Easy replacement for stock cylinder heads

Discussion in 'Fox 5.0 Mustang Tech' started by GrandmasterK, Aug 10, 2011.

  1. if you run the EGR with boost you need to run a one way valve in the vacuum line to it or youll blow the diaphragm out and have a big ass vacuum leak. been there have the T shirt. its easier just to get rid of it, since your emissions are going to go way up anyway when you blow the cats out of it. :)
  2. So why is the OP replacing the heads? I might have forgotten by page 3, but it seems like an important question. I hope you checked the block out first for compression. And I hope it was not for anything like a blown head gasket without a tear down first to confirm the new gasket has a good surface to seal to.

    I still wonder if a new set of iron heads is a better deal. Which is more important - cost and better heat/ blown gasket resistance, or 40 less lbs and running a little more compression? In short, if AFR, Dart, or TW offered iron at a good discount, I would be tempted to use them. Then spend the extra on Weight Watchers and blow all the weight savings with a small but custom woofer box.
  3. I bought a set of slightly used GT40x heads off eBay for a discount so I got a good price on them. Looking for the upper and lower intakes still.

    I'm in the process of tearing it down now. I had a shop look at the car and run some tests and they felt it was a head gasket issue but no, I haven't see / check everything myself yet. I'll be taking a good look at everything before I put it all back together. I plan to fix the car no matter what, so hopefully there isn't more broken that I have to spend money on o_O
  4. I am changing my tune on aluminum heads. An article in MM&FF swapped worked over GT40 heads on a car with other upgrades for Edelbrock heads and a cam. Iirc, it picked up 50 HP. That is a lot of go for an old 302.
  5. I personally would skip the gt40 stuff and jump to a used set of tfs twisted wedge heads and put decent rockers/springs in them and bolt your stock junk back on and roll it like that until you have the coin to toss a decent intake matched to how you drive the car and of course the supporting mods like tb,maf, injectors blah blah

    That sounds a little tough to believe there... got a link I wanna check out the article
  6. I believe it was in this months MMFF magazine.

  7. Thanks for the many suggestions everyone. I ended getting a set of GT40X heads and the GT40 intake off of eBay for a pretty good price (a little over $1000 total for both). The heads I ordered look like new, the intake looks like it could use some cleanup. Any tips on how to go about that?

    Is there anything else like rockers, pushrods, injectors, etc that I should also be upgrading at this time? Once I put the intake and heads on, I don't want to be taking them off again anytime soon.
  8. if the intake looks bad lightly scuff the whole thing, shoot it with degreaser to get all the gunk and grit off, prime and paint.
    not sure what rockers the gt40x use. If pedestal mount you should be fine with the stockers, 19lb injectors will be plenty for your combo, pushrods you always want to measure when changing heads or the cam. I want to say you will be fine with stock length but there may be ptv issues there.
  9. I recall an article a few years back where a set of AFR 185's made somewhere in the 90hp range more than a set of GT40X heads on the same engine. I don't remember the specifications of the engine, but it was certainly worked over.

    I personally don't have any real complaints about my GT40X's. The car runs well on the street and runs hard when I put my foot into it....but I'm certainly aware that if anything is holding me back with my combo, it's my heads.

  10. Is this the one your referring too? If so im fairly certain that car didn't have aluminum J,Y or X's.. they were just 3 bar GT40's hand ported and looking at the dyno graph Im not impressed much. I'd be tossing his Cobra intake back on with that combo if it were me. I mean it did make 40 to 50hp/1.5-5lbs as a whole over the previous heads and intake combo yes but gt40 heads and cobra intake are technically factory parts in my mind.

    #50 Boostedpimp, Aug 8, 2013
    Last edited: Aug 8, 2013
  11. heres the thing most people won't have the cash to even max out a set of gt40 heads..hell i use a set on my s/c on 14 psi...granted i did put larger valves and did my port work..alum. heads are nice options for wt and detonation at bay. but you better check you piston /valve clearance even with stock cam....you can buy a set of patriots used in the 500 range or edlebrocks for 650-700