What would need to be done to make these heads work on an old windsor? I've heard of people getting significant benefits from these sorts of heads and was curious if anyone knew what needed to modified (if anything). Are the 40p's aluminium and the 40's iron?
Haven't I seen you some where else? Both heads are iron, both heads will bolt on OK (to an early 302 anyway), both heads require late model rockers. GT40Ps flow better up to 0.500" valve lift where GT40s are better over 0.500". The other issues you will encounter are that with the GT40Ps you will need custom made extractors to fit into a Mustang (I had Pacemakers and they fouled plugs on both sides). If you go with GT40s, they have larger combustion chambers so may need to be milled down some.
I went for GT40Ps because I'm more interested in torque and drivability. If you're building a hotter motor with more than 0.500" lift cam then the GT40 heads may be a better choice.
I can't comment on power/torque increases as I haven't got the car back yet. I'm getting extractors made in the next week or so.
I am not sure but do the 289's have valve reliefs in the pistons. If not thisre may be problems because the GT40 and GT40P's have larger valves. As COV3R said, with the GT40P's you will probably need different headers but there seem to be plenty of GT40P specific headers available in the US, but it is worth it for the extra power and drivability the GT40P's will give you. One other thing, the GT40P's actually flow the same on the intake and more on the exhaust compared to the GT40's at high lifts., so they are by far a better head IMO.
Just wondering if anyone else has had this problem.
I am currently running a 347 stroker with GT40p heads in my XP ute, when i had the motor built i fitted brand new GT40p Heads to it. The standard valves have a fault in them (may not be in all batches) as i found out after doing only 50 kays. They are hardened to far down the stem and tend to snap the top of the valve (around the collet). This little problem caused $3000 damage, I had to replace 1 KB silverlite piston,buy a full set of moly plasma rings,resleave a cylinder, have the rod and crank rechecked and smooth the chamber in the head back out. Needless to say i now run Manley stainless valves. So it may pay to check or replace the valves before fitting these heads, especially if running a high lift cam.
From my dealings with an engine runing e7 ported heads with gtp valve gear..This set up including gtp springs, keepers and retainers are NOT up to high lift and rpm..This engine had 2031 Crane cam and 1:72 rockers..Which is possibly why valve head broke off as well...They're just not designed for this sort of treatment...
$3k would have got you into some NICE heads and valve gear too!!! Hope all is well now...
Engine runs sweet now and revs well, when the valve shat itself we went over the engine with a fine tooth comb. We thought that the valve must of contacted a piston, but all clearances were fine. The fellow that built the engine has some contacts in the Brute ute game and they had said that it is a problem with those heads. Wish i had of known that before i put them on the engine.
Falconsrock - how much lift in your cam? From what I've read these heads dont work too well (stock anyway) with much over 0.500".
I'm only running a very mild cam with mine. 204/214deg, 0.448/0.472"lift. Here is a good tech article on the subject.
My cam is not wild either as the car is daily driven
Peak cam lift:.297"/.310"
Peak valve lift:.445"/.465"
The engine runs at 10.3:1 compression. It has been mildly ported and now runs oversize manley valves and roller rockers. Unsure on horsepower/torque as i have not dyno'd since head rebuild. But it goes well enough for me. It is in an XP ute which are a light enough vehicle and without tubbing them you cannot get decent tyres under them anyway, although this is fun it is not much chop in the traction department :dj:
:fraz: Just found this thread and am a little concerned as to what the future might hold now... I'm about to fit a Crane 2031 cam, 1.7 RR and heavy duty crow springs (and a rollmaster timing chain, new valve retainers, locks, seals etc) to a series 1 AU. Am I at much risk of rooting the engine (heads and block are stock)? I get the impression this is not an uncommon setup and haven't heard of anyone having problems up until now.