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LS Engine Header Modifications

Page history last edited by Greg 14 years, 2 months ago



Street & Performance Header Modifications - ['55-'57 Chevy LS1]


Modifying The Street & Performance '55 - '57 Chevy LS1 Conversion headers


The Street & Performance '55 - '57 Chevy LS1 Conversion headers may be modified for the 944 V8 Conversion. Only

the driver's side header needs modification. The passenger side fits with minimal trimming of the 944 crossmember

for collector clearance. The S&P headers are available in 1.625" primary (LS1) and 1.75" primary (LS2, 3, 6 and 7) tube,

2.5" and 3.0" collector sizes respectively, and may be ordered raw or HPC coated. V-Band collectors and clamps are

also available.


Driver's side primary tubes must be reconfigured for clearance of the 944 steering shaft. The shaft will pass between

primaries 1 and 3 after modification, and the end result mimics the classic Tri-Y design. An alternative modification is

in progress that allows the steering shaft to pass through primary tubes 3 and 5.



LS Header Modifications - Hooker #2312


Modifying the Hooker 2312 LS Header to fit it the 944 engine bay, and clear the steering shaft


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).



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.



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.



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.



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.



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, and then undercut it a little.



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 asymmetrical. Tack weld the large primary assembly to the exhaust flange, then tack #7

    on. Tack the #1 primary pieces together, but don't tack them 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.





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