header length on cmb 45

[ww29]

can anyone tell me how long header should be for a cmb purple head 45.it has a mac 45 header and pipe.

it is in a phil thomas sport 40.

 

[John Knight]

Look at about 10" as a starting point for a sport 40. May need to be even longer. Riggers will be shorter.

 

[ww29]

john not pipe length.how long should the header be.just header

 

[John Knight]

Depends how long the pipe is. About 3" or so of stub is what I use to ensure a decent amount for the coupler. And the header is cheaper to replace than a pipe if you cut it too short. If the pipe fits over the header you may not need to cut much if any. If not, try to fit it so there is no gap between the header and pipe as it saves couplers and is more efficient.

 

[tnrcboatracer]

If it is the CMDI MAC 45 header and parabolic pipe, it should telescope. I telescope all my headers if possible. Haven't blown a coupler since I started doing it. The coupler is just a seal, no significant pressure, and absolutely no erosion of the ID from the hot exaust.

 

[ww29]

thanks for help guys