I wanted to ask about the cfm vs engine size. My friend is running a 750 cfm Holley I believe on his 350 Chevy. This is in an 81 Firebird..not important though. I thought this was a horrendous amount of flow for such a small (relative) engine. I thought 750's were for 460's and such. Is the 750 too much? It's got a stock bottom end with more-than-likely stock-replacement pistons, stock heads, Edelbrock Performer RPM Intake, and a mild Crane cam.

On a more personal side note - would he have more hp then my 302? It's a stock 94 truck motor with bumped timing and exhaust done. I don't know..FI vs Carb...he's got the 48ci but I'm FI and have the exhaust.

 

Use this formula to calculate Required CFM:

Cubic inches X Max Rpm / 3456 = CFM required at that RPM. (given 100% volumetric efficiency)

In other words, he needs about 600 CFM at 6000 RPM, and wouldnt approach the capacity of his Carb until 7500 RPM, in summary, he is WAAAYYYY over-carbed unless he has some serious mods done to that motor.

 

750 was the stock size Q-jet for that car.

 

wow....thats a lot of carb, Hey jared, what are you doing up at this hour????

 

Almost all Qjet carbs were 750CFM, you adjsuted the amount the secondaries opened to regulate the CFM... I've seen them referred to as "infinite CFM carbs" on a few websites.. I'll post links if I can find them.