1968 Low idle problem

[cmacias24]

I’m wondering if any of you have ran into a similar problem. I haven’t really taken my car out because my free time has been consumed by my two kids, a 1 year old and a 3 year old. That said, I recently took my car out on 30+ minute drives on the highway and on both occasions my car acted strange. I’m running an edlebrock 600cfm carb (electric choke)with a stock mechanical fuel pump. On a cold start, the car idles fine through the choke process and once it’s warm idles around 700. On both drives, when I get off the highway, the idle drops around so low that it’s on the brink of turning off. The other day I pulled over and doubled checked the air/fuel mixture and it was fine but had increase the idle via the screw. When I got home, I noticed the idle was higher, which is probably attributed to the adjustment I did earlier that day. Yesterday I had the same experience, but this time I noticed that the fuel filter, which you’ll see on the picture, was about a quarter full. It almost seemed like it was starving for fuel. Could I be experiencing vapor lock in the fuel line or a possible faulty fuel pump? From the fue pump, I’m running a stock fuel line, which transitions to a rubber fuel hose, then fuel filter and into the carb. I’m glad this is happening before I install the AC compressor and pulley tensioner.

Thanks in advance,
Cesar

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[CougarCJ]

Using ethanol fuel? Letting it sit for extended periods of time?

 

[cmacias24]

I run 91 unleaded but it does have a percentage of ethanol. It can sit for as a long as 3 weeks.


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[cmacias24]

I spoke with Allen (born1968) and he believes it’s related to the heat and recommended a spacer between the carb and the intake. I went ahead and purchased this edlebrock heat insulator gasket that’s suppose to help and plan on changing my fuel line setup as well, inline filter as well, so that it’ll away from the intake. I’ll update this thread if it resolves my issue in case someone runs into a similar issue in the future.

Cesar


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[cmacias24]

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[Mosesatm]

You may want to also add a bottle of cleaner to your gas.

 

[stangfan]

You may want to also add a bottle of cleaner to your gas.

Probably wouldn't hurt to spray some carb cleaner inside the carburetor also.

 

[robert campbell]

I do not believe it is heat related or fuel pump related. The glass fuel filters let you see what you believe is low fuel to the carb. It is not and they normally look like they are empty. Trust me there is fuel in the float bowl.

It may be as simple as carb adjustment, and proper idle mixture screw settings. Keep in mind every time you change the hot idle by adjusting the idle stop screw the idle mixture screws need to be readjusted. I would also check the timing. Set the timing at at least 12 degrees before top dead center (BTDC). Readjust the throttle stop screw and the air mixture screws. I bet you will be happy.

Rob