Exhaust modifications

[alanbrown]

Having assembled and run my 250 arrow engine, with new exhaust pipes and sealing rings, I cannot achieve a gas tight seal. One of the barrels has adifferent thread depth for the threaded collar,approx 5mm different to the other side. I suspect that the collar is bottoming out on the thread rather than compressing the seal ring. Because this engine will eventually be used in a "race replica" and have fabricated expansion chambers starting at the barrel ports, I am considering machining off most of the exhaust port to give a shorter port, a different exit angle and also the chance to use a sleeved collar and springs to retain the pipe. I have seen a picture of a racer somewhere with this mod. Can anyone recall the picture, and possibly comment on my idea?
Thanks
Alan

[AndyEames]

I am sure Jess has got an iron barrel with the modification you mentioned Alan. If I remember ,its been bored for resleeving. We will be using springs on short, sleeved stubs on ours for the expansion boxes. Iron barrels on ours .

[Ivor Collins]

Hi Alan

Is this possibly the one you have seen before?

[alanbrown]

Yes, that’s the one! Thanks Alan