289 with GT40P heads

Groover66 · Aug 6, 2019

Hey all, coming here to see if someone has a similar setup. I have a 66 coupe with a 289. I got a set of GT40P heads for next to nothing. I know the spark plug angle is an issue with headers. My question is, does anyone know for certain which headers will work with GT40p heads, t5 conversion with cable conversion, and stock power steering? Not looking to break the bank obviously. I've heard mac headers will work with gt40p heads but will they work with the stock power steering and a cable converter t5 swap?

Plllleeaaasseeee help

Jeremy

Groover66 · Aug 8, 2019

swooshdave · Aug 8, 2019

Groover66 said:
Bump

There’s not enough traffic on this forum to get immediate responses to difficult questions. You’d have to find someone with knowledge of your specific setup to get a definitive answer and that might be a challenge.

Olivethefet · Aug 8, 2019

A quick search shows a LOT of people have asked the question about "will these headers fit my GT40P heads". I'd suggest just doing a search and start reading. As for what header will work for the setup you are describing.... Thats pretty specific and unique. Somebody might stumble by that knows the answer, but it's going to take time. Is there a reason you want to use the GT40P heads other than they were cheap. Sounds like they might be more trouble then they are worth.

rustaddict · Aug 8, 2019

My shoot from the hip advice is to make sure you get a set of headers that fits the body and dimple around spark plugs as needed.

cwjr66 · Mar 23, 2020

Just answered another post like this. Hope it helps.
]
I tried this with the mac headers p/n TF6466 with p heads. Read many people said these would work.

I can say, at least my pair would not clear 3 plugs enough to even keep the wire boots off the pipes. Forget even trying to put a protector in them. That was trying the autolites and accel shorties. 2 could not even get a socket on them. Test fitted on engine stand not even in car which is a 66 stang,

To add to this, these headers would not even clear the back of the 289 block without the c4 bolted on. Too narrow at the collector

My solution was reproduction Hipo 289 manifold. These do fit. 1 plug is close but I ceramic coated them and got the highest heat boot protectors I could find. hoping this works car is still at body shop.

If these dont work going with aluminum heads. Good luck CW

cwjr66 · Mar 23, 2020

cwjr66 said:
Just answered another post like this. Hope it helps.
]
I tried this with the mac headers p/n TF6466 with p heads. Read many people said these would work.

I can say, at least my pair would not clear 3 plugs enough to even keep the wire boots off the pipes. Forget even trying to put a protector in them. That was trying the autolites and accel shorties. 2 could not even get a socket on them. Test fitted on engine stand not even in car which is a 66 stang,

To add to this, these headers would not even clear the back of the 289 block without the c4 bolted on. Too narrow at the collector

My solution was reproduction Hipo 289 manifold. These do fit. 1 plug is close but I ceramic coated them and got the highest heat boot protectors I could find. hoping this works car is still at body shop.

If these dont work going with aluminum heads. Good luck CW

I'll add thats the least of the problem. To make this work 1) measure new push rods a must. 2) New valve springs if using bigger cam than explorer, you will need to research Installed spring height and have to use shims, 3) Intake and exhaust have different spring retainer height. Any cam bigger than explorer you will float valves if pushed close to 4500. gt 40p has weak springs

Fireracer34 · Mar 25, 2020

Groover66 said:
Hey all, coming here to see if someone has a similar setup. I have a 66 coupe with a 289. I got a set of GT40P heads for next to nothing. I know the spark plug angle is an issue with headers. My question is, does anyone know for certain which headers will work with GT40p heads, t5 conversion with cable conversion, and stock power steering? Not looking to break the bank obviously. I've heard mac headers will work with gt40p heads but will they work with the stock power steering and a cable converter t5 swap?

Plllleeaaasseeee help

Jeremy

These work,
Sanderson Headers FF3GTS-SEC. See the pictures. The transmission is a AOD. I struggled so much I hope this helps.

cwjr66 · Mar 25, 2020

cool, when I hit the lottery, I get em. very very nice though.

289 with GT40P heads

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