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Discussion Starter #1
i think im having a problem. I just bought a 1996 f250 with a 460 in it. the engine has a 650 cfm holley carb. my problem is i seem to be getting about 3-5 miles per gallon just driving around town nice and easy. the engine is compleetly stock except for the holley carb and what i think may be an RV cam. Is this just normal gas milage? or is somthing wrong. the exhaust smells rich. what should i do? i have a brand new edlebrock 750 available to me and i actualy know how to work on those, would this be a good carb for this engine?
 

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Nope, that's not normal.

You will either need a proper competent Holley rebuild or trade out the carb- at least that would be my guess. Amazing a 460 can run at all dumping that much fuel through it. Is your air cleaner plugged up with ice and / or debris?

As far as it being all stock- I think it may have been futzed with considerably- I think that by that time it should have been fuel injected.
 

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It should be fuel injected. What I wonder is did it always run that way after the carb was put on. It could be an EMC problem if the setup was not rigged right. What about the fuel pump, did they put a regulator on it that could drop it to carb pressure or replace the factory pump? Put a pressure gauge on it.

That carb should be plenty, but not uncontrollably so.
 

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Discussion Starter #4
this truck has a motor that was rebuilt 20,000 ago by the previous owner. Im guesing it was converted from fuel injection. it seems to have good power it pulles hard on the hi way, but maybe not hard enough? it smells rich and has visable exhaust but its not smoking bad. would the edlebrock run well on this engine being 750 cfm? i may just swap that in. those things are awesome for daily drivers. what should i look for in the fuel pump to make sure its the right one? from what i hear the engine was built by a reputable builder. i just hope the cylenders havnt been washing down with gas and wearing badly
 

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Edelbrock

Lots of folks running 750 Edelbrock carbs on 460s but there might be a couple of issues - C6 transmissions require a kickdown lever (which can be added on later or your Edelbrock may already have one, but you need to be aware of them if you have a C6) and of course they don't fit too well on manifolds that had the spread bore motorcraft carb... which you don't.

The issue with the fuel pump is that fuel injected vehicles usually have an in-tank fuel pump that puts out too much pressure for a carbureted engine. If you have a fuel pump on the side of the timing cover, you might want to try unhooking the fuel line and finding out if there is fuel pressure coming from the tank (when the key is on) . There should not be anything more than gravitational leakage. If you have an electric fuel pump- you might still want to pick up a cheap pressure guage and check to see if the line pressure is excessive on its way to the carb- certainly you want less than about ten psi or so, five or seven might be reasonable.

Hope it turns out to be an easy fix.

Pretty common for 460s to have messed up chokes, too- make sure that it is opening all the way on any carb you use.
 

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Discussion Starter #6
wow i just re read my post and i just relized i said my truck was a 96 its actualy an 86 im sorry guys my mistake. does this clear any thing up?
 

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Could be as simple as a blown powervalve in the carb. Have you checked the float levels, timing and distributor mechanical & vacuum advance?
 

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As mentioned earlier... It probably has a blown power valve. You should not be able to see your exhaust.
The 750 Edelbrock (actually it's a Carter design) should work fine on your truck. I'd swap them out, rebuild the Holley while the Carter is on there, and then try the Holley again and decide which carb you prefer.
 

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I have a 87 F250 with a 750 Edelbrock carb & manifold, runs good but never gets more than 8 mpg city, 12 highway, the pump in the tank puts out about 6lb presure, I also run a holly pump and reg. up front and have a presure guage visable by the wipers, the back pump can't keep up by it self when truck is floored.
 

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First check the choke.Make sure it opens all the way when warmed up. Make sure the floats are set propperly(should just be to the bottom of the sight plug when running). If this all fails check the power valve. I personally dont care for the Edelbrock/Carter carbs but on a daily driver they are OK.
 

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Discussion Starter #12
what would be a good amount of timing for my engine? i'll try and lean out the carb a bit. my main concern is washing down the cylenders with gas and wearing my engine faster
 

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If you have a catalitic converter, you might wont to check your eng. vaccum, should pull @28in at idle, if vaccum falls of while it's idling your converter is stoped up. Just a suggestion.
 
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