google it and find someone who knows what they are doing.

[dirty_d]

yea I noticed that, they do rotate. the exhaust springs are also shorter than the intake, I'm not sure about the E7 ones. If worst comes to worst and shit doesn't work out, ill just get an aftermarket spring kit.

[OZ_872]

I'm not sure, I think mine had the same "crack" at the ends but I don't remember anymore.

[dirty_d]

I started doing a little mild porting, nothing major just cleaning up sharp edges and transitions with a dremel. I've also started smoothing up the combustion chambers and removing sharp edges. Maybe that will help get a little more timing without pinging.

[cleangtvert]

Mondello Performance Products-Head Porting At Home
Mondello Performance Products-Porting at Home

[dirty_d]

thanks for those links, I have a big powerful electric die grinder and carbide burr I was going to use, but it would be really cumbersome to use. Also being my first time, and how fast it removes material I didn't wanna end up going into a water jacket. The $25 black&decker rotary tool from walmart actually works ridiculously well. It removes material way faster than I thought, maybe because I've never ground on cast iron. After doing a whole head the grinding stone shows no wear at all, I figured I'd go through 10 to do both heads.

Here's a head I finished (only the chamber on the right is smoothed though). I smoothed the sharp transitions in the ports, leading into the chamber. The exhaust ports had the worst transitions, intake was already pretty good. I also removed the thermactor bumps at the end of the exhaust ports. I was able to really cut down the exhaust port valve guides and smooth them out, the intake guides were smoothed to a lesser extent.

[dirty_d]

I decided on the crane 44308-1 spring kit and 1.7 pedestal roller rockers. Hopefully tonight ill have the old heads off the car.

[cleangtvert]

i have the same springs and looking for a used set of the same rockers! i've got them on my gt 40 p's. i put about 16 hours or so in port work on the exhaust side only. diddnt want to put to much time in a set of irons from the j/y.

[cleangtvert]

few pics

[dirty_d]

I ground my valve guides to look almost exactly the same as yours there, I didn't take as much off up near the valve seat though. It kinda looks like you ground your valve seat into nothing in a couple places . The second angle is where it seats. Might just be the picture though hopefully. I just left the exits alone pretty much except for the hump because the inside of the headers is the same size. I can see why you want a used pair, it kinda hurts spending $240 on them when I got the heads for $165.

I got the old heads off today, it was a real pain in the ass getting everything clean after. I plugged up all the holes in the lifter valley and cleaned all the crud out. I cleaned the head bolt threads with a tap and the bolts with a die. I was real careful to make sure I wasn't removing any metal, which they didn't. The head bolts are the non-torque-to-yield un-flanged ones so I'm going to just reuse them. I cleaned the hell out of the block surface with a scraper and a brass wire brush followed by paper towels and carb cleaner. The new gaskets and gt40p heads are sitting on the block now waiting to be bolted on in the morning, I had to get some teflon pipe sealer. I disconnected the lower radiator hose, but the coolant is still up to the lower head bolt holes, I'm not really sure if its ok to put the bolts with the sealer in when its wet.

[cleangtvert]

i did nick two of the seats but they were going to the shop for a valve job anyway.i paid $50 bucks for my heads at the j/y, $160 for the springs, $180 machine shop.shit adds up fast. if i buy the rockers i'll have $600 in them.
good luck with the install. tell us howthey perform after you get it back together.

[dirty_d]

Today I torqued down the heads 72ft lbs on the lower bolts 80 on the top ones. I installed the rockers. I needed to use a shim on two of them, they took 3/4 turn to 20ft/lb after 0 lash, the two with the shims took about 1/2 turn with the shims. I had to trim the rockers on the exhaust valves with a file because the rocker body was contacting the spring retainer before the roller could touch the valve stem. Not a big deal, took about a minute to do on each rocker. I also got the headers bolted up, and the accessories and the lower intake on. I literally had to go through the bolt tightening sequence like 10 times to get them all to 25ft/lb. Tomorrow I just need to get the upper intake and throttle body on and then see how much of a problem I have getting the spark plugs in with these non gt40p headers, I think they're MAC. I can cut, grind and weld so hopefully there's enough room for me to make some kind of tightening device.

I understand you're supposed to re-torque the heads after running the engine and letting it cool down? I'm not looking forward to that because I'm pretty sure ill have to get the headers off again.

[cleangtvert]

tell me how bad it is getting the plugs in and out. i have the same headers also. yes they are Mac's. i allready have 90* plug wires.

[dirty_d]

I hope its not too hard. All i know is this would be a hell of a lot easier if I had a garage to work in. I've been doing all of this in the street, lol.