The problem is not the valving, but in the injection system, the 8V injection
system has only one injector, with a flow rate of 46 pounds per hour (PPH)
of fuel, this is fine for making 80 HP or even 90 HP, but not double the normal
HP this engine came with, at a minimum to double the HP you need to double
the fuel flow rate, so you need aprox 100-110 PPH of fuel.
Problem is there is no replacement injectors that can do this, at least none that
I have been able to find, I took my injector in to have it re-flowed but before I
was able to leave they stopped me and said they didn't have a fixture to even
test the flow with, so I went home with my injector in hand.
I considered dual TBIs to feed the beast, but in the end I stumbled on the
Megasquirt EFI system, so I bought and built that, which worked quite well
Most people would say just double the PSI of the fuel system, but that does
not work in reality like you think it would, if takes 4 times the pressure to
double the fuel flow, and at about 80 PSI the TBI injector cannot overcome
the pressure and will not open
Wild