We switched carbs from a 1050 holley to a 850 bg , the holley had no power valve, the bg has a 6.5 power valve , The engine only makes around 6.5 to 7 inches of vacume @ 1100 idle , the bg guys say the carb is good for cams up to 260 @ .050 & that whats we have ,anyone take vac readings with a 260 @ .050 roller and come up with higher vac readings , we are 414 cid LA 12/1 comp W5 , we never took vac readings before cause the holley had no ports.

My solid roller cam is 260@.050 on the intake and 266@ .050 on the exhaust ground on a 108 LSA installed at 106 ILC. The motor has around 6.0 inches at 800 rpm idle in gear, 8 inches at 1000 rpm out of gear. I use a 4.5 power valve in the carb

I like to keep the power valves in the cars I drive and race They help keep the spark plugs clean by allowing you to run the motor leaner at part throttle