Okay guys I bought a 12A RB header, or at least what I thought was a 12A header. I got a manifold gasket and the header and gasket don't match. The exhaust ports on the gasket are about 7" from outer to outer and the header is about 7 1/8" from outer to outer. Can anyone identify this header?

 

The exhaust ports on a 13B will be about ~10mm further apart than the 12A.

A guy I know has a "Universal" header for his racecar. It's actually a RB 12A header, with the flange cut down the center. He done that to make it bolt up to the 13B he put in, to replace the 12A, but never welded it together. He was rather glad he hadn't welded it, when the 13B spit a carbon apex seal, and he had to use the 12A backup engine.

 

Oh, and the 12A gasket I have also measures 7" from outside to outside of the ports.
The critcal measurement is the mounting holes. 12A has a 4 3/4" center to center on the mounting studs, 13B is close to 5".

 

Yeah mounting holes don't match up either. You think I should cut the center or just try and trade for a 12A header?

 

That depends. If you got the header for dirt cheap, and don't mind a possible exhaust leak, you could cut it. Otherwise, I'd see if anyone wants to swap or buy the 13B header.
The example I used, is a racecar, so exhaust leaks aren't much of an issue, not that he has any that I am aware of....

 

Let me know what you paid for the header, i need a 13b header for part of an experiment so if i might trade you a brand new one for it.
PM me or email or call it doesnt matter

X7 Productions
1-616-890-8113

 

Anyone want to trade my 13B header for a 12A header?

 

I can't believe nobody has mentioned the super easy way to remember how to determine which engine a header fits. Of course you need to access to a metric tape measure or ruler.

12A stud spacing is 12cm
13B stud spacing is 13cm

Couldn't be simpler.

 

Never heard that one before Jeff, excellent.

 

Great tip, Jeff. Too bad I don't have a metric ruler.....

 

You don't have a metric ruler and you've worked on a metric car for how long? For shame.

Just joshing with you.