[dirty_d]

One of the previous owners of my car installed some shorty headers, from the separated flanges they look like MAC headers. I've found a set of gt40p heads for cheap, and I'm hoping these won't give me too much of a spark plug clearance problem. Maybe they even installed the gt40p headers in anticipation of a future head swap? Can anyone tell from these pictures if they are gt40p headers or if they will work for me?




http://postimage.org/image/2u5pku39g
http://postimage.org/image/2u5w6zh8k

[BULLET20XD]

If they are shorties they will need to be the Ford Motorsport (Racing) shorty for the p heads, otherwise id use a set of longtubes and just cut a plug socket to install the plugs. Maybe some other guys can add some advice.

[BULLET20XD]

I looked at the pics again, the sure way to tell if they are stock bent is look at number 5 and 6. If the tube is in front of where the plug goes and you cant get a socket on it to install the plugs, then no its a stock bent header.

[dirty_d]

I'm a little confused by that last post, so if they're gt40p specific headers I wont be able to get plugs 5 or 6 out on E7 heads? If that's what you mean then they're non-gt40p headers because I've changed all the plugs without issue. I'm not going to worry too much about the headers as it's still possible to change plugs just a pain in the ass. The heads come with the stock springs and rockers etc that were on the explorer. Should I get better springs or will the stock ones be ok, and if i do will the stock rockers be ok with the stronger springs? I'm assuming I'm also going to need to get a pushrod length checker and possibly new pushrods and shims. I already have a trickflow streetburner/track heat upper/lower, I'm not sure which one it was already on the car. These should bolt up to gt40ps without a problem right? I'm not trying to spend too much money here, just trying to get an idea of what I'm getting into before I get the heads.

[BULLET20XD]

They look to be stock header bends, as far as springs? I assume you have the GT40s not p's. You will need to upgrade the springs. I used The Ford Racing M-6513-A50 when i replaced them on my Explorer p-headed motor. A stock 6.25 pushrod will do with the heads you have. I used the stock pushrods in mine and the springs work good all the way to the limiter, thats with a B cam.Forgot to mention earlier, the GT40 heads have 3 vertical bars on the ends of the head, p's have 4.

[dirty_d]

The guy says they're p's off a 2000 explorer. Any guesstimate of rwhp numbers with the stock cam and trick flow upper/lower? Everything else is pretty much stock except for CAI, mac shorty headers and bbk h-pipe.

[BULLET20XD]

They would be p's if its a 2000! As for hp? id say in the 230-250 range. I would swap the cam. Also you can use some good quality roller rockers with that head such as Tricklfow, Crane, Ford Racing.

[dirty_d]

sticking with pedestal mount rockers? I was thinking about swapping the cam too, but I wanna do a lot of researching first before I can make any decision what one to use. I'd like to gain as much hp as I can without hurting the low end too much.

[OZ_872]

Im currently in the process of doing the same swap, put gt40p's from a mountaineer on, I had no idea about the spark plug angle thing but with my long tube bbk's it wasn't an issue. I also used the mountaineer springs and rockers with .030 shims. When I bought the car i was told it has a X303 cam. according to the lift on the cam and the spring pressure that we measured I should be ok. we're also putting an intake from an explorer on. Hopefully it will be up and running in the next week or 2 and I can let you know how it turned out