17 years ago.
Re: 350 cfm Holley on Clifford 4 barrel intake - 28/02/05 08:44 AM posted by Tony, "I found there was nothing to gain beyond 400 CFM."
I did a lot of additional tests on a modified 261 ,3/4 cam, stock 848 head, about 9-1 compression, Fenton headers with either a Clifford heated 4bbl intake or an Offenhauser heated dual carb intake. Using various 4bbl carbs from 390 to 600 cfm, Holley, Edelbrock and a Carter AFB and dual Rochester and dual Holley Weber on the Offenhauser intake, I found there was nothing to gain beyond 400 CFM. All the tests were done with a stopwatch on a measured back road stretch, using full throttle in second gear from 2500 to 4500 rpm, about 65 MPH in my 37 truck. All carbs were jetted for best acceleration which was pretty close to the stock jetting in all except for the Edelbrock 500 4bbl which had to have the primaries leaned out a few sizes. My findings are very similar to the engine CFM carb requirement charts offered by Holley. These are my opinions, on the way my engine was tuned, but I think they would be true for most similarly tuned 235/261 engines. [i][/i]
