Bad Performance 460
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Joined: Mar 2001
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From: Fremont, NE
Bad Performance 460
This 460 in my 78 Bronco is a 75 Truck Block with a mild cam.
It has 15,000 miles on it and was rebuilt very thoroughly.
I cant get it to run right to save my life. I dont know what im doing is probably the problem. It has a 600cfm (I think) Edelbrock with electric choke. (Does it say on carb what size it is?)
Problems:
Hesitates constantly (from a stop light, hitting the gas at 35 MPH, col, warm (worse when its warm, not bad when its on high idle cold))
Deasels when you shut it off, sometime will do it even if its still in drive. Almost always when in nuetral.
Popping sound (From carb?) when it hesitates a lot.
RUns great once you get past maybe 1100 or 1200 rpm, fast truck.
What could be causing this? Timing or do i need a better carb, one guy suggested its not getting enough gas when i step on it.
He said a double pumper would be good, is he right or is it timing (or both)
I got to get this thing running good, thanks guys
ANdrew
It has 15,000 miles on it and was rebuilt very thoroughly.
I cant get it to run right to save my life. I dont know what im doing is probably the problem. It has a 600cfm (I think) Edelbrock with electric choke. (Does it say on carb what size it is?)
Problems:
Hesitates constantly (from a stop light, hitting the gas at 35 MPH, col, warm (worse when its warm, not bad when its on high idle cold))
Deasels when you shut it off, sometime will do it even if its still in drive. Almost always when in nuetral.
Popping sound (From carb?) when it hesitates a lot.
RUns great once you get past maybe 1100 or 1200 rpm, fast truck.
What could be causing this? Timing or do i need a better carb, one guy suggested its not getting enough gas when i step on it.
He said a double pumper would be good, is he right or is it timing (or both)
I got to get this thing running good, thanks guys
ANdrew
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Senior User
Joined: Mar 2001
Posts: 320
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From: Fremont, NE
Bad Performance 460
I was thinking about getting the 770cfm Holley Truck avenger carb for my truck, just got my tax return 
Would this be a good carb? is my carb even the porblem?
Would this be a good carb? is my carb even the porblem?
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Joined: Jan 2003
Posts: 82
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From: Louisiana
Bad Performance 460
Since it's Dieseling when you shut it off my guess would be timing.
My 460 has a 272 dur and .504 lift and I run a 750 Edelbrock, not that it's the best but it was the cheapest.
My 460 has a 272 dur and .504 lift and I run a 750 Edelbrock, not that it's the best but it was the cheapest.
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Joined: Sep 1999
Posts: 2,297
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From: Indiana
Bad Performance 460
astamp78, Is the carb idle speed to high?
The model number on the Edelbrocks is on the left front mounting flange facing outward. A 600CFM with an electric choke would be a 1406 then some other numbers.
Did you buy this carb new?
It could be the timing, but if your idle speed is to high this will cause run-on also. A good base setting is around 10 degree's BTDC, with the vacuum advanced hose plugged.
Some of the other symptoms you mention almost sound like it could be running lean.
If this is the problem you can tune the Edelbrocks pretty easy.
Metering rods are usually all thats needed to fatten up the mixure a bit. These can be changed in about 5 minutes. Don't give up on your Edelbrock yet.
The model number on the Edelbrocks is on the left front mounting flange facing outward. A 600CFM with an electric choke would be a 1406 then some other numbers.
Did you buy this carb new?
It could be the timing, but if your idle speed is to high this will cause run-on also. A good base setting is around 10 degree's BTDC, with the vacuum advanced hose plugged.
Some of the other symptoms you mention almost sound like it could be running lean.
If this is the problem you can tune the Edelbrocks pretty easy.
Metering rods are usually all thats needed to fatten up the mixure a bit. These can be changed in about 5 minutes. Don't give up on your Edelbrock yet.
Last edited by Superdave; Feb 11, 2003 at 12:16 AM.
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Joined: Dec 2002
Posts: 1,297
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From: Billings MT
Bad Performance 460
Here is just another idea.
What about the float? If the float is stuck or the needle and seat aren't set right, it will do the same thing. High idle, deisel, and not have any power because you're dumping too much fuel into it. The high idle setting helps because the engine can take more fuel.
Its a suggestion. Do you have blue smoke coming out the tailpipes? That'll tell you if you are running too rich, and that could be metering rods, jets, or float. If exhaust is clean, look at the timing issue.
Since it runs good when above 1100 rpm, I would look into the float even more. You're using as much gas as the carb can dump and therefore eliminate the float. What kind of fuel pressure are you running? Do you have a regulator on the fuel supply?
1990 F250 4x4 460 HD
What about the float? If the float is stuck or the needle and seat aren't set right, it will do the same thing. High idle, deisel, and not have any power because you're dumping too much fuel into it. The high idle setting helps because the engine can take more fuel.
Its a suggestion. Do you have blue smoke coming out the tailpipes? That'll tell you if you are running too rich, and that could be metering rods, jets, or float. If exhaust is clean, look at the timing issue.
Since it runs good when above 1100 rpm, I would look into the float even more. You're using as much gas as the carb can dump and therefore eliminate the float. What kind of fuel pressure are you running? Do you have a regulator on the fuel supply?
1990 F250 4x4 460 HD
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Joined: Sep 1999
Posts: 2,297
Likes: 1
From: Indiana
Bad Performance 460
astamp78, If you can, be a little more specific on the popping.
1100 to 1200 rpm is not much more than a fast idle.
Is this a more of a mild surging or hesitation deal with a bit of light popping in the carb at say light throttle applications or steady crusing, no load, throttle applications?
Or is it an out and out backfiring through the carburetor through the low rpm range?
1100 to 1200 rpm is not much more than a fast idle.
Is this a more of a mild surging or hesitation deal with a bit of light popping in the carb at say light throttle applications or steady crusing, no load, throttle applications?
Or is it an out and out backfiring through the carburetor through the low rpm range?
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