Firing order and headers

[Mike]

Looking from the rear of the collectors the firing order:

- 8 3 - 7 4 -
- 5 2 - 6 1 -

This seems to be what the originals had.

Looking at the firing order for the 289, the left collector fires in a circular fashion right collector, it seems like that 6 and 7 should trade places?

 

[Jac Mac]

Yes, I dont think the originals had taken the rotation of exh pulse into consideration. You might have to build two sets of headers, one set the write way and the other the right way!

 

[Mike]

Explains why the same headers work for either firing order. Just alternating pulses from each side to another achieves the desired scavenging affect apparently.

There are a few that tried a different approach. I suppose I'll stick with original design.

And another

 

[Jac Mac]

This the right way but not the original!