460 pulling power problems
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Joined: Sep 2002
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From: Philipsburg USA
460 pulling power problems
I have a 78 F250 Super Cab with a 460 & C6. I am having a problem with it losing power when the secondaries of the carb come in(holley vac. sec. 4bbl), especially when pulling a hill. Any help would greatly be appreciated.
New User
Joined: Sep 2002
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From: Curra Australia
460 pulling power problems
First, and easiest thing would be to check the float level on the rear float chamber. If that is low, adjust it and try again before altering jet or power valve size. If it's correct, look at the jet & power valve size. I am confident that someone on this site has the same combination and can tell you what size is best, if they know what else you're running. ie, headers, carb size, cam, etc.
Posting Legend
Joined: Sep 2001
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460 pulling power problems
You may want to check with the [link:www.ford-trucks.com/cgi-bin/dcforum/dcboard.cgi?az=list&forum=DCForumID76&conf=misc|Fu el Injection, Carburation and Fuel System] forum. The problem you describe may have been discussed there b4.
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Joined: Dec 2001
Posts: 22,436
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From: Louisville,Ky.
460 pulling power problems
Sounds like either a low float or crud that is blocking the metering plate holes. The Vac. secondary carbs do not have power valves or replacable jets in them. They have a metering plate. This plate is changable and they come in various sizes, but I don't think that that is your problem.
The secondary plated may be coming open too fast causing it to bog down from a lean condition(no accelerator pump in the rear). Has anyone changed the spring over the secondary diaphram?.
Try the float first, Remove the sight plug in the side of the rear fuel bowl. Gas level should be just below the bottom of the threads. Gas should come out if you rock the truck a little.
If the level is good, and you still have a problem, I would disassemble the carb and look for crud inside, then clean it(dipping it in carb cleaner overnight is the best way), blow thru all of the passages and reassemble with a rebuild kit.
The secondary plated may be coming open too fast causing it to bog down from a lean condition(no accelerator pump in the rear). Has anyone changed the spring over the secondary diaphram?.
Try the float first, Remove the sight plug in the side of the rear fuel bowl. Gas level should be just below the bottom of the threads. Gas should come out if you rock the truck a little.
If the level is good, and you still have a problem, I would disassemble the carb and look for crud inside, then clean it(dipping it in carb cleaner overnight is the best way), blow thru all of the passages and reassemble with a rebuild kit.
