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Old 06-12-2003, 09:06 PM   #1 (permalink)
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460 losing power

i recently installed a rebuilt 460 in to my bronco. i ran great and had lots of power. then the needle and seat started messing up on it, so i installed a rebuilt carb of the same model. its a holley carb made for motorcraft. the carb is from a 87 ford with a 460. now i don't have nearly the power i had before. the truck runs great and every thing but it just dosent have the power i had before. what gives
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Old 06-13-2003, 08:37 AM   #2 (permalink)
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mmmmmmm. Might be that Ford emblem on the front

But for real, what did you have on there before for a carb? was it bigger, possibly giving more go juice to that power house?
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Old 06-13-2003, 09:53 AM   #3 (permalink)
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The carb is probably smaller than your previous if everything is functioning properly.

My Dad di the same thing on purpose to help his gas mileage.
He had a 750 CFM that would get it, but he replaced it with a 600 CFM to help on gas. It helped but you could really tell it was under carburated
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Old 06-13-2003, 09:56 AM   #4 (permalink)
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And even if you put on the same cfm carb, it could be jetted entirely differently, have a different power valve, etc. First make sure you have the correct cfm for your engine, then start experimenting with jets, mixture setting, etc. Holleys are the best imo, but you can't just bolt them on and expect maximum performance.
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Originally Posted by 94stepsideford View Post
Seth is scarier than you though. He looks like he would kill and eat a baby with his bare hands.
'73 F250, 533 on N2o, 35spln chromo Superior/CTM D60/D70, twinsticked 205, hydro-assist, f&r lockers, 46" Titan R1s. Videos: bad ass ford - YouTube Bad Ass Ford2 - YouTube
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Old 06-13-2003, 09:55 PM   #5 (permalink)
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the carb i replaced was the same model holley that is on my motor now. i checked the jets and the powervalve between the two carbs and they are the same ones. i even swapped the jets out of my old carb to see if it helped. i was thinkin maybe my secondaries are not opening all the way. how can i tell if they are opening all the way. they are vaccum secondaries and im told that there has to be a load on the motor for then to open.
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Old 06-13-2003, 10:23 PM   #6 (permalink)
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Well, if everthing else is equal, try putting a lighter spring on your secondaries and see if that was it. They do need load to open so I don't think you'll be able to check it in your garage, other than visually inspecting the linkage and making sure there isn't a tear or leak in the diaphram. Or you can do what I do and run a dominator and not worry about vacuum secondaries
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Seth is scarier than you though. He looks like he would kill and eat a baby with his bare hands.
'73 F250, 533 on N2o, 35spln chromo Superior/CTM D60/D70, twinsticked 205, hydro-assist, f&r lockers, 46" Titan R1s. Videos: bad ass ford - YouTube Bad Ass Ford2 - YouTube
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Old 06-15-2003, 05:23 PM   #7 (permalink)
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The carb may have been purposely made to produce lower performance AND lower emissions because of the year.
What was the year of the last carb?

Dave
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