Rochester 2GV Bad Hesitation

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Shannon Buff

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HELP! I have a 1971 Dart Swinger with the 318 and a Rochester 2GV on top. I have replaced everything from the head gaskets up on this engine - hardened seats, coil, plug wires, plugs, cap, rotor, points conversion, fuel pump, fuel filter, rubber fuel lines, and had the carb rebuilt. I have run a compression check and it shows about 120lbs average and a steady 17-18 inches of vacuum out of the intake. Now here is the problem. I can start the engine and let it warm up and it idles fine. If i quickly crack the throttle it hesitates really bad and will die if i dont release. If i slowly open the throttle it will studder until about 1/4 throttle then straighten up some. It is alot worse when I try to move the car. If i hold my hand over the carb and adjust the air entering the carb with my fingers, It runs great. I have talked with the guy that rebuilt this carb and i just as well talk to the wall. Am I over looking something or does it seem that the engine is needing more fuel? and if so what can i do to fatten it up?

Thanks for your help!!!

Shannon
 
Check the accellerator pump to see if it is shooting fuel into the carb throats.
 
Some of the Rochester 2s have an internal fuel filter (right where the line goes into the carb.) Not sure of your model, the 2CG did as did the model used on the 72 GM products. Of those, some were a bronze material that clogged easily. I was never able to clean them, so I replaced with a paper filter.
 
First off, if it's a stock engine, it does not have a lot of manifold vacuum. A healthy stock engine...and even a slightly modded one should have about 19-21 hg. What you have may sound close, but it's low. I think the timing may be either too low or something is amiss in the distributor causing it to give a low timing signal. Low timing is the number two reason for a low vacuum reading right behind a vacuum leak. I would start by checking the initial timing and playing around with it to see what it does.
 
If it is clogged, you can try this: Start it up, and run it up in RPM a good ways and close the choke. Repeat it several times. A lot of times that will suck whatever it is through the carb and out the tailpipe. That is, IF it's the carburetor.
 
StrokerScamp said:
First off, if it's a stock engine, it does not have a lot of manifold vacuum. A healthy stock engine...and even a slightly modded one should have about 19-21 hg. What you have may sound close, but it's low. I think the timing may be either too low or something is amiss in the distributor causing it to give a low timing signal. Low timing is the number two reason for a low vacuum reading right behind a vacuum leak. I would start by checking the initial timing and playing around with it to see what it does.
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as i move the distributor from TDC to BDC the vacuum does increase, but i am affraid to move it too far and does help the hesitation a little.
 
I did install a points conversion kit in the distributor what else would I look for as far as problems in the distributor. I should also mention that is was a granny owned car and has 65k miles on it. I am trying to give as much info as I can. This problem is driving me crazy!! Thanks for all who have tried to help and who may have more ideas
 
ok i now have the timing set 16 degrees BTC. It runs alot better at highway speeds but hesitates off idle. it doesnt get hot and starts fine. will it hurt to run it like this?
 
Shannon Buff said:
ok i now have the timing set 16 degrees BTC. It runs alot better at highway speeds but hesitates off idle. it doesnt get hot and starts fine. will it hurt to run it like this?
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did you check the balancer to make sure it's not slipped? as i said on the mopar muscle forum....look into the carb and give the pump a squirt. I know you said it was working, but make sure the stream is strong and flows for for a reasonable amount of time. it it squirts and stops almost immediately, you may need to adjust (bend) the pump arm linkage. it might not be operating the pump to the the extent of it's travel. Just a thought. and no, as long as you hear no detonation, the timing will be fine. i would still double check the balancer. if it's slipped, it will slip more. if it comes off at highway speed, it will booger up whatever it comes in contact with.
 
also...something else to ponder. on a stock engine, a failed vacuum advance will cause what you are experiencing. have you checked it? it's worth a shot.
 
thank you for your input it has been very helpful! I will check the advance. I know that when I have my timing light hooked up and the advance plugged in the mark on the balancer does move up on the scale into the BTC marks as I give it gas. in order to check the balancer, would I mark the two pieces with a wax pencil and just keep my eye on it or is there a better way? also the accelerator pump does stream gas about 3/4 of the way down to full throttle. Again thank you very much for the information you are a big help!!
 
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