Has anyone else seen this problem?
When I got my headers there is a port missmatch by almost 1/4".
If you look at the FE heads the bolt hole above the exhaust port
is only a short distance above the port, but the bolt hole on the
bottom is half again or so away from the bottom of the head port.
Well the header flange is just the opposite with the large spacing on top. The gasket fits the head with the short spacing up and fits the header flange with the short spacing down.
This is telling me that they welded the pipes with the flange
set in the jig UPSIDE DOWN.
They at first said thats the way they all were and thats the way they have been making them, and the dealer said that there were 5 sets in the warehouse all with the wider spacing at the top.
Then they said that it was because I was using Edelbrock 6006 heads and that I would probably have to have special headers made up.
Well I checked in my trusty HPBooks "Rebulding Big Block Ford Engines" and there on page 45 is a picture of the exhaust ports
on 4 FE heads all with the long spacing at the bottom.
This missmatch would cause not only a loss of flow but a good chance of header leaks.
The latest word from Thorley is "we still think it is your heads,
but we are putting a stop on the jig so it can't happen again."

Does this make any sense to anyone out there? If it does will you go talk to them for me as I don't understand how they can prevent somthing from happening again that never happened in the first place. Will they prevent them from being made upside down or right side up?
I will let you all know how this turns out and if you have Thorley #203 check them and let me know if the large space is on top.

 

olddude,
I don't know anything about Doug Thorley headers or Edlebrock
heads but I do have set of 64 thunderbird heads(C4AE) and the distance from the center of the top stud to the top of the exhaust port is close to 3/4 of an inch.

 

OldPaul, I do hope you can send them back. Yes lots of us have had trouble with headers for FE fords. The problem is because Ford, for reasons noone seems to know, lowered the exhaust outlet in the FE series in 1966. Some folks refer to the lower exhaust port heads as 'drop-port heads'. The problem is that Ford didn't do it to all of them. So we have heads like my C5AE-F heads, used until '67 that have the high port, and heads like those on my truck, D2TE-AA that have the low port. The differance is 1/4 in, just like you have described, which is probably why Thorley wants to blame your heads. The big question is which exhaust port do the E-brock 6006 heads have ? I measured my medium riser heads and found they have the higher exhaust, center of top bolt hole to top of port- 3/4 in, floor to center of bottom bolt hole- 1.00 My truck heads are the opposite way. Measure yours and tell us what you have. You may have to use a differant brand of headers that understands the FE port options. DF

 

Thanks DF and Amule.
Yes the Edelbrock 6006 are the high port heads and if I remember correctly Edlebrock advertises them as "medium riser" heads.
Thorley would be correct in it's port placement for pickup truck use with the drop downs comming after "66" and the high ports remaining on the cars.
This leaves me with the option of sending them back or making them fit.
It seems that headers are made with a "bite" area around the ports which is actually the raised weld milled flat. With my old headers I port mached them by milling the flanges flat to the surface of the flange after having welded the seams on the outside of the flange where the primaries go into the flange.
This allows one to have a much greater gasket surface and use stock manifold gaskets. I used this setup for over a year
with these heads and cheap flowtech headers with no leaks.
Also this allowed my to use less than the 35ft/lbs torque on the bolts which is good for the aluminum heads. I used stainless steel bolts with 9/16 heads that were the right length to not bottom out but long enough to get a full bite, which the bolts that come with the Thorleys are not. I also used anti-sieze compound on the bolts so that they would not react with the aluminum of the heads. This worked good cause when I took off the headers the antisieze was still there brite shiney and still wet.
The other thing we have to do is elongate the bolt holes so the ports match. I can weld the holes closed and just relocate them but with the bite area gone and the thick 3/8" flange I don't think this is necessary.
Thanks again and I will post the results of this after the weekend.

Paul

 

I've heard about this problem before and was told that someone makes some 'tri-Y' headers that are a good match.

Just as a side note, my Hookers missed the port by about 1/8" and the gasket missed by even more. I cut the gasket bolt holes to make it fit and then elongated the header bolt holes and ground the flange where the tube is welded to get a proper match.

 

Well, I think it's time to wrap this up. I have deceided to use the headers and they are in the shop getting "modified" thus destroying my lifetime warranty.
I have not heard anything from Thorley since I E-mailed them proof in the form of an e-mail from Edelbrock that the port placement in the Edelbrock #6006 heads are the same as stock.
Thorley did a lousey job of reasearch on the FE series motors
and I give them a thumbs down. They are also very poor in responding to customer problems, offer practically no technical info on their product(send you to a salesman). And obviously don't stand behind their product.
Karljay, I looked into the try-wye and found that they are great for good midrange torque on 390 and smaller engines but I am into
a little bracket racing and needed to run 2000-6000 rpm power range.