22 April 08
I'm spending a lot of time trying to get the hang of controlling the injection. I think it's going to be possible.
I show here the prototype cylinder head. It was machined from solid alum alloy. Four valves, with machined tracts. The cylinder size is 325cc and the inlet valves are 29mm od the exhaust 25mm.
The springs were from a Yamaha - and I'm just going to use the (smaller) inside one of the two springs per valve. (The Yammie motor revs to God-knows-what so the dual springs are very very stiff to stop bounce).
When the valve closes, if it slams against the seat, that's bad for the seat, so I think a
minor preload is OK. Which is what I've got. The inlet valves are from a VW 20-valve engine, exhausts from a Fiat of some sort. It's a case of needing
certain valve stem lengths to suit the angle of the tract + then spring length has to be fitted to suit.
Camshaft - I'll do that next time.
The inlet and exhaust tracts can be seen. The larger inlets (second foto) drop straight down from on top - the two holes on top are the where the inlet manifold will fit. The exhaust holes are at a 40 degree angle so are oval - their manifold would fit into these exit holes.
