1964 Impala 340 HP 409, I’m having trouble with my 4GC carburetor.
- Thread starter 64 SS 409
- Start date
This really works well Don suggested this for mine and it IS A GREAT fit, comes out of the box , bolt on and go, make sure you have steady/good pressure from fuel pump. I would add, the 340 breather will no longer fit because the AV2 has a 5 1/2" opening/throat, so I bought a nice adapter from Show Cars from Bruce that fixed that, or buy a 5 1/2 throat breather, I did end up getting a nicer fuel pump that could deliver the right amount of fuel, test the pressure all stated pressures are NOT EQUAL, just because it says the rating. I still have my rebuilt 4GC and Glass fuel bowl, but the performance of the AV2 and smoothness of the idle, precision of acceleration blows the 1964 technology all to hell. The two vacuum ports are also very important, I chose the right port/driver side because of my MSD Ignition/Distributor, FULL vacuum. Then after it was all installed Don helped me get it dialed in prefect with a vacuum gauge and air/fuel mixture, its not a drag car for sure, but it is very smooth and drives well.
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64 SS 409
Member
Did you use a 1/2” heat spacer also with the adapter, or just the adapter that you got from Show Cars. and is the breather the same part as the adapter, and as far the PCV value goes I guess I can get a inline PCV value and install it between the new carburetor and the oil fill Tube.
thanks
Pat.
thanks
Pat.
Don't give up on that 4gc to quick they are simple carburetors i had one years ago and without going into a long story i found one of the rear floats was leaking around the seam where they are sordered together and was filling up with gas i fixed that and had no more trouble.
Be sure and check for that orifice that tenxal mentioned.
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I used the 1/2" spacer, because you really need to, to help with the vapor lock issues/heat, I should mention I am using the cast factory intake, then I used my original long snout chrome 340 hsp breather with the adapter from Show Cars, that carb gets up there in height for sure, but it all closes and operates just fine. That being said when you first open the hood, it looks a little odd, but that only because I know it should be an inch lower. I didn't want a universal breather, and I did not want to cut or modify a perfect factory (Expensive, now days breather , but I could have if I wanted)
Hope that helps.
I have a TRUE 4GC, 1964 Carb, correct numbers and correct angles, with the glass fuel bowl, I paid almost $1200 for getting it sent off and redone to OEM, in California somewhere (probably Better) specs and color/metal treatment, but it at its best....did not have the response or quickness or precision of the AV2 Edelbrock. I like OEM and original where I can, but when I hit the pedal, I expect quick, fast and great response time. Of course it is a Automatic PG Carb, but I used it on my 4 speed.
Also you had asked about pvc, my 64, 409 uses a system from the back of the intake area with a tube that comes up to the back of the carb, similar to the Road draft version on earlier models, I ordered some parts from Bruce at SC, that allowed me to create a TEE, and then into my Brake Booster, I will have to redirect the full vacuum somewhere else now, but I know my 409 Factory intake has a port as well, but I know that engine needs to breath, so good question, I am not sure what your working with, but there are a lot of knowledgeable guys in here that can help with proper routing, good luck
64 SS 409
Member
Thanks for all the information, I also have the stock cast factory intake that I’m planning on using.
I will get the AV2 carburetor and the spacer from Show Cars, then I will figure out how to get the pvc hooked up right.
I just want to drive it right now on long distance or around town. I will save the original carburetor for later.
thanks.
I will get the AV2 carburetor and the spacer from Show Cars, then I will figure out how to get the pvc hooked up right.
I just want to drive it right now on long distance or around town. I will save the original carburetor for later.
thanks.
64 SS 409
Member
I did check on the orifice, and it is there and seams to be working properly.
thanks.
I absolutely agree, I have been considering it, my problem is I have the small runner heads...817's, smaller valves, etc. not sure how much improvement I would see, for $3-400 dollars, unless I could find some better heads, that would lead to wanting to get back into the engine and replace the cast pistons and add better rods, maybe stroke it ....lol where would I stop........
I get that completely. I'd guess there is 20 hp just sitting there, the 817s can really be pretty good and there seem to be some small port intakes around right right now...you are absolutely right, it never stops. Just grab the low-hanging fruit, I guess.
Looking at your pictures ,choke is closed position . It will patially open or should after starting. The heat stove is not connected any heat source so choke will not operate correct. You say you have to put your foot in it to keep running. When you put your foot in it your are unloading choke manually with linkage. Take and tie fully open that choke flapper. That might be the problem with the way it runs.
Yep agreed, I lost my mechanical choke with the heat tube, when I switched to headers anyways, but then when I switched to AV2, I gained a electric choke, problem solved, for me.
Electric or a manual choke cable could be used on that 4gc carb if stove tube disconnected on account of headers .
Rondecurtins
Well Known Member
Should the tubing for a heat source for the choke be copper or steel tubing? Or does it matter?
Do you have manifold or headers? Copper ??? I would use steel as my own preference . I don't think you can find copper in correct size compared to steel ???