I've been having an issue lately where my car stalls at idle, especially after I drive it for awhile. The problem gets more pronounced with the hotter temperatures we've been having lately. I've never had these issues over the winter. Anyway, someone suggested that I might be having vapor lock issues and that one solution I could try would be to install a fuel cooler. Thoughts? Also, could someone recommend a fuel cooling unit I could try?

 

A fuel cooler can help performance by making the gas atomize better, but yours sounds like it may be a percolation problem. The carb could be getting too hot, especially if the exhaust cross-over port in the intake manifold isn't blocked off (something you do want to do for a summer car). The extreme heat under the carb can make the gas boil out of the bowl and not leave enough for the engine, I've had it happen. Another thing you can do is put a phenolic carb spacer between the carb and manifold. That will insulate the carb, and prevent a bit of heat fron transferring up to it. Also, check your float bowl level. It could be too low, which will just accentuate the above condition.

 

Holleys with their style of bowl are more susceptable heat percolating the gas, so a good aluminum shield and a spacer will do wonders to help shield them. Not sure what carb you're running, but if it's a Holley I'd spend the $35 for a heat shield.

 

Well imagine that! When I rebuilt my carb I took out the spacer. Now, on hot days after the engine has come up to temp, it doesn't like to be started.

Forgot all about them heat shields... Something else I might as well pick up tomorrow at the speed shop

thanks!

 

Thanks for the response Chuck. Actually, I already have a spacer between my carb and intake manifold. I currently have an Edelbrock 6xx, which means I had to install a spacer to get the carb to fit the manifold. I forget the exact number, but its not the 600 CFM though. Man, once it gets hot, the car stalls quite a bit. I experienced that quite a bit today. The first 30 minutes was great, but after the weather and car got hotter, it kept stalling at the lights.

 

Hi Minex,

Just to clear the obvious, your choke is wide open when the engine is hot right?

What are you idling at in gear?

 

edelbrock carbs like to have their float level dead on also try some heat wrap on the fuel pump and line going up to the carb.also a electric fuel pump pushing fuel to the mechanical one on the block helps quite a bit .i have seen some guys run a lil fan blowing on the carb ala L-69 style. my service truck is a 68 dodge A-100 that has a 340 in a box between the front seats so i feel your pain man!!

 

haha... yeah, the choke is wide open. I have an electronic choke on the carb which isn't connected, so the choke is always open.

Unfortunately, I don't have a tach either. I wonder if I am idling too low. Once I let off the gas, the car starts to sputter and die. I can keep the car alive by giving it gas. I'm just worried the car will idle too high during the first 30 minutes of operation and during winter.

 

I know the initial choke opening is spring loaded and is adjusted by turning that black plastic cap on the side of your carb. It's possible to have the choke open according to the spring, but not properly adjusted to a full open position.

Anyway, I don't think that's your full issue. If it were me, I would get the car to temperature where it stalls, then up the idle just a tad (enough to keep the car running) and then start adjusting the idle mixture screws. Once it smooths out, lower the idle slightly, and tweak your idle adjuster screws accordingly for a nice smooth idle. You can use a vacuum gauge if you want to get all technical, but a good ear works just as well. Play with it, paying attention to how the carb and engine responds to turning the mixture screws in and out. When it's all said and done, both screws should be equal in their settings. I've seen guys have one screw turned out .75 of a turn and the other one turned out 2 turns.... Not saying your's is like this, just saying it's something to check.

One more thing. Before you start your car, check to see where your idle adjuster screws are at. They should be about 1.25 - 1.50 turns out. If you've never played with the idle adjuster screws, be careful when you run the screws in or you'll end up screwing up your carb. Just screw them in till they seat, and no more.

That makes me think about something else to check. I've seen guys run the screw in so hard they distort to point at the end of the screw. Pull them out and see if they have any rings around them. If they do, it means somebody seated them to tightly. If that's the case, you might get lucky by just replacing them.

Hope that's not the case, but it gives you something to look at anyway. Hope it helps and good luck.

 

A tach would be helpful, but an experienced "ear" can hit the idle speed pretty well. Curb idle (the linkage stop adjustment on the drivers front corner of the carb), and fast idle (choke linkage on the passenger side) are two different unrelated settings. This may come in handy (choke info on page 8): http://www.edelbrock.com/automotive_...ers_manual.pdf