J weaver

Need some help on finding a solution for my 1965 396/425 engine to stay idling after running for an hour or so. The block temperature gauge shows 180 degrees but the car will not stay running at idle speed (900 rpm). I even put in 2 gallons of high octane fuel with every fill up. Any suggestions would be appreciated.

Nowhere Man

Who keeps there car idling for over a hour??? What ignition system do you have?

Vet65te

I thought the same thing when I first read his writeup but then thought he might mean...normal driving for an hour and 'then' having difficulties getting it to idle. Maybe yes, maybe no?
Mike T - Prescott AZ

bluestreak63

Yeah I don't think he's actually idling for an hour. He's going for a drive and then idling in his driveway for a few minutes but unable to stay steady at 900rpms.

When's the last time the carb was looked at/rebuilt?

DansYellow66

I think we need more information. What's the timing set at? Is it all stock or modified? Does it have full vacuum advance to the distributor? Is it the stock Holley? If so, what condition is it in? Exactly what does it do when it dies - idle slowly decrease and stall? Abruptly quits?

J weaver

Yes, you are correct. Good example is coming off the interstate and coming to a stop light. I have to keep the rpm's around 1500 just to get it home. The carb was refurbed 2 years ago. Even though the block temperature shows 180 I feel the gas is getting too hot (boiling). Any thoughts?

Nowhere Man

Is your engine totally stock. Or do you have aftermarket parts Like the ignition system and carb?

J weaver

Totally stock.

mashinter

I had the same problem with my '65 L78. I blocked the heat risers in the intake manifold and wired open the heat riser valve in the exhaust
(my choke is disabled). I also installed a splash pan under the intake manifold. That fixed it for me.

GTOguy

I advise you take the car to a competent mechanic. If you feel it is starving for fuel at idle, you need to pursue that hunch. Either with your own diagnostic skills or those of a technician who posesses them. Best way to solve your issue.

Vet65te

J - Can you give us some details on your 65 like cooling system condition (what's old/original, what's been replaced), engine details like timing, etc?
Mike T - Prescott AZ

DansYellow66

I already asked above - not sure he knows. Kind of like playing blind man's bluff.

J weaver

Sorry but I am limited on supplying some of your information requests. My mechanic is out of town for another 2 weeks so will not be able to supply you these details. I can tell you the radiator was replaced about 20 years ago with an all aluminum one. We also put in a pusher fan in the front of the radiator which really helps with the temperature of the block. However over time (1/2 hour to 1 hour) depending on ambient temp, is when it will not stay running unless I keep the rpm's at 1500 to 2000. Initial start up and until this occurs it runs and idles very well.

Nowhere Man

Sounds like you have a lot of band aid fixes in your car with no real fixes. I suggest you find a better mechanic who knows how GM designed there cars to work Something you have is not working right Did you read JohnZ write up on Corvette cooling. Do a search on JohnZ and cooling 101

bluestreak63

Does this mechanic really know what he's doing?

Where are you located? Maybe someone here lives in the same area and can recommend another mechanic.

Are you going to do any work on it or will all of suggestions we provide be done by a mechanic?