You are correct Steve, but I am not going down that road. Increasing compression with old Aluminium is asking for trouble, it age hardens, which means stud pulling issues. Heat treating would be essential.
I’ve been focusing on the burn. Swirl chamber fill is rather cool once you get a bead on it. Definitely a softer approach than squeezing crap out the fuel charge and needing higher octane fuel. I can’t begin to tell you about the imaging going on in my head mapping vortexes being squashed into donuts then flattened into this multi pressure drum cymbal shaped rotating disk, that’s then ignited.
My dad worked as an industrial chemist in the explosives factory in Melbournes west. He mentioned the “bee hive charge”. To direct your blast of the explosive, shape it to a rough cone, flattened the bottom fat bit and slice a cone in it. The size and shape of the inner cone directs the main pressure wave so you can punch nice round holes in things, like steel plate, trees and holes in the ground (they were playing quite regularly in the name of R&D apparently). Anyway the point being nice even push by the burn on the surface of the piston. The high comp piston dome runs well with the beauty of the burn, the valve pockets do not. Near as I can figure there’s a bit of zero sum game going on there.
Cams are standard late model SS cams, I have the figures in a manual somewhere, nothing special there, just dialled them in as accurately as I deemed reasonable using the centerline at the point of maximum lift. Read degree at 0.04 before needle stop, then 0.04 after needle stop. Divide by 2, near a god damn enough. Difficult to get much closer as the ramps start and finish about there. Anything closer, controlling rotation is a wee bit painful as well.
You could film the needle on the dial gage, slow it down. Time the 0.04 to stop difference and that would give you exactly where max lift is, but there in no point. Be like 0.01/2 out on a valve shim and it’s all out the window where the exact centre is.
102 is pretty much on the money for emolas, they are top end revy for HP. Excellent in a 750 l believe.
I run 107 on the ST cams in the 888, seems to handle up to 12500 rather nicely. Something I read about 110-112 on some insanely reving thing a while back. Crazy stuff.
I think what’s important also is symmetry. Closing front and rear tolerances so both doing the same thing is fairly important in the power chase. Free power to be had by symmetry. Go wonky, get vibration, generate heat and lose power. Simple.
