460 running like crap
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Joined: Jul 2008
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460 running like crap
Hi everyone I have a 1974 hi boy.
The motor has been swapped out with a 1973 460 with from what I was told is a Carter AFB 4 barrel. I don't know much about motors but I am trying to learn.
Anyways the truck runs good to start but after a couple of minutes it starts to get boggy and backfires every once in a while, usually around 45 to 55 MPH. Once it starts doing that half the time you can floor it and have very little response. I've looked at the carb thinking that is my problem but all I get is confused I have no idea where to start. I've checked the timing on it and it is dead on. I bought the truck about a month ago and the guy told me it has new plugs and wires and cap but ya never know. Where should I start and if anyone could teach me a thing or two about this carb I would greatly appreciate it. I know nothing about the carb so any little thing will be helpful. The only things I figured out is the choke plate and the throttle ha ha I'm so lost. THANKS
The motor has been swapped out with a 1973 460 with from what I was told is a Carter AFB 4 barrel. I don't know much about motors but I am trying to learn.
Anyways the truck runs good to start but after a couple of minutes it starts to get boggy and backfires every once in a while, usually around 45 to 55 MPH. Once it starts doing that half the time you can floor it and have very little response. I've looked at the carb thinking that is my problem but all I get is confused I have no idea where to start. I've checked the timing on it and it is dead on. I bought the truck about a month ago and the guy told me it has new plugs and wires and cap but ya never know. Where should I start and if anyone could teach me a thing or two about this carb I would greatly appreciate it. I know nothing about the carb so any little thing will be helpful. The only things I figured out is the choke plate and the throttle ha ha I'm so lost. THANKS
Postmaster
Joined: Jul 2003
Posts: 2,544
Likes: 2
From: okc
my first guess is the accelerator pump on the carb is shot...its the thing that gets pushed down when you press the throttle....other than that the only other problem i see it that it has a carter on it...
Hotshot
Joined: Dec 2003
Posts: 18,423
Likes: 9
From: iowa
actually it is entirely possible you have a fuel delivery issue especially since you said it starts out ok but begins to bog down and backfire (possible cause for backfire is lean condition) first check and probably replace your fuel filter, next would be to check the output of the fuel pump and lastly especially with the year it's entirely possible the intank fuel filter sock has become clogged up with crude from the inside of the tank and probably needs removed and cleaned out.
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