My 59 Ranchero has a stock 71 351w with an Edelbrock 351w Performer intake. I had just pulled a great running 390 Holley carburetor from another engine and put it on the car. Vaccum at idle is a steady 21 at 650 rpm, no needle jumping at all. It reves great in park. It seems like it's not getting enough fuel not only off the line but through the rpm range up to 4k. It seems like it's missing or starving for fuel, but no Vaccum indicators of a miss. I understand that for top end I should be using a larger carb, that's not the intention of this engine. It's a cruiser. Any input is much appreciated
42merc is on target. For a cruiser, you've got the right manifold (the Performer, not the Performer RPM) and stock heads. 600 to 650 is your sweet spot. Going double pumper and 700-750 is more carb than you need for your purpose. You're in South Florida so type of choke probably doesn't matter much. Sounds from the vacuum gauge you have a smooth runner. You probably started setting timing around 10 degrees initial advance and fine-tuned from there, didn't you? Get yourself a little more carb and you're on your way.
A small carb will be great "off the line". Checking one of the online carb size calculators, a 351 engine at 2000 rpm needs, um, 172 cfm. At 3000 rpm it needs 258 cfm. At 4500 rpm we are running short of carb, as it needs 388 cfm. It is often argued that these cfm calculators are not really accurate, but even if it were, say, 25% under rating, you certainly won't be starving for air flow up to 3000 rpm with that small carburetor. So yes, the carb is too small for higher rpms, but it isn't the reason you have poor performance off idle to say 4000 rpm. You might also be better off with the stock 4V iron intake with a "cruiser".
@Beanscoot is correct. What I believe is going on is that the runner size in the intake is too large with that carb, and the velocity is dropping off past the throttle plates causing the fuel to drop out of suspension. I had a set of large runner heads with 2.02 valves on my SBF in my 53 and had the same issues. Went back to OEM heads.
The Jalopy Journal
