Makes sense....

 

That’s the part that got me. I‘ve poked around a P engine on a stand, so I understand the challenge of the different spark plug angle, and I could see this working. Thing is, if this did work, how could it not be common knowledge by now?

 

Do you put gaskets on either side of the plate?

 

Yes, that’s how I heard it described.

 

I'm skeptical. The problem with typical headers is that several of the tubes bend right at the flange backwards. With the typical SBF head the plugs are laid back. The P plugs are more perpendicular getting in the way of the tube itself. The plugs stock out farther as well. The tube really needs to come pretty straight out for about the first inch before turning. A good rule is if you can get a deep socket on the rear bolt of each tube, you have a pretty good shot

 

I'm skeptical. The problem with typical headers is that several of the tubes bend right at the flange backwards. With the typical SBF head the plugs are laid back. The P plugs are more perpendicular getting in the way of the tube itself. The plugs stock out farther as well. The tube really needs to come pretty straight out for about the first inch before turning. A good rule is if you can get a deep socket on the rear bolt of each tube, you have a pretty good shot

Yeah I am too, but with the right headers, I can kinda see it working.

might work on an engine stand but spacing the headers out away from the head will cause shock tower clearance problems

Well, I get that it’s tight, but I’m not sure the thickness of a flange would be enough to kill the deal.

 

might work on an engine stand but spacing the headers out away from the head will cause shock tower clearance problems

 

Has anyone tried it wit( the repro 2i9 hi PO manifolds or a set of TrI Ys?

 

TRI Y will need to be reworked on the drivers side front tubes . part of the reason I ended up with Edelbrock 5.0 heads . I've seen rebuilt TRI Y's made to work though

GT40P Tri-Y's?

Does anyone know where to get them, or anyone who is letting theirs go!? CCM is gone and I need a pair of headers like these!

www.corral.net

post 18 has some interesting pics of Explorer exhaust manifolds will gt40p heads fit on a 302

 

I can barely change the spark plugs with the jba gt40p headers designed for my mustang

 

Make a plywood template and experiment with various thicknesses.

 

Stock manifolds with a little grinding work. Personally I'm skeptical the K exhaust manifold flows any better. They both have the same 2" outlet. I did see a comparison on the same car on the same day on the same chassis dyno where stock, K code and try y headers were tested on a 2.25" system. The stock and K code manifolds made exactly the same power. The try y made something like 15 hp at the wheels.

 

I would say it might work. On SOME cars and SOME headers. I had a GT40P on the stand for a while and tried all of my collection of headers, short, long, some for Foxes even, no. Borrowed some mid-lengths and another set from friends. No chance of fitting. Then like I don't enough enough junky headers around I bought some unknown long tubes reputedly from a "289 Mustang". Fit straight on. I would grind a little bit of flange for spark plug clearance but other than that, right on. Just going by my memory of when I was fiddling with various headers I believe that some could be spaced out effectively and on some it would be a waste of time. No hard and fast rule.

 

Issues I see:

• I am not sure I have seen hex head header bolts that would be long enough.
• I doubt there is room in a 65-66 engine bay
• Fighting to slip one header gasket in can be a task, now two gaskets and a rigid spacer?
• Seems far more likely to leak

 

I am not sure I have seen hex head header bolts that would be long enough.

Seems like that should be a findable thing.

• I doubt there is room in a 65-66 engine bay

I'm sure it depends on the headers, but there would be with my Hedman Shorties.

• Fighting to slip one header gasket in can be a task, now two gaskets and a rigid spacer?

A pain, for sure, but maybe if you hold your tongue right.

• Seems far more likely to leak

Maybe, but for the price difference I'd be willing to give it a shot.

 

I can say definitely, no, stacking a 2nd flange will not work. I had GTP heads and tried Hooker, Headman and Flowtechs. The plug runs right into the tube on a few cylinders. You could dimple some to work, but I seem to remember the #1 and #4 cylinders had a hard interference. There are headers out there that will work with little to no issues. MAC and FPA are two that come to mind as well as the factory cast iron manifolds with some help.

 

Last time I fooled with something like that, I just put the plugs in first, then bolted on the manifolds.

 

Although costly, these headers are designed for the GT40P head in a classic mustang: JBA GT40P header Note that the #7 and #8 tubes turn up then down to get away from the brakes, steering box and the K-bar. There isn't much room on the driver's side in that area. This is something to consider when you fit headers... some might fit the heads but not fit a classic mustang.

 

Per this dyno test short tube headers performed no better than stock manifolds on a mild engine. https://www.hotrod.com/articles/ford-351w-dyno-test-shorty-versus-long-tube-headers/

 

Interesting. And lame, lol. I want those header dollars to count for something.

 

On my 70 engine bag, all the long tube and shorty headers bolt up and have plenty of spark plug clearance with Gt40p heads. The drivers side is the problem on cyclinder 7/8 . Even after Cutting and rewelding some tubes to clear the spark plugs.... the steering box was in the way.
The only known headers that fit the drivers side with ample clearance to get a sparkplug socket and a regualar 45* boot is the sanderson headers for gt40p. I got mines off summit FF3GTS-P $360. Definatly well worth the price as I did not have to mess with them at all.
You will have to remake the downpipe

 

On my 70 engine bag, all the long tube and shorty headers bolt up and have plenty of spark plug clearance with Gt40p heads. The drivers side is the problem on cyclinder 7/8 . Even after Cutting and rewelding some tubes to clear the spark plugs.... the steering box was in the way.
The only known headers that fit the drivers side with ample clearance to get a sparkplug socket and a regualar 45* boot is the sanderson headers for gt40p. I got mines off summit FF3GTS-P $360. Definatly well worth the price as I did not have to mess with them at all.
You will have to remake the downpipe

unfortunately those aren’t available any more. The more expensive.FF3GTS-SEC are available and are supposed to work well with P heads.

 

Has anyone milled down GT40 heads to get the smaller combustion chambers of the P,head without the plug issues?

 

There's more of a difference between them then combustion chamber size and plug angle.

 

I don't consider the P head to have a small combustion chamber. I think it is around 60cc. The combustion chamber size is definitely not what makes the P head so good. The spark plug location allows for a more complete and efficient burn. This in turn allows the compression ratio to be higher on a 302 with the GT40P heads than one with normal heads. Also there was a lot of work by Ford to make the runners move air really fast without large ports. Most tests I've seen show the flow to be around what a basic Edelbrock aluminum head gets.

david

 

P heads aren't quite that good. I had a stock set that was gasket matched and had them flowbenched. They were pretty close to what's listed in this chart. At .500, they flow 185 on the intake and 126 on the exhaust. Pretty decent for stock castings, but Performers flow 226/168 @ .500, quite a bit more than P heads.

 

The flow numbers I've seen for the P heads were compared to the Edelbrock E-street heads. Of course numbers can vary a lot from bench to bench. Anyways the P heads are definitely the best iron production heads for the Ford small block.

 

E-streets, yes, Performers no. E-streets are like aluminum versions of stock castings. They're not a big performance upgrade.

And yes, for low-buck upgrades, the P head is the best value out there, even if you have to do a spring upgrade.