carb help
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Freshman User
Joined: Aug 2007
Posts: 30
Likes: 0
carb help
Hello all. I have an original Holley 4bl carb on my 390, I want to get a new carb since i am having problems with this one. I cant seem to get the accelerator pump to work, no matter what I try.
I need to know what carb to get, the engine is all stock. The current carb doesn't have a manual or electric choke. Is it mechanical?
What choke should i go with?
I am thinking a 600cfm Holley. Is this good for a truck that is all stock and is just for towing a boat mainly.
I need to know what carb to get, the engine is all stock. The current carb doesn't have a manual or electric choke. Is it mechanical?
What choke should i go with?
I am thinking a 600cfm Holley. Is this good for a truck that is all stock and is just for towing a boat mainly.
Fleet Mechanic
Joined: Aug 2007
Posts: 1,836
Likes: 261
From: Piney Woods of East Texas
The 600 is good size for a 390. If stock it does not need to be that large, a 450 would do. If you have the pull choke **** inside the cab you have a Mechanical choke.
What specific problem are you have with the accel pump. Not squirting, bogging down, flat response. You could just put a carb kit in your existing carb would be a lot cheaper. The holly are pretty simple to work on.
What specific problem are you have with the accel pump. Not squirting, bogging down, flat response. You could just put a carb kit in your existing carb would be a lot cheaper. The holly are pretty simple to work on.
Thread Starter
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Freshman User
Joined: Aug 2007
Posts: 30
Likes: 0
I have no **** in the cab for the choke. It doesnt have any wires running to it for electrical either? I have replaced the accelerator pump already it will not squirt, the pump seems to be pressurized? I cant even get it to squirt when i do it by hand. If i take the carb off the engine and remove all gas from bowls then the accelerator pump will squirt gas. I have no idea what is keeping it from working when the bowls are full.
Lead Driver
Joined: Jan 2003
Posts: 9,893
Likes: 12
From: Ohio
Something is amiss. If you pull the accel pump off bottom of front bowl, remove the diaphram and spring there is a check ball below that. It also could be a rubber flapper(both are basically one way valves), that allow fuel to flow into pump diaphram, but not back into bowls. Make sure this is functioning properly, or pump will not pump(just cavitate or pump back into bowl).
No other reason why it should not work.
No other reason why it should not work.
