Passenger side is no problem, whatsoever.



Cylinders 1,2,3,4.

1

2

3

4


Now, what I don't like about the Scott Drake reproduction:  passenger side:

This should have never made it past quality control.  That is pretty deep. 

Last edited by Greg B (5/14/2025 3:22 PM)

Quick response update.   I sent Kentucky Mustang that picture of the manifold defect.  They immediately agreed that's no good and are sending me a replacement.    That is great customer service! 

Just think everyone should know that.

Nos681 wrote:

Thank you for posting pictures Greg.

Could you add a couple of  measurements to this thread for me?

With exhaust flanges on flat surface, what is the maximum distance to outer edge of “log” section and the “collector”?

Especially in are where shock towers would be located.

Just comparing to some late model manifolds in my possession.  Thanks!

Bullet, did you modify the manifolds Josh mentioned?

I do not remember details.

On the driver's side, it is 3.1 inches at its highest point at #5 It angles inward about a 1/4" inch at just at 2 3/4" at  6 and 7 and then slowly curves upward.  It is right at 4" at the tip top of the exhaust flange. 

Passenger: Is 3 1/4". at the bottom of #1.  It then, curves in slightly to 2 3/4" at 2 then starts a steep curve and is about 3 1/2" at number 3, 4 1/2" at #4 and the exhaust flange is 5 1/2".

This was measured with the manifolds on a flat surface with the ruler on the bottom side.   If one measured from the top, all of the ports are under 3" with the exception of the number 4 cylinder.
 

Last edited by Greg B (5/16/2025 1:13 PM)

Greg, thanks for sharing this information.
I really appreciate it.

Bullet, I thought you had said they were modified.
Mostly on side bumping into Falcon shock tower.

So, is there a great difference in the GT40P heads vs the GT40 heads besides the angle of the spark plug when installed? More or less advantageous to use the GT40P's. 
Seems a lot of extra hassle and work to find the correct headers that will work with the P's. Why not just get a set of GT40's where there are more options for headers?

Ron68 wrote:

So, is there a great difference in the GT40P heads vs the GT40 heads besides the angle of the spark plug when installed? More or less advantageous to use the GT40P's. 
Seems a lot of extra hassle and work to find the correct headers that will work with the P's. Why not just get a set of GT40's where there are more options for headers?

Well, for me, it's a cc chamber thing.   It is a 289.   Gt40 heads do have a bit larger chambers than the p heads do.   Both have some pretty wide manufacturing tolerances.   289 needs the smallest chambers you can get. 

I was considering putting the E7 heads that I have on there.   I was cruising the local marketplace, there is a set of D0OE-c heads on there, which are tempting.  Old school!   And there are several sets of 60s 289 heads, that need work to use.   He C at that point, might as well get a set of cheapie aluminium heads.   But that defeats the whole purpose of this.   

This car and engine was supposed to be my low buck mostly parts I had laying around thing.  The p heads are the best that I got. 

I never originally intended to buy new manifolds.  That said the hipo manifolds are for my convertible, not this car. 


 

Have ya considered mild porting the E7 heads and have it milled afterwards?
Have you tried F-series truck exhaust manifolds?

I still have E7 heads on the stock 5.0L.
Only modification is exhaust opened to match header gaskets.

I may not win races, but sure have fun driving it.

Last edited by Nos681 (5/18/2025 6:40 PM)