327 300hp Jerky under deceleration

[dick527]

My '64 is very jerky under deceleration. I'm at a loss on how to correct it or what causes it. I have a Holley 650 carb on it and standard point ignition. I do have a starting issue when the engine is hot. I'll check whatever I'm asked to check. I just need advice.

 

[garth64]

Check adjustment on accelerator pump on carb, probably not enough clearance.

 

[JohnZ]

My '64 is very jerky under deceleration. I'm at a loss on how to correct it or what causes it. I have a Holley 650 carb on it and standard point ignition. I do have a starting issue when the engine is hot. I'll check whatever I'm asked to check. I just need advice.

Can you describe more precisely what the symptom is, under what conditions it occurs, any noises that go along with it, etc. ? Did it just develop? Has any work been done on the car recently that might contribute to it?

The more information we have, the better advice we can offer.

 

[bucket]

id say definitely a carb problem...its getting something in the way of air/fuel changes under vacuum...r&r the carb and give it a go..then you will know where to attack
ps
if its messed up a little now it will only run better when its right...

 

[dick527]

Can you describe more precisely what the symptom is, under what conditions it occurs, any noises that go along with it, etc. ? Did it just develop? Has any work been done on the car recently that might contribute to it?

The more information we have, the better advice we can offer.

First thanks for the reply. This has been a pain for a while. The carb is a 650 with mechanical secondaries. Acceleration is fine, cruising is fine but when I take my foot off the throttle the car jerks like a rough idle. This happens in all gears. It has been doing this since I installed the Carb. I'm in China right now working on a project but will be returning home next Wednesday. I plan on working on my car as soon as I get there. Thanks in advance for any help. I sure do miss that car. (and my wife of course)

Dick

 

[JohnZ]

First thanks for the reply. This has been a pain for a while. The carb is a 650 with mechanical secondaries. Acceleration is fine, cruising is fine but when I take my foot off the throttle the car jerks like a rough idle. This happens in all gears. It has been doing this since I installed the Carb. I'm in China right now working on a project but will be returning home next Wednesday. I plan on working on my car as soon as I get there. Thanks in advance for any help. I sure do miss that car. (and my wife of course)

Dick

When you take your foot off the gas, the carb goes instantly to the idle circuits; make sure your idle mixture screws are set properly for highest steady vacuum at normal idle and it's not idling on the transfer slots instead of the idle mixture orifice.