Modifying Hooker 2312 headers to fit LSx in 944 engine bay

Instructions on how to modify the Hooker #2312 driver's side header. This modification is pretty straightforward, other than the part where you need to custom bend or fabricate a new primary pipe.

What you'll need:

- Hooker #2312 drivers side header (passenger header fits as is)
- a length of 1 5/8" .048" mild steel exhaust tube (unless you are using the stainless steel variant of the header)
- grinder with various sizes/shapes of grinding tips
- sawzall or hacksaw
- welder (or someone to do the welding)
- various clamps, rulers, protractors, files, etc.

1. This is what you start out with. Primary #1 is at the front of the motor (the leftmost one when looking at the header from the outside), and #7 is at the rear (rightmost).

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2. The exhaust port flange needs to be separated from the primaries. The primaries are welded to the exhaust flange on the inside of the ports. Using your grinder, remove the weld metal inside the ports until the flange comes off.

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3. Cut off #5 and #7 primary (the rearmost 2) above the weld line at the collector. Keep these pieces, as they are both re-used.

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4. You're going to be shifting the remaining section one port backwards on the flange, so #1 primary becomes #3, #3 primary becomes #5, etc. Using the original #7 primary, grind the lower end so that it fits between port #7 and the collector port closest to the block.

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5. This is where it gets a little tricky. The #1 primary will be a combination of the original #5 primary, and some custom bent/welded pipe. It is made up of 5 pieces, depending on how many are pre-bent. Here’s what it will look like when put together, and the dimensions to build it.

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6. For the header to fit properly, you'll need to grind off a "tab" on the block, right below exhaust port #7. Grind it back to the first step, then undercut it a little.

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7. Grind off the paint where the pieces will be welded. Be sure that the flange is in the correct orientation - the mounting holes are assymetrical. Tack weld the large primary assembly to the exhaust flange, then tack #7 on. Tack the #1 primary pieces together, but don't tack it to the flange or collector yet.

8. Test fit everything, then weld #3, 5 and 7 primaries to the exhaust flange and collector. Test fit again, and if everything looks good, tack and weld the long #1 primary.

Very nice! Thank for your time and effort that you put into this. Boy, I bet we know someone who is PISSED

Good write up, thanks.

Looks good. I will say this site has some good info.

Hmmm... I guess this is as good of a first post as any... maybe I can actually contribute something.

Has anyone tried these?

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The right (passenger) side looks like it may stick out more in the pic. The left (drivers) side layout, however, looks VERY close (although some tube positions are reversed) to the "modified" header.

I'm as enthusiastic as the next guy when it comes to making something that will work when there isn't a solution... but if these fit, that would be a great find. Especially since they are already less than the ones being modified here, before you even figure in time and cost to modify them.

Just a thought.

Brad

If that 1st long tube can be moved without too much hassle, then that would be a contender. It looks like the #3 has even more steering shaft clearance than the modded 2312 header. I'm considering unbolting mine and moving #3 about 1/2" closer up and nearer to the block to get more engine drop there...
Good find. It looks like the exit flange will fit without hitting firewall too.

Hmmm... I can't tell from the pics... so let me ask: Are you sure it would even need to be moved? Given that it sits on the inside and fairly "high" I was thinking it might possibly clear "as is."

BTW I just happened across this board a couple days ago... because I "inherited" my daughter's 944. (I bought it for her a couple years ago... but it's been of questionable reliability, so I want to make a "toy" out of it.) '86, decent body/chassis/interior but crappy paint... and a slushbox.

I was looking for a place to learn how hard this would be to do. Hmmm... may go out on a limb here and say the automatic stays FOR NOW. lol

That would be a home run if they fit, convince me to bite the bullet on this one and maybe ill be the guinea pig

The driver's side header looks like it might fit. It's the passenger one that I'm concerned about. That third primary looks like it comes out quite a bit, and might hit the strut tower.

Johnny Johnny wrote:The driver's side header looks like it might fit. It's the passenger one that I'm concerned about. That third primary looks like it comes out quite a bit, and might hit the strut tower.

Yup, I thought it looked a little on the wide side too. Unfortunately the only way to find out is to get a set and test them.

Think anything like that can be found at the junk yards? 50 bucks is a lot nicer than 150.

Simply genius! Nice post.

anyone interested in buying theses? cheap

i have a set of these, but i need a test fit, anyone be willing to do so for me? my ls block is gone and my kit is out of the car

Johny J,
Any suggestions on how to weld the pipes back into the collector?
How do you weld the inside portion of the pipes in the cluster?
Thanks

Tig weld the inside junctions

someone in need of these?

I could use a set, how much? email me at pzary3233 @ gmail.com

I'm looking for a picture of a driver's side Hooker Header that has been modified as published above.

Need to see how it looks from the top when installed on the engine. My welder wants me to confirm everything is in position before finishing the job.
Is the extended front tube parallel with the header flange?

look in my thread

Modenas,
PM sent,
Mike

Hey Mike, Look at my gallery, I made sure that the camera angles show the Modded 2313 and how #1 needs to tuck against the other primaries.

Thanks Rob,
Just what I need to show my welder.

subscribed, old thread

I wonder if these hooker header might fit better?

The flange is further back and close to the block.

hooker part number

8501-3HKR