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Does anyone know what size rochester (4 bbl) would've come on a 454 Mag/Bravo 1 in 1989 in a 23.5 Classic Carrera? I redid the motor for this guy and it seems slow out of the hole. I'm going to put my John Avery built Super Stock Carb on it this weekend to see if it picks up any but would like to know what size the original is. I'm sure it's never been rebuilt since it was new and I SUCK at Rochesters.
It has a quicksilver Mirage prop I don't remember the size but it's a three blade. Anyone have an idea on a good prop for this boat.
Thanks in advance.
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I'm no expert on carbs or Qjets, but I was under the impression that most of the Qjets were the same, around 800ish cfm, small primaries, big vacuum operated secondaries. Could be wrong though...
The Mirage is a good 3 blade prop and should give good top end numbers if it's the right size. If the boat is having slip problems out of the hole or blowout during sharp low speed turns, a 4 blade Bravo might help. The 4 blade can also settle high speed manners as well but you would likely lose a mph or two.
-brian
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"I'm no expert on carbs or Qjets, but I was under the impression that most of the Qjets were the same, around 800ish cfm, small primaries, big vacuum operated secondaries. Could be wrong though...
The Mirage is a good 3 blade prop and should give good top end numbers if it's the right size. If the boat is having slip problems out of the hole or blowout during sharp low speed turns, a 4 blade Bravo might help. The 4 blade can also settle high speed manners as well but you would likely lose a mph or two."
Thanks DH. That's what I was thinking around 800. But it just seems to not have enough out of the hole. I didn't get a chance to put another carb on it this weekend so I'll have to do it in a couple of weeks when I get back into town and see if I can get it any better.
As for the prop, it doesn't feel as though it's slipping and I didn't really get a chance to check the low speed turns. One thing I neglected to say before though is that the edges of the prop are pretty hammered, he touched a rock at Mead last year so I'm pretty sure it's lost some of the punch. He doesn't really care if he loses some on top he really just wants it to come out of the hole better. Mainly to pull his but out of the water on a single ski. O well, I'll play w/ the carb when I get back and maybe I can find someone w/ a prop to try and see what kind of difference that will make.
Do you know how to check and see what gear ratio is in the outdrive?
Thanks again! and sorry for the long post
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Some Q-Jets were 800cfm.....Most were 750cfm. You can make up to 475hp with a Q-Jet. Don't sell them short. Good carb for rivers and small lakes (short bursts of speed). If your running wide open for minutes at a time (offshore or big lake), go with a Holley square bore vac. sec....Mike.
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secondaries are spring loaded on,left side of carb. try adjusting opening rate and the response will get better. takes an allen wrench and screwdriver, go a little at a time about a quarter turn at a time. it should be a smooth transition, eek! not a momentary bog then scream. jawdrop most were 750 cfm some big blocks were 800's
