question about GT-40 heads

oldfox · Sep 20, 2011

Hi ,, I'm looking thinking of picking up a set of GT-40 heads.
Not the GT-40p If I run the the GT-40 heads on my 91 5.0 will the head bolts be to small and require the adapter washers?

I'm told that with the GT-40p heads that there may be a problem with the way the plug angle and the header. Is this true?

xpkpremier · Sep 20, 2011

Dont let the plug angle scare you, most aftermarket headers will work. You will need to use 90 degree plug wires. As far as the head blots go, I think they are the same as E7 heads, someone please correct me if I am wrong. Good luck

myslo50 · Sep 20, 2011

if the gt40 heads are off a lightning 351 then you will need the washers to fill the space between the head bolt and the head.
if there off a 302 base motor then the bolts are the same.

just an fyi you will want to replace the head bolts with new ones. i for get the year when ford started using torque to yield bolts, and once they are removed you cant reuse them because the bolts get stretched .

oldfox · Sep 21, 2011

myslo50 said:
if the gt40 heads are off a lightning 351 then you will need the washers to fill the space between the head bolt and the head.
if there off a 302 base motor then the bolts are the same.

just an fyi you will want to replace the head bolts with new ones. i for get the year when ford started using torque to yield bolts, and once they are removed you cant reuse them because the bolts get stretched .

I'm doing a little boost I was going with 1133 fel pro MLS gaskets and
ARP studs. Sound about right?

myslo50 · Sep 21, 2011

anything arp is better then factory replacement

i have waiting is a set of gt40p heads for my fox. im researching for a set of headers to put on mine, i just have to decide if i want to go long tube or short tube. p heads flow better than the 40 irons but either way, either head flows better than the e7 head.

ReefBlueHatch · Sep 21, 2011

myslo50 said:
anything arp is better then factory replacement

i have waiting is a set of gt40p heads for my fox. im researching for a set of headers to put on mine, i just have to decide if i want to go long tube or short tube. p heads flow better than the 40 irons but either way, either head flows better than the e7 head.

I'm in the same boat as you. I read a good article that did a header comparison on a stock H/C/I car and it was long tube vs shorties. The shorties actually made more power and made a little more torque. Seeing how a GT40 top end flow a little better than stock, I'm guessing shorties might be better. I'm going with the FRPP shorties, mainly because of cost and fitment.

oldfox · Sep 21, 2011

I talked to the machine shop that has the heads and they are the F3ZE-AA heads
I think that's a 93 cobra head. Maybe someone drilled them out to fit a 351 or something?
I can get these heads for $369 totally redone and ready to go and free shipping
I don't think I can pass them up.

stykthyn · Sep 21, 2011

Lighting trucks ran gt40 heads. There are special bolts that will let you use them on a 302.

question about GT-40 heads

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