22-11-2018, 01:24 PM
Carb size depends on state of engine tune, porting, valve size, cam profile, compression ratio, and to make it reliable the right crank/rods etc:
I ran a gas flowed 1 1/4" SU for years on my race engine but felt it was gasping for air on acceleration so upgraded to an H4 1 1/2" the change in acceleration is impressive and you don't need to rev it as much to get the same performance, it is also fitted with a blue spring and
gas flowed throttle spindle still with a 90thou jet and a std RLB needle.
Terry.