18 foot jetboat with jacuzzi yj with american turbine conversion. "A" impelller
463 olds w/ Ga heads  Ported quite a bit
180lbs compression.
comp cam 42-231-4, 230@ 50   installed straight up
single Holley 750 DP w/ mech secs, plug color is a nice tan.
Offy turbo thrust manifold. Intake manifold vacuum at idle is 11.5
MSD ignition and dist. +12 advance
Bassett over the transom water injected headers. No thermostat, engine temp is always 100F or less.
 
 
This thing runs great but, I can only get this motor to rev to 48-4900 rpm, sure its 61mph, but this thing should get to 6k rpm no? 
I'm getting parts to build up a holley 850, and give it some more cfm, anyone think i should try otherwise?

For the olds guys what carbs, impellars and rpms are you running?
 
thanks