1964 Impala 340 HP 409, I’m having trouble with my 4GC carburetor.

[64 SS 409]

I had the carburetor rebuilt at a good shop, but it hesitates from idle to acceleration, and some times it will just dye out, like lack of fuel. When I’m driving on the freeway it will run fine for a little while but will want to dye out every once in a while like it’s starving for fuel, if I keep my foot in to it I can keep it going, I have to floor it and it will keep going.

any help will be very appreciated
thank you

 

[blkblk63ss]

Buy a pressure gauge check fuel pressure from fuel pump to carb. Check for bad rubber connectors ( sucking air )in fuel lines underneath car and at sender unit at tank . Check for free flow from sock on sender unit in fuel tank This will eliminate fuel delivery to carb. Then if ok, carb will be next concern. Do you have correct gasket under carb.

 

[64 SS 409]

Thanks for the information, I will check the fuel pressure. Every thing has been replaced. New fuel lines front to rear, sending unit in tank and fuel pump.

thanks

 

[64 SS 409]

i will check on carb gasket also. Thanks
Pat

 

[blkblk63ss]

Also is that filter in bowl ok.Not plugged. Choke will be wide open when engine is hot.

 

[La Hot Rods]

What distributor are you using?

 

[64 SS 409]

Fuel filter and bowl new, Im pretty sure the choke is wide open but I’ll make sure that it is.
I installed a new Pertronix distributor.

 

[blkblk63ss]

Check your accelerator pump in carb. You can check it by looking down carb while idling and accelerate carb linkage a short quick burst and look for two separate squirt 's of gas going down to plates.

 

[64 SS 409]

I will check the accelerator pump in carb Later today.
what do you think about the jetting in the carb, I was told that they can be changed with the carb on the motor, by the guys who rebuilt it. I’m wondering if that maybe part of my problem.
thanks
Pat.

 

[pvs409]

Check your accelerator pump in carb. You can check it by looking down carb while idling and accelerate carb linkage a short quick burst and look for two separate squirt 's of gas going down to plates.

it sounds like the accelerator pump to me also

Paul

 

[55Brodie]

What is the turquoise tape on the manifold for? Assuming no vacuum leaks my vote is for the accelerator pump shot adjustment.

 

[blkblk63ss]

I will check the accelerator pump in carb Later today.
what do you think about the jetting in the carb, I was told that they can be changed with the carb on the motor, by the guys who rebuilt it. I’m wondering if that maybe part of my problem.
thanks
Pat.

If those jets are original for the carb and engine application then they should be ok. But you don't know that, so if the rebuilder did change them or not you would have to question them on that. That is a possible problem . I once experimented with jets several steps , got to where you had to feather the gas no power ,too lean

 

[427John]

Am I missing something or is there no pcv valve in the line from the rear carb base to the oil fill tube,if not that would be a massive vacuum leak.

 

[blkblk63ss]

Am I missing something or is there no pcv valve in the line from the rear carb base to the oil fill tube,if not that would be a massive vacuum leak.

Good question . I see the choke stove tube not going to a manifold heat source . Not electric so has to be heat to work for choke to open. I think it is blocked off laying on valve c. If you have headers ,no source for tube you can run a manual choke if you need choke. If not you can dial the choke cap to open choke flap.

 

[Gofish]

Could you be having an issue between the idle and transfer circuits? Sometimes a bit of dirt in the transfer slot or holes is all it takes.

John

 

[64ss409]

Am I missing something or is there no pcv valve in the line from the rear carb base to the oil fill tube,if not that would be a massive vacuum leak.

No PCV valve in 1964. Instead there is a .100 orifice at the 90 degree elbow at the base of the carb.

 

[blkblk63ss]

Back in 1977 I had a service station (one year only I had enough long hours , hard to find good help )I tuned up a Ihc truck with a v8. The guy picked it up and came back within five minutes. He said "did you drive the truck ". I said "no". He said "go drive it" He wasn't mad just telling me what it was doing. . He said it was doing the same thing after I tuned it , but did not tell me that before I tuned it. I drove it and on the street to accelerate and trying to get up to speed it just fell on its face ,no power. So he leaves it and I checked all the ignition and it checked good. So I thought has to be fuel , but I had replaced fuel filter so I knew it was ok. Checked fuel pressure getting plenty of fuel So I pulled top of carb and there was a piece of some thing ? stuck in one jet . Cleaned it out , road test and was ok. I never charged the guy , bought his gas from me and I did not have to much time in it finding the problem. Little simple things like that can really affect the performance of a engine.

 

[64 SS 409]

Thanks for the help every one, I’m going to look in to all the suggestions. I’m thinking about changing the carburetor to a Edelbrock for now just so I can drive it, I have rebuilt very thing mechanical, like motor, transmission all suspension, My question is, is there a Edelbrock carb that will bolt to my original intake manifold, so I can use all my existing PCV stuff.

Pat

 

[64 SS 409]

What is the turquoise tape on the manifold for? Assuming no vacuum leaks my vote is for the accelerator pump shot adjustment.

The tape is so nothing can get down in the motor, I keep the carburetor covered also when the air Cleaner is not on while the car sits for awhile. I’m going to check the accelerator pump shot also. Thanks

 

[Don Jacks]

Thanks for the help every one, I’m going to look in to all the suggestions. I’m thinking about changing the carburetor to a Edelbrock for now just so I can drive it, I have rebuilt very thing mechanical, like motor, transmission all suspension, My question is, is there a Edelbrock carb that will bolt to my original intake manifold, so I can use all my existing PCV stuff.

Pat

The eddie carb bolts right on but you'll need to get a 1/2 inch heat spacer and put it between the carb and manifold.Go with an AVS2 650 CFM size for best results.