HOME and how to join Forum Open Area General Scott topics Exhaust Re: Re: Exhaust

Steve Gibbon

Hi, I had been looking at the alloy manifold on EBay too. Does anyone know what the approximate exhaust port dimensions (measured on the outside of the block) are for long and short stroke engines ?

I have two blocks both of which I was told were 600’s . The external exhaust port openings measure :

block 1, 51mm wide x 21mm high with 69 central space between them (this block has approximately 75.4 mm bores and curretnly fitted to a ‘FZ’ numbered originally 498cc engine with approx 68mm stroke) – presumably this is a ‘short (68.25mm) stroke’ block ?

block 2, 49 -51mm wide x 24mm high with 70mm central space between them (This is a spare block – told it was a ‘DPY’ has a bore of approx 73.3 mm – presumably this is a ‘long (71.4mm) stroke’ block ?

So if I have a long and a short stroke block, the difference as far as the exhaust manifold is concerned is the height of the exhaust ports, which are ~ 21mm high on a short stroke block and 24mm on a long stroke block?