Ive been reading thru the forums that some of these guys have replaced stock heads with the gt40s out of the cobra mustangs of the same years. besides bolting on the new heads and pieces what other tasks are included? as in machining any parts, drilling any holes, etc. i found a set that i want to put on but i fairly novice mechanic with a few expert friends tho.

 

"3-line" GT-40s are a bolt-on with no issues whatsoever

So are "4-line" GT-40Ps (from 5.0 Explorers) except that you may have some issues changing plugs with some headers and possibly with the stock F150 manifolds.

To get the most out of either heads, you need to improve the exhaust system with shorty headers, a high flow cat and a cat-back and either swap in a bigger cam or at least change to 1.7:1 rockers.

If you add a cam you may need to upgrade the fuel delivery system to take full advantage of it which in turn may require you to upgrade the intake manifold and T/B to supply enough air

 

Awesome post thanks for the info!

 

alright so a few more questions... i have a '92 and the set i found fit a '93-95 are there complications with that? if so i can definitely keep lookings. they are listen as cast iron and not aluminum? good bad?? and probably the worst question, how do you know if they are 3 line? also too ive ran across a few sites listing something about e7's??? what do you know about them? even more so, here is a little reading if you dont mind taking a look at this site. this raised a few more questions.... these are all mods done on 5.0l mustangs.

http://forums.mustangworks.com/f8/gt40-vs-gt40p-38436/

 

The original GT-40 heads are iron. Ford later used the GT-40 designation for just about every streetable aftermarket performance head they built, including a lot of aluminum ones. AFAIK no aluminum GT-40 heads made it into any production cars, they were aftermarket only. Aluminum saves a bunch of weight which is more of a concern in a Mustang than in a truck and allows you to run a slightly higher compression ratio. Most of the aluminum heads flow a bit better but that's a function of the design, not the material

GT-40 heads have a small raised pad on the end of the head which has 3 lines cast into it. The GT-40P heads have 4 lines in the same spot. E7s are stock 5.0 HO heads.

 

Man, you got the answers to everything. ok one last question hopefully... how much time should i set aside to put these guys on once i have every part with me?

 

Time required depends on skill and experience. For most people it's a weekend job. For some it's a lot less for others it's a lot more.

BTW the GT-40 heads also fit the 351 block. This means that they have holes for 1/2" bolts rather than the 7/16" used on the 302. You have to use hardened 7/16" washers when putting GT-40s on a 302. Ford used to offer a bolt kit with trick washer headed bolts. The part number was M-6065-B289. Two kits required to do two heads. I have no idea if it's still available.

 

k i have this horrible habit of reading... now i'm finding that it is a good idea to upgrade fuel injectors as well. do stock work fine or should i find a new set and if so what kind and with how much pressure?

 

Larger injectors add exactly zero HP unless the engine is using enough air to require them. Use them in an application for which they are oversized and all you get are emissions and drivability problems.

The stock injectors are 19#. They are adequate for somewhere around 275 HP. The GT-40 heads alone are only worth something on the order of 30 HP so you have a long way to go until you need fuel system upgrades. Re-read post #2 above

 

will this bolt kit do?

http://www.summitracing.com/parts.aspx?sku=ARP-254-4405

and how about these rockers? how do i know what bolt size i use for them (3/8th is what im thinking)? pedestal or stud mount?

here are the ones im looking at.

http://www.summitracing.com/parts/FM...1/?image=large

 

That's a stud kit, not a bolt kit. And yes it says it is the right one for a 302 with GT-40 heads but I'd check with ARP just to make sure. Summit's parts sorter leaves something to be desired on occasion.

Those rockers are 1.7:1 rather than the stock 1.6. They'll give you about 5-10 HP when used with a stock cam but there are a very limited number of aftermarket cams which will work with them. If you're going to stick with the stock cam, they're a good choice; if you're going to go with an aftermarket cam, not so much.

 

alrighty, i accidently copied the wrong address on those.

http://www.summitracing.com/parts/ARP-154-3605/

i checked the ARP website and there discription says something a little different. "302 wth 351 windsor heads. 1/2"-7/16" insert washers with 7/16" bolts"

and ya i only plan to use the stock cam with these for now. im about to pick a set up that have less than 60k on them. full assembly. should i take them to get cleaned up or just bolt them on? stock pushrods work too?

oh and read this if you are bored

http://www.carcraft.com/techarticles...dup/index.html

 

"351 Windsor Heads" includes GT-40 heads.

As to freshening the heads, get a 3-angle valve job and replace the springs.

 

im glad i found this thread. my buddy is gonna give me his gt 40 heads to go on my 302. is it worth it to get the ported, and polished.

 

GT-40s are pretty good out of the box but a proper port and polish will always improve flow. The problem with any porting job, especially on a truck engine, is that if you overdo it and the ports become too large,you make big HP numbers at high revs but kill your flow velocity and lose performance at mid to low range which is where you need it with a 4500 lb. truck.

If you're paying to have the port job done, make very sure the shop knows what the heads are going on, what camshaft you have and where in the RPM range you want your performance peak. If you plan on doing it yourself, then go very, very easy on the metal removal. It's far better to leave a little extra in place than to remove a little too much.

If they were my GT-40 heads, I think I'd either leave them alone or go for a mild rework: polish, deburr and CC the chambers, clean up the valve guide bosses, only if necessary blend the bowls to the valve seats, clean up any obvious casting dross but otherwise leave the port areas alone. I might check the port alignments with the intake and exhaust manifolds and if it was off by a bunch do a port match (NOT gasket match) to them. For sure a get three-angle valve job done with back-cut intakes.