[workinprogress]

are these good heads? will they give a noticible gain? its for my friends 84 5.0
GT40 Heads (P) fresh for machine shop

[JBIGBOOTSY]

The gain is 10-30hp depending on alot of varibles.

[Speedstang302]

i used them on my mustang before but ported and polished...they had the int/exh done and the bowls..was going to have 3-angle valve job done but sold them b4 i could do that...they worked along very well with my gt40 intake and f303 cam...was dyno'd before port and everything at 27x something rwhp and ran 12.86 that same day with slicks..i wish i could have redyno'd it or ran it again after port work and everything..but 347 is coming so im content!!!

[Darrell]

25+ horsepower is common. I think the price is steep. I'd rather buy a set and have thenm machined so I know what I have. Buying something that is claiming "freshly machined" isn't telling you much unless you are buying them from a reputable machine shop.

[Tony_90fox]

I'd search around more...you can find virgin Gt40/gt40P heads for $250 plus shipping. Possibly cheaper at a Pull-a-Part... then like darrell said, you can have your own shop do the work...

[notchabovechevy]

just remember that any old headers won't work most lt will and 40p spacific shorties but do you really want to spend that much?

[JBIGBOOTSY]

Originally Posted by Darrell 25+ horsepower is common. I think the price is steep. I'd rather buy a set and have thenm machined so I know what I have. Buying something that is claiming "freshly machined" isn't telling you much unless you are buying them from a reputable machine shop.

a GOOD SHOP WILL MARK THE HEADS SO YOU KNOW WHATS DONE.

[terribleonexx88]

how much better are the "p" heads then the norm gt40 and wat year was the p heads in the explorers. i wat thinkin of just gettin gt40s a do them over and i dont really want p specific headers, so if anyone has experience with both that work be cool. my motor is stock and could use better flowin heads in my price range.

[e3sean]

Originally Posted by terribleonexx88 how much better are the "p" heads then the norm gt40 and wat year was the p heads in the explorers. i wat thinkin of just gettin gt40s a do them over and i dont really want p specific headers, so if anyone has experience with both that work be cool. my motor is stock and could use better flowin heads in my price range.

i have the p heads now they just got a valve job done and a port/polished matched to the large felpro gaskets on a flow bench i should have them back soon also new duel springs put in. there a bunch of headers out there that will work with them.. what headers do u have now? i belive stock ones will work if that is what u have but the ones that uausally work fine are ones that come stright out from the exhaust a few inches before they turn down.
the p heads are better then the gt40 and they seem to be more plentiful and easier to find. as far as the years of explorer i think it was late 90's google it i am sure it will come up.

[Tony_90fox]

97 1/2 and up explorers, and moutaineers have gt40P heads...

[Darrell]

Originally Posted by notchabovechevy just remember that any old headers won't work most lt will and 40p spacific shorties but do you really want to spend that much?

There are alot of headers that work. MAC and BBK full length 1 5/8 headers work. Stock shorties work too.

[Darrell]

Originally Posted by terribleonexx88 how much better are the "p" heads then the norm gt40 and wat year was the p heads in the explorers. i wat thinkin of just gettin gt40s a do them over and i dont really want p specific headers, so if anyone has experience with both that work be cool. my motor is stock and could use better flowin heads in my price range.

GT40P heads have smaller chambers and better flowing exhaust ports than GT40 heads. The combustion chambers of GT40P heads are also more efficient than GT40 heads due to the relocated spark plug.

[Speedstang302]

so what shortys will work with p's?

[Darrell]

Originally Posted by Speedstang302 so what shortys will work with p's?

Stock. Other than that I don't know besides the P specific shorties. I don't buy aftermarket shorty headers. I'd rather spend my money on something that is going to net me a horsepower gain.

[JBIGBOOTSY]

Plug clearance varies from header to header. Most likley some heat sleves, and well routed plug wires are ways to work thru the header problem.

[Speedstang302]

no darrell with 3" lowering springs, having LT's doesnt really work for me..


i'd rather a set of shortys...

[Darrell]

Originally Posted by Speedstang302 no darrell with 3" lowering springs, having LT's doesnt really work for me.. i'd rather a set of shortys...

My car was lowered almost 5 inches in the front and long tube headers fit just fine. Buy some good ones. Even BBK long tube headers should work. I did the old cut off wheel trick on a set of stock springs and lowered the car 2 1/2 inches and BBK headers fit nicely. I can't say much for the alot of other headers out there. I've pretty much only used Kooks, Furo and BBK headers on my lowered cars. I know Bassani headers don't work so good when you get over 1 1/2 inches lower. I had some on my black notch when it still had a 347 in it. After I put the drop spindles in and roughed the ride height I lowered the car down and the headers had about 1/16 inch of clearance above the floor.

If you'd rather have shortys just use a stock set of Mustang headers.

[Speedstang302]

nah i'll pass on stock headers...i'd rather another set of gt40s...im just wondering cuz i can get them outta a junk yard for $50 for the set..but im building 347 this summer so i think i can hold off my pwr hungry lead foot for a little while longer..i'd either do bbk, hooker, hedmen or kooks..but most likely bbk..i wanna get most amount of pwr out that 347 so LT's are almost a must...damn all this talk is making me wanna do it now..but i'd put myself in $15k into debt real quick..so until schools over its gunna have to wait..

[Darrell]

Originally Posted by Speedstang302 nah i'll pass on stock headers...i'd rather another set of gt40s...im just wondering cuz i can get them outta a junk yard for $50 for the set..but im building 347 this summer so i think i can hold off my pwr hungry lead foot for a little while longer..i'd either do bbk, hooker, hedmen or kooks..but most likely bbk..i wanna get most amount of pwr out that 347 so LT's are almost a must...damn all this talk is making me wanna do it now..but i'd put myself in $15k into debt real quick..so until schools over its gunna have to wait..

Keeping stock headers is a good economical choice when you are on a budget and are stuck on staying with shorties. The horsepower gains of aftermarket shorties are so minimal that you won't even notice a difference at the track even with 1 5/8 inch primaries versus the stock 1 1/2 inch primaries. Just some tried and true FYI.

$50 is a good deal for GT40s. They are a bit too small for a 347 though. It will make good torque but it will be dead by 5000 rpm or sooner.

[e3sean]

what headers do u have?? they might work with the p heads my off brand shortys work just fine. as long as they go out a little before they turn down..