I know there are a ton of threads about "headers" and of course tons of tech related articles as well. Most of those threads or articles touch base on how certain aftermarket headers will or will not work with the 5.0 or 5.8 engine in a Bronco (or F-Series trucks). We all know there are the Summit Racing "cheapy" headers that do work, but require Y-pipe mods or tweaks... then there are the BBK, MAC, JBA, Gibson headers and so forth - but again, they all are addressed most of the time to the standard E7 5.0 or 5.8 heads.
I blew up the original 5.0 in my 94 Bronco last December and have finally gotten around to working on the rebuild. The old engine was trashed and there was no possible way it could be rebuilt at all (another thread exists on that).
So, I had purchased a complete Explorer 5.0 long block to use as my base rebuild, because of the fact that it's a "GT40" engine. The engine I chose is actually a GT40P engine, which means it has the infamous GT40P heads on it. If those of you out there know Mustangs or 5.0's in general, you all know that the GT40P heads require different or specific "GT40P" headers.
Now let me note for the record before I go on further - I read MANY threads on MANY different forums both F-Series trucks, Broncos & Mustangs - and many have stated that the Ford stock tubular 5.0 headers would work, many have stated the standard BBK headers would work and so forth.
I can attest by actually TRYING out the following headers on a GT40P headed engine that these headers WILL NOT WORK AT ALL, NO WAY, NO HOW:
1986-1995 5.0 stock tubular Mustang headers
stock Bronco 5.0 cast iron exhaust manifolds
1986-1995 5.0 BBK unequal length shorty headers
1986-1995 5.0 Mustang Ford Racing shorty headers
The reason those headers will NOT work or fit properly is because there is MAJOR interference with the plugs on the driver's side GT40P head. There is no way in hell to make the above headers work properly at all - period.
Now - back to the GT40P heads. I searched high and low for GT40P specific headers. True, some exist, but for the most part, 99% of the GT40P specific headers that DO exist are for the Mustangs. The problem with the GT40P Mustang headers is the ball & socket flange is skewed & designed for a Mustang and in order to make them work in a Bronco - you NEED to have a custom Y-pipe designed in order to properly mate to a Mustang GT40P header. So, my only other option I was thinking that I had would be I'd have to sell the GT40P heads and get another set of heads so that I could use a nice set of aftermarket Bronco shorty headers.
I continued to search and actually went to Ford Racing's web site. There on the Ford Racing web site, I saw the following headers - Ford Racing Part # M-9430-T50. These were specific F-Series headers for the 5.0 engine. According to all I have read online, these are a direct fit header and will mate up to the factory Y-pipe on all 1990-1995 F-Series trucks, E-Series Vans and also Broncos without any issues. There was also a side note that stated: "fits all production and GT40 heads".
Ford Racing link:
So, I took a chance, called and ordered a set from Summit Racing (Summit Racing Part # FMS-M-9430-T50 - $295.95). The headers arrived today and it was "test" time to see if these headers would indeed fit onto GT40P heads. The headers come with header bolts, studs, nuts & nice gaskets too.
Summit Racing link:
THESE HEADERS FIT the GT40P heads AND MOUNT UP GREAT!
The Ford Racing M-9430-T50 F-Series stainless steel headers bolt right up to the GT40P heads
with enough spark plug clearance that allows the removal and installation of the factory spec plugs. The trick to removing only a couple of plugs if trying to use a standard socket for spark plugs, is to insert the plug socket onto the spark plug and then use an open end or boxed end wrench to turn the plug socket (instead of using a ratchet). This worked perfectly and I tried the method by removing all plugs and reinstalling all of them - no issues with plug clearances.
There is also a company now that makes "short" spark plug sockets for tight fitting areas when removing or installing plugs (which would also come in handy for a variety of different header setups):
Product: Tight fit spark plug sockets
Manufactured by: Powerhouse Products (www.powerhouseproducts.com
There was only 1 single issue with the set of Ford Racing headers I received. The passenger side header primary tube for the #3 exhaust port was not properly angled for spark plug clearance. Put it this way, I could not even get a spark plug boot onto the plug! This was hopefully & merely a manufacturing "oops". To remedy the problem, the tube was heated up with a torch and a ball peen hammer was used to dimple that section of tubing down enough so that the spark plug could be removed/installed and so that a plug boot would fit properly. This was the ONLY issue I came across with the set I received and like I said, I see this as being a flaw in the inspection/tolerance/manufacturing process that missed the problem before these were boxed.
All in all these Ford Racing headers are very nice and of great quality. They fit nice onto the GT40P heads and appear to have the correct ball & socket flange angles to mate with the factory Bronco Y-pipe.
So - in summary, if you are looking to install a GT40P engine and keep the GT40P heads - the above Ford Racing headers will work!
I have pics, just don't have them processed yet. I will be getting the "new" engine into the truck in the next upcoming weeks, so I'll try and take more pics of it as it sits in the engine bay.