I6 lurching while cruising, not while pulling

[slowcobra24]

Hey guys,

My first real post here. On my 65 mustang coupe, I6 with 3speed, it seems to drive fine until you are just cruising at a constant speed. It seems to be lurching. Giving it gas, it seems fine and pulls hard. But go back to cruising and it lurches. It has new cap/rotor/wires/plugs/ignition coil...I am going to get the fuel filter next(haven't changed it since it looks new). Just bought the thing not long ago, and still new to the stang world.

Any usual suspects on this kind of thing(lurching/sputtering, etc...) Thanks in advance!!!

 

[rbohm]

first thing to try is advance the timing until you get a pinging the back off until it stops. another issue to check is vacuum leaks. make sure the carb is properly bolted down, and dont forget the gasket between the carb adapter and the manifold, make sure it isnt the culprit.

 

[slowcobra24]

Well, there seems to be some leaking from around the carb...or at least some gunk buildup around it. I was hoping there is a "common" issue causing this problem. Thanks again for the help...

 

[68er]

you might also want to check the float level.
if it is set a little bit too lean - that could cause surging, as the intermediate jet alternates between lean/correct mixture during light load/high vacuum situations. When you step on it - the accelerator pump gives it a shot of gas, vacuum drops, and the main jet kicks in.

 

[rbohm]

Well, there seems to be some leaking from around the carb...or at least some gunk buildup around it. I was hoping there is a "common" issue causing this problem. Thanks again for the help...

they have the same issues as any other carburetted gas engine does. you might rebuild the carb and make sure everything is good to go with it.

 

[slowcobra24]

thanks guys...gonna replace the fuel filter, and then onto the carb...thanks again