FYI GT40P head info

January 30, 2014, 12:48:12 PM

This comes up quite a bit on this forum so I'm doing a FYI post on GT40P heads and the EGR system.

All GT40/GT40P heads have internal EGR passages. I have run GT40Ps with the stock functioning EGR system no problem. The EGR port is the small square between the front two and rear two intake ports. All factory Ford GT40/GT40P heads have internal EGR passages. The GT40/GT40P heads used on the Explorer/Mountaineer don't have Thermactor passages (the holes on the rear of the head). Those have nothing to do with the EGR system. The Thermactor system injects fresh air into the exhaust, either in the heads or just before the catalytic converters depending on which solenoid is open, to warm up the exhaust to light off the catalytic converters. If you have no cats you don't even need to worry about the Thermactor system. The only problem with GT40Ps is header fitment. You'll need either a set from BBK or FRPP to get a decent fit with the GT40P plug angle.

The confusion on GT40/GT40P EGR passages usually comes from the intake manifolds used. From 96-mid 97 the Explorer's with GT40 heads used an internal EGR style manifold while the later Explorers with GT40P heads used a manifold with no internal EGR passages. This causes people to assume that GT40P heads have no internal EGR passage when in fact they do. Crazy thing is all Explorer/Mountaineer 5.0s use external EGR even though the 96-97 manifolds have internal EGR passages. Go figure. I've included two pictures. I've got a picture of a internal EGR Explorer GT40 intake and the intake where you will note the lack of an internal EGR passage. I also put up a picture of the intake on a GT40P head. Notice how it has the internal EGR port that all factory Ford heads do.

Not that I did a lot of research before I ran GT40P heads or anything. Now this is stuck in my head even though I no longer own a set of GT40Ps :hick:.

FYI GT40P head info

Reply #1 – January 30, 2014, 09:31:10 PM

Nice job!

FYI GT40P head info

Reply #2 – January 31, 2014, 01:22:19 AM

hummm,,, soaking it up..... may take a moment to delete all the stuff in my head sbftech said to controdict this.......... and i believe it just stuck. nice work.

FYI GT40P head info

Reply #3 – January 31, 2014, 10:09:13 PM

Just trying to help everyone out. I'm hoping that this thread comes up in a search when someone is looking for information on GT40P heads :).

I had the 6K mile GT40Ps I replaced with Edelbrock Performer heads sitting around my garage for 7 months before I sold them locally. I wish I had saved them because 2 weeks later I bought my Mark VII. It could be running around now with those heads and an internal EGR GT40 intake I have sitting around. With the stock HO cam it would have made close to 300hp, which would move the 3900lb Mark VII much better than the factory 225hp engine. Oh well. Live and learn.