[alien-e]

How many CFM's can a stock 240 engine take, and how much tolerance should I calculate into that number, since the engine has 120,000 miles on it and never been rebuilt?

 

[jerja]

The engine will not benefit from anything over 300 CFM. Depending on the carburetor design you can kill the bottom end power and throttle response by selecting one that is too large for the engine.

 

[alien-e]

I bought my 73' 240 with a Holly 4 barrel on it. I have a feeling that it has a much larger CFM. It has very little bottom end power and only shows strength when it's wide open. I'm getting rid of it in favor of a Carter, and may eventually go back to the stock SU's.

Thanks for your help jerja

alien-e

 

[jerja]

The SU's work real well on the street. Do to their constant velocity design they perform real good on the bottom and the top end.

 

[jeffp]

Carter makes a very good carb, but again you will have twice the carb you need. There is a calculation you can do to determine how much air the engine will suck at WOT and that is what you should shoot for. I dont remember the formula off the top of my head, but have it at home. mail me if you want and I will do the calculation for you.
I need to know the bore, and stroke, tell me what you have for the bore and the engine and I can calculate it for you.