Magna86

Ok I have ID'd my Holley carb. Its a 6120-3 which equals a 650 cfm double pump model 4165. I'm planning on rebuilding the carb as I can tell it just isn't right. As I read online that these carbs are not the best for street use maximizing efficiency and a Q-Jet would be better. The car is going to mostly a cruiser and would like to maximize the fuel mileage plus the engine doesn't seem to be built up very much since its running 350 heads/cast manifolds and the cam is not very lumpy.(455) What do you guys think? Also looking at the pulleys today I see they do not line up and the water pump is farther out than the crank. Is there a way to ID 455 and 350 pulleys so I can figure out which one may need switched? Also guessing thats why the PS pump pulley got a slight wobble.

copper128

That's NOT a carb to run if you're looking for fuel economy. The 6210 is a high-performance Q-Jet replacement usually intended for manual-trans cars or automatics with a high-stall converter and numerically-higher rear end gears.
For an economy-minded street application, you'd be far better off with a QuadraJet tuned for your combination.

PS pump pulleys are easily damaged. Yours might be bent, causing the wobble.

Rickman48

And the previous owner might have installed the wrong water pump - there's 3.

Magna86

Ok so the belt alignment issue could be the pump or the pulley? How do you tell which is the incorrect one? Any recomendations on which Q-Jet to get? (yr/model)

ah64pilot

IIRC the pulleys are all the same, it would be the water pump length that is making them misaligned. If the pulley is too far out (towards radiator) then you have a long neck water pump and you need a short neck water pump. If it is too far in (towards motor) then you have a short neck water pump and you need a long neck water pump. Hope this helps!

Steve

Magna86

That does help so a waterpump job is needing to happen great! lol Is the A/C waterpump the short neck or the long? (though I need the short one based on pulleys don't want to affect cooling) Ok what about fan shrouds? The A/C is toast but even it was good the belt wouldn't reach the pulley because the shroud is in the way? Which Q-Jet do you guys recommend?