question about GT-40 and GT-40p heads

[oldfox]

I have a 1986 5.0 engine and I may have the heads off of it soon I guess the 1986 were not very good heads so I have been checking on getting a different set. I'm told the the GT-40 is a lot better head and I can buy a set right out of the machine shop at a good price. Is it true that if I get the
gt-40-p heads
That I will need to change headers and some other stuff?
If I get the GT-40 heads will everything fit OK?
Also when the engine was rebuilt I'm not sure if they used flat top pistons or not.- But I do know they were replaced- If the engine has flat top pistons with no valve reliefs will there be a problem?

 

[danond]

You can use the original headers, sometimes, and usually involves some magic with respect to the plug boots, but a set of FRPP P headers isn't that expensive. Everything else bolts up.

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[oldfox]

You can use the original headers, sometimes, and usually involves some magic with respect to the plug boots, but a set of FRPP P headers isn't that expensive. Everything else bolts up.

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I was told that the GT-40 heads were a direct replacement.
sounds like I need to do some more checking before I tear it down
Thanks

 

[Vinnietbird]

There are a lot of horror stories about the "P" heads, and header issues. It's not that bad. The "P" heads a re actually the better head overall, and I have BBK unequal length shorty headers on mine. I just bought a set of Taylor plug wires with 90 degree plug boots. Plenty of room, no issues at all. Plus, because so many people are scared of the header issues (not really an issue at all), they can be found a LOT cheaper than the GT-40 heads. The P heads are also a direct replacement. Either way, GT-40 or GT40-P, you'll need to replace the valve springs with better pieces. the Explorer/Mountaineer springs are too soft for any performance application,, even the H.O cammed engines. I say get the "P" heads. I have them on the Sport right now, and they have been great. No issues, a direct bolt on,and as I stated, headers are not really an issue at all if you use unequal length headers.

 

[GotTrq]

I have P heads on my '86 engine also, I just had to put 90º boots on a couple plugs and they're cheap if you do them yourself. I got some headers from a local fox guy that worked with the P heads though, the stock headers had no chance... They were even too close to screw a plug in on the driver side, passenger side has a lot more room.

 

[captahab]

wont the pistons have to be notched to use GT40 or GT40P's ??

 

[oldfox]

wont the pistons have to be notched to use GT40 or GT40P's ??

The engine was rebuilt and I'm hoping that they used notched pistons
I'm going have a scope ran in the cylinder and see.

 

[MyHoFoSho]

Yeah i tried this swap on my e-6 headed motor and did not work the pistons did not have notchs cut in them and with the trick flow cam they hit maybe if no cam upgrade they might fit but it did not work out so well for me..And now my car sits in pieces waiting for me to get the funds together to finish the 347 i have to go in it...