The 96-mid 97 Explorer/Mountaineer 5.0's had the "regular" GT40 iron heads with the larger 1.54 exhaust valves and the std spark plug angle. The mid 97-2001 motors had the "P" heads. The early GT40's have three vertical bars cast on the end of the heads, the "P" heads had 4 bars. The early ones also had "GT" cast in the lower corner next to the valve cover on one end (front on passenger side, rear on driver's side) The "P" heads either have GTP there or just "P" (not sure, never bothered studying the "P" heads up close) Now, you will have a slight drop in comp ratio with either unless you mill them some to get the 64 cc chambers down to 60 or so which is what the chambers in your 69 heads measure. The GT heads have pedestal rockers, held down via a 5/16" bolt,, no studs in these heads. While they're not the strongest way to bolt down the rockers, they will handle a little more aggressive cam (lift and duration) as will the roller cam valve springs I've run them with Cobra roller rockers and a B303 roller cam without problems, others have used even more cam. The B303 with 1.7 rockers gets the lift at the valve to .510

 

. More power than World Windsor Sr's? ... YES!... The article was Junkyard Jewel 351W part 2 in May 2000 HotRod mag... they even milled the Sr.'s down from 64cc to 58cc to give more than equal compression ratio and the iron GT40P's from Exploders still gave more HP and torque... from better shaped ports and even faster burn chambers... the article isn't available online (I have all the mags), but the same thing is said in this thread and others...


max cu in for GT40P heads? - Ford Muscle Forums : Ford Muscle Cars Tech Forum



. The articles compared SBC 350" and 351W builds, but the 351W was handicapped by using the nasty TRW/FM/SealedPower/SpeedPro 336H pistons with 4 valve reliefs cut out through the sides of the piston tops and low compression height compared to the 2-eyebrow KB's on the SBC... even though KB's were available for the 351W at the time, but maybe not in the catalogues yet... the Sr. heads really don't like compression ratio down in the 9's, either, 10.5-11:1 makes them work better... I remembered the articles since I have 351W and Sr. heads, although mine were well worked over before installing...


. Similarly, the stock SBC Vortec heads also outperform the Chevy SB2 over the counter racing heads with bigger valves from back in the day...


. BTW, the articles claimed the GT40P heads have smaller 60cc chambers... earlier GT40 heads have 160cc intake ports (GT40P may be ~170cc) and aluminum GT40X heads have 178cc intake ports... (Apparently Chevy and Ford both use 'X' to indicate about 10cc bigger intake ports)

 

What youre saying sounds good to me anyway. Small drop in CR isnt hurting anything, i dont want to pay 4.00 for gas. If i stumble into any explorers, i think ill go ahead (haha) and grab them.

 

I'll bet they did some port work on the P heads to achieve those results. Then that last sentence, you're mixing up stats on several heads. I did a search on the port volumes of the GT40 heads, the volume for both the iron heads (GT40 and GT40P) are the same 145 ccs, not 170 ccs. Now you're saying those small ports flow better than a 200 cc port volume ? As far as the "X" goes, that has nothing to do with the port volume displacement, it's just a suffix to denote a different head. Ford also made "Y" and "Z" heads as well as the "X" and "P"

 

. I think your info is wrong... 145cc is TINY ports...


. I just quoted the info given in the article... another thread I read here today calls the GT40P as 59cc combustion chambers by somebody who used them copying the magazine build...


. They said at that time the GT40P heads weren't available over the Ford counter, just as Explorer only service assemblies at $700 EACH... then they discovered Central Coast Mustangs got the bare castings, add S.S. valves, 3-angle valve job, and springs, and sold them for $639/pair... they didn't give any more details on them...


. Bigger port heads don't always flow any better... my World Windsor Sr. heads were claimed at 195cc when I got them about 23 years ago... the intake ports weren't too bad, but, stock, the exhaust ports are horrible, flow very little, and make the heads constipated... I pocket ported them, fixed the intake ports, hogged out the exhaust ports, radiused the valves and valve seats, and backcut the valves before ever using them... I had ported the stock heads that came on my '77 351W until I struck water and had to weld them back up... but the modified Sr. heads still provided a quantum leap in power over the ported stock heads...


. Chevy calls their SBC Vortec heads 170cc... but they usually measure more like 180cc... and they outflow their old over the counter SB2 racing heads...

 

I was thinking even 160 or 170 seemed pretty big for a stock smallblock head that was known for torque. I dont have a problem with the port size, and the article i read claimed the heads werent ported. I was thinking just blend the bowl and unshroud the valves a little as appropriate and throw em on. The car is alot lighter than i expected (3200ish for a smallblock car) but still want good midrange that will probably only pull to 5 or 5500. At a later date when i score an AOD i might do rod bolts and maybe screw in studs, rockers and springs. From what im reading theyre decent heads so even if i move to a different mill i could probably recoup whatever i put into em. Again, i really appreciate the input guys.

 

Not sure why you're injecting either of these two bits of info here. But If they used those Central coast heads, then they were not stock "as is" heads. If they went through the trouble to replace the valves, it's a good bet they got some extensive port work as well. The Chevy comparison ? That's a moot point. We're talking about a Ford head, not a Chevy head.

 

. Just saying the Ford GT40P heads, like the Chevy Vortec heads, may have bigger ports than the specs say...


. They didn't replace the valves in the "bare castings", there were no valves yet, so they added valves... no mention was made of porting, but assume there was none, just a decent 3-angle valve job...

 

I'm sitting here looking at my Canfield (p/n 20-450-58-1) heads along with a stock FelPro Explorer intake gasket and a FelPro 1262R intake gasket. The 1262R is slightly larger than the 192 cc Canfield intake port. The Explorer GT40 gasket port is shorter in height. Now you still want to tell us that the GT40 port has more volume than a 200 cc World SR head ? I'd post pics but cannot do it here. I also have a completely assembled roller 5.0 with the early (not P heads) GT40's on it, along with another set on the roller 351W in my 96 E150 van. I used the stock HO gaskets assembling the 351W when I did the head swap last year and those just did match the GT40 ports. (used them cause I already had them on hand and they fit) Can't recall but I may have also used the HO gaskets on the set on the 5.0. At any rate the stock GT40 intake gasket port opening is smaller than the ports on my Canfields.

 

. Re-read... nobody said the GT40 ports were bigger than 192cc ports or 200cc ports... I think you're just trying to be overly-argumentative...

 

And I'm not the one trying to imply that stock unmolested GT40P's out perform heads that flow more either. On a bigger displacement engine at that.

 

. Me neither... it was May 2000 Hot Rod magazine... send them a nasty email... LOL!


. While here talking the 'magic' GT40P heads, I'm simultaneously explaining to someone how to build a SBC 350 using the 'magic' Chevy Vortec heads, as well, and getting poopoo'd over there, as well:


SBC performance marine? - Page 5 - Hot Rod Forum : Hotrodders Bulletin Board
.

 

I got a new poser for you guys to consider. I just checked the price of aftermarket heads, and wow. Cant believe how cheap they are, was expecting an assembled set of generics to go for 800 and i can get tricked flows for 625. So now that im rethinking my whole thought process here.... anyone have any idea what kind of lift i could run before running into clearance problems?

 

. $625 EACH?

. Need to disassemble assembled heads and inspect them before using, so might as well buy them bare, buy known good parts, inspect them, and assemble them yourself... and not pay for assembly... and not get questionable, unknown parts...

.

 

Were 625 for the pair, the twisted wedge "fast as cast" which ive seen awesome reviews for. However, did some fine print reading, you "have" to use the twisted wedge pistons, so deal breaker.
That said. Just checked the local pick-a-part, they have 17 '97-'02 ford explorers, iron heads are $32 each. So im just going to throw a set of springs on em and touch up the valves. Is there anyway to see externally if they are 58cc or 61cc chambers? Also, being as im sure i cant find a set of 'P' headers for a '69 Fairlane, i wonder if im better off losing some compression with regular GT40s, vs. fighting the spark plug clearance with 'P' heads. Furthermore, how much would 64cc chambers drop compression vs. 58cc? (Ill look for a calculator for this, i think ive seen one before)

Between the GT40 and GT40P ive read that they give the same overall bump of 20-40hp bolt on, but as the P has a more efficient chamber and smaller exhaust valve, im assuming that it has the power band a little lower.