1973 mustang gt40 heads

I have a 1973 Mustang with bone stock engine and I need to take the engine out and machine the heads because a valve seal is broken. I was thinking I may as well replace the head with something a little more performance.I saw a 2001 Explorer in the junkyard with a 5 liter engine. I also saw a Lincoln Mark 7(from what I remember) had a 5.0 ho looked late 80s. I'm also putting a 4 barrel carburetor and intake on it will there be anything I need to do to put the heads on or will they just bolt right on with stock pushrods, and bolts and stuff. the intake is in a wieand 7515.

Here is my "goto" thread for the GT40 heads.

http://www.allfordmustangs.com/forums/5-0l-tech/198384-gt40p-heads-351w.html

Sample you have a 302 right? Since all engines in 1973 were detuned and the 302 was the smallest V8 you might want to take some time and figure your long term goal with this car before you start putting your cash into that engine. There are a lot of parts and options for that engine for sure, but it will never perform like a 351C. just a thought from a guy who has spent a good amount of cash on a 72

I think the Explorer GT40 heads are better than the earlier E7TE 5.0 HO heads, but you might want to do some more digging. I think there were some later heads, GT40P perhaps? That are better than the GT40's, but their exhaust ports are in a different location so headers can have issues fitting...

Sample you have a 302 right? Since all engines in 1973 were detuned and the 302 was the smallest V8 you might want to take some time and figure your long term goal with this car before you start putting your cash into that engine. There are a lot of parts and options for that engine for sure, but it will never perform like a 351C. just a thought from a guy who has spent a good amount of cash on a 72

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Yes I'm sure I want to use this engine. Detuned yes but the part that is detuned is the larger head chamber creating a lower compression ratio. There are loads of parts for it. Some Foxbody parts will fit. Like the heads.

I could care less about the gt40 p being slightly better than gt40 heads. Ive heard some people machine the gt40 heads so the outperform the gt40 p

samplebridge,

You could stash your 1973 302. Adding rebuilt cylinder heads could cause the piston rings to fail due to the higher compression. You could find yourself a stock 1986 -1992 302/5.0 HO engine and do a good refresh.



Let us know what you do!

mustang7173

I had gt40p heads on a previous stang and they did perform well but the spark plug angle made it a huge pain to route the plug wires and change spark plugs. I would look for regular gt40's and pass on the "P" heads for the sake of fitment.

I would look for regular gt40's and pass on the "P" heads for the sake of fitment.

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The "P" heads are not different enough to make them worth the spark plug hassle, not even close.

The regular GT40's will bolt up to the block, intake and headers just fine.

They have stamped, non adjustable rockers that may or may not require changing pushrods on your engine. Some have production tolerances that are just a wee bit off, but chances are that stock length pushrods will work as is.

My hope would be that the Explorer heads are low mileage and do not require any valve/seat/guide work... just a drop on and go affair.

Around here, I find regular iron GT40 Explorer takeoff heads for $100-200 a set. I did see a freshly reworked pair on craigslist, still in plastic bags, for $200 that kept getting relisted. I somehow resisted the temptation to rescue them for my own collection since I have a set of the aluminum versions already.

At least you are thinking heads, which is where you will make most of your horsepower on a stockish 302. GT-40 heads would be an improvement and viable only if they can be had for cheap. The GT-40P heads are not worth the hassle dealing with the exhaust and spark plug interference. You might want to start adding up the costs. $100-$200 for a set of heads. Will definitely need better valve springs, valve job, maybe valve guides, clean, oil seals, a skim. Now you might have $500-$600 worth of machine work in them. You might be able to find a set of used Trick Flow Aluminum heads for $800-$900 that would be worlds better than the GT-40's. Probably to the tune of 50-60hp with the right supporting parts. It can start to snowball.

Grab the whole explorer long block. Change out the front cover, dampeners, and accessories to match what's in the car. (Minus a 50 oz/in balancer). It will be roller cam, hyper eutectic pistons, and a much better setup than the original '73 short block.