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Old 04-21-2012, 11:59 PM
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Vapor Lock Help

Hey everyone, ive got a 59 chevy truck with a 1980 454 motor.
It was fairly hot today and I noticed at idle the truck would run fine but it was running at a little higher RPM than normal. Under moderate acceleration it would sputter kind of like it was running out of gas.

My thought is its a vapor lock problem.

Running an edelbrock 750cfm carb and mechanical fuel pump with the bypass line blocked off...

any ideas how to fix the vapor lock?

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Old 04-22-2012, 07:57 AM
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Try moving the fuel lines away from any heat source, if that's not possible, insulate them from the heat, and putting a phenolic spacer under the card for starters.
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Old 04-22-2012, 08:21 AM
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Quote:
Originally Posted by chevyrestore
Hey everyone, ive got a 59 chevy truck with a 1980 454 motor.
It was fairly hot today and I noticed at idle the truck would run fine but it was running at a little higher RPM than normal. Under moderate acceleration it would sputter kind of like it was running out of gas.

My thought is its a vapor lock problem.

Running an edelbrock 750cfm carb and mechanical fuel pump with the bypass line blocked off...

any ideas how to fix the vapor lock?
Its not vapor lock. If you get vapor lock it wont run. You could be boiling fuel in the carb a little or something else could be failing under the hot conditions.

Vapor lock causes a vapor pocket in the fuel line that fuel can not pass through so it kills the engine.
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Old 04-22-2012, 10:50 AM
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how thick of a spacer should I get? Will any spacer work or does it need to say phenolic spacer?

Last edited by chevyrestore; 04-22-2012 at 11:07 AM.
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Old 04-22-2012, 11:12 AM
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Quote:
Originally Posted by chevyrestore
how thick of a spacer should I get? Will any spacer work or does it need to say phenolic spacer?
If you decide to use a spacer, something that doesn't conduct heat. Like T-Bucket said, it may not be true vapor lock. Also, if you go extreme with the spacer thickness, it can change the motor's characteristics, I'd go with 1/2 or 3/4 inch. The style does the same, 4-hole vs. open. I forget the particulars, but you can research that.
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Old 04-22-2012, 11:33 AM
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found this one if you guys think itll do the job, its either this or 1" from what I found. Dont know if I should go with 1/2 or 1"

http://www.ebay.com/itm/1-2-Phenolic...176172&vxp=mtr
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Old 04-22-2012, 11:45 AM
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Don't assume vapor lock. In the one out of xxxx times I've seen it, the car was parked for a while after being very hot and caused problems with restarting.

Did the truck run fine until just recently? Does it still hesitate when you pull away? Still idles fast?

Check for a vacuum leak.
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Old 04-22-2012, 11:55 AM
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well either way the spacer would help correct? If so I should probably just put it on anyway. The truck was running great, it was super hot outside and the engine bay was just radiating with blistering heat, it was running fine before but this was the first real heat of the season and its cooler today and running fine again. No visible vacuum leaks anywhere.

My gut feeling is the fuel was boiling in the carb just because of how hot the air was when I popped the hood at check everything. If anyone has been in a paint booth while a car was baking the heat was almost like that...super hot.

Im assuming it was that hot just because I was in stop and go traffic on the city streets for a little while and it was pretty hot outside
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Old 04-22-2012, 12:09 PM
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Quote:
Originally Posted by chevyrestore
well either way the spacer would help correct? If so I should probably just put it on anyway. The truck was running great, it was super hot outside and the engine bay was just radiating with blistering heat, it was running fine before but this was the first real heat of the season and its cooler today and running fine again. No visible vacuum leaks anywhere.

My gut feeling is the fuel was boiling in the carb just because of how hot the air was when I popped the hood at check everything. If anyone has been in a paint booth while a car was baking the heat was almost like that...super hot.

Im assuming it was that hot just because I was in stop and go traffic on the city streets for a little while and it was pretty hot outside
A spacer will help the carb run a little cooler. If the carb getting hot enough to boil the fuel then yes it will help. Don't automatically assume fuel just because it is heat sensitive. Many electronic components will start to break down once they reach a certain temperature.
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Old 04-22-2012, 03:39 PM
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ok then judging by the fact that it would idle smooth but a little higher than normal and sputter under acceleration (not just on takeoff but even if holding the pedal half way down it will continue to sputter while moving) what would you think the problem would be?
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