Have I installed the wrong Headers?

[jim7485]

66 Mustang with FRPP 302 crate motor w/GT 40 aluminum heads. We installed Hedman shorty headers, part no: 88400. The bolt pattern is fine, but there seems to be a fair amount of overlap, enough that I think flow may be restriced. The engine dude (more of a body man) told me it was normal, but I'm concerned. The car runs fine, but seems to lack power. Wondering if these headers are restrictive due to the overlap. They are correct for a 66-73 302. Question is: are they correct for GT 40 heads? I'm considering a switch to FMS-M-9430-P51 which I know are correct. Any thoughts? http://store.summitracing.com/egnsearch.asp?Ntk=KeywordSearch&DDS=1&N=+115&searchinresults=false&Ntt=FMS%2DM%2D9430%2DP51

Thanks
jim

 

[brianj5600]

I would contact Hedman.

 

[88dragtop]

I assume by overlap you mean the exhaust port on the header flange is smaller than the port on the heads? Even so I wouldn't think it would be as bad as a manifold. Hard to say it's losing power with the butt meter, dyno or 1/4 times would give you a better idea. Those FMS are late model headers and won't fit the early engine bay.

 

[truck90278]

We're running the Hedman Elite with no problems. We initially had the GT 40 Aluminum heads and switched to Edelbrock Performer heads - no problems either way - no lack of power

 

[BullittStangV8]

Is it casting flash that could be ground down? Or simply the ports dont match up with eachother? (meaing part of the head port is covered, and the header tube extends part the port in the head)

 

[jim7485]

More info....

A bit of clarification: The bolt pattern is perfect but the header flange holes do not match the ports. They are roughly the same size, but offset somewhat, perhaps 1/3 of each port is covered by the flange. Can I get some confirmation on an additional issue? Will the FMS-M-9430-P51 headers (which I know are correct for the GT 40 heads) fit between the shock towers?

Thanks
jim

 

[The Dan]

Is the flange covering the exhaust port from the bottom, or sides? You may have headers desiged for heads with raised exhaust ports???

 

[jim7485]

Now that's a great question. As I recall, the overlap was on the sides. If anyone else is using the crate motor with GT40 heads, which shorty headers are you using?

Thanks
jim

 

[jim7485]

The correct answer

Here's the correct answer right from Hedman tech: Thank you for using Hedman Products. Part# 88400 is designed for a stock application. These hedders will choke the motor. So they will come off. I'll measure the clearance this weekend to see if the FMS hedders will fit between the shock towers. Obviously some cutting/welding on the H pipe will be in order too.

Thanks
jim

 

[The Dan]

Glad you got it figured out. Headers always seem to be a problem for people, myself included. Sometimes wonder if they're worth the problems....ya, I guess they are

Good luck.