fede

I'm buying a crate engine for my '75 and the manufacturer said their cylinder head exhaust port is 1-1/2 x 1-1/2 square. I need to buy some new headers but can't find anything that exactly matches that port on stainless steel.
I'm thinking of getting Hooker Competition Headers 2476-7HKR that have a primary of 1 3/4 but oval shaped. Will the increase in diameter make up for the port mismatch? Will they fit fine in my C3?
I need to get them from Summit Racing and they also have the same headers with a D shaped port but I think oval will be closer, right?

gkull

I have the hooker S/C 1 3/4 headers. Because of the tube size you need little tiny 5/16 nuts to clear the tubes. Header studs are the only way to easily install and remove headers

You need these items

https://www.summitracing.com/parts/fel-1404/overview/

https://www.summitracing.com/parts/a...1411/overview/



I put a dab of high temp red permatex on the 5/16th nuts to help ensure that they never back off

fede

Which headers did you get? The 2105-7HKR? I might get those but wondering if they will fit fine in the car with enough clearance to everything else.

BTW, those studs are really expensive!

gkull

Mine are 25 years old and have been recoated about 12 years ago. All my motors use studded exhausts. bolts tend to loosen with heat cycles. Early on i tried locking bolt ideas with limited success. Then i figured out that fully studded motors are the only way to build quality motors.. I like Spain and have spent quite a few times there.

https://www.summitracing.com/parts/h...model/corvette

Milder motors don't require 1 3/4 primary pipes. So you might just use 1 5/8th. in motors of let's say less than 400 hp

https://www.summitracing.com/parts/h...model/corvette

Kubs

Also, if you have a die grinder you can massage the flange of the header a little to line up with the ports better.

fede

I'm considering 1 5/8 too but want stainless steel headers, the engine is a 383 that should deliver 450hp+ and the exhaust system will be 2.5" with an X-pipe and Magnaflow mufflers.

gkull

I have these ceramic coated and like I said 25 years old and I have stainless steel 1 7/8th that I use on my 434 ci small block. Stainless discolors into blue and brown really fast. I have 3 inch exhaust with an H pipe and 3 1/2 inch in and out mufflers to keep the back pressure low

fede

For future reference...

I called the tech support from Hookers and JBA and ended up with these 3 options:
Doug's Headers D334
Hooker Super Competition Headers 2134-1HKR
JBA Headers Cat4ward Headers 1815S-1JS
(there was a 4th from Flowtech - Shortie 1 5/8 but can't remember the part no.)

The JBA's are stainless steel shorties, so shorties that look more like a manifold and 1 5/8. I wanted full-length.
The D334 and 2134 are very similar: full length, steel, ceramic coated, 1 3/4, 3" collector.
I ended up buying the D334 mostly because they have a 3/8" flange instead of 5/16 and also they were cheaper and included the collector reducer I needed (3" -> 2.5")

427Hotrod

For a 450 HP 383 I'd use 1-3/4" headers.

JIM