64 1/2 260 Help

[Ndeininger]

Hey all,

Posting for my Dad who isn't too tech savvy. He has a 64 1/2, with a 260 and auto trans. He has had the car for several years and has recently run into an issue he is struggling to figure out. Car runs great at WOT but at idle it when cruising at highway speed it will sputter and run rough in general.

He started with the carb and rebuilt the Holley that was on it. No change. Put on an edelbrock that he had laying around. No change. Robbed the new distributor off of my 68 289. No change. Wired this distributor straight from the battery to rule out ignition switch. No change. Plugged the PCV valve to determine if valve had been stuck open. No change. Car does have a new fuel pump so he is thinking it is something ignition related.

Any thoughts?

Thanks guys.

Nik

 

[General karthief]

Is he still running points?

 

[Ndeininger]

Is he still running points?

Yes sir. Thanks for the response.

Nik

 

[General karthief]

Don't leave the distributor hooked to 12v, it will burn up the points.
Start with the basics, check points, actually I'd replace 'em and a new condenser, check the cap and rotor.
does it have a lot of miles on it?

 

[1320stang]

Plug gaps?

 

[Ndeininger]

Don't leave the distributor hooked to 12v, it will burn up the points.
Start with the basics, check points, actually I'd replace 'em and a new condenser, check the cap and rotor.
does it have a lot of miles on it?

Points are good and distributor was a new one I had just put on my 289. Didnt leave it hooked up ro the 12v supply for long.

Thanks again.

 

[General karthief]

Pull the vacuum advance hose and plug it, see if it runs better at part throttle cruise.

 

[Ndeininger]

Pull the vacuum advance hose and plug it, see if it runs better at part throttle cruise.

We're finally tried this last weekend. No difference. Vacuum line that runs ro the transmission was cracked so it will be replaced but no difference when it was plugged either. Thanks for the tip.

 

[General karthief]

The coil may be breaking down, may not be noticeable at wot, go out at night and start it up, let it warm up and look at the plug/coil wires in the dark, look for arching to a ground or between wires.