Vapor lock
Thread Starter
Le Mans Master
Joined: Jan 2001
Posts: 6,938
Likes: 1
From: San Diego CA
Vapor lock
not sure if it's vapor lock or what but here's the symptom.
Driving the car hard, stop at a store. Come out and restart the car. Requires a lot of pedal to start. Does not want to hold an idle, must keep foot on pedal, give it some gas as I get down the block. first stoplight I get (1 block away) she's idling and acting fine. She does this from time to time and only when driven hard and when it's hot and when I turn it off and return in under 10 minutes. What ya think it is?
Driving the car hard, stop at a store. Come out and restart the car. Requires a lot of pedal to start. Does not want to hold an idle, must keep foot on pedal, give it some gas as I get down the block. first stoplight I get (1 block away) she's idling and acting fine. She does this from time to time and only when driven hard and when it's hot and when I turn it off and return in under 10 minutes. What ya think it is?
Team Owner
Joined: Sep 2001
Posts: 30,958
Likes: 0
From: Middletown Connecticut
Cruise-In IV Veteran
Originally Posted by Cali,68,L-79
Heat plate-WTFO? Eldebrock plopped on a troquer 2 nothing else there?
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Thread Starter
Le Mans Master
Joined: Jan 2001
Posts: 6,938
Likes: 1
From: San Diego CA
Originally Posted by gkull
You need two things to cure your problem. Run 1/2 inch wood carb thermal spacer and If you don't have a fuel return line run one.
Pro
Joined: Oct 2003
Posts: 565
Likes: 0
From: I'm bleeding, making me the victor!
Classic symptom of an aluminum carburetor. Must be an Edelbrock or a Carter! You will need to at least use a thick insulating gasket or some sort of phenolic spacer if you have room.
Thread Starter
Le Mans Master
Joined: Jan 2001
Posts: 6,938
Likes: 1
From: San Diego CA
Originally Posted by PRESSURERAT
Classic symptom of an aluminum carburetor. Must be an Edelbrock or a Carter! You will need to at least use a thick insulating gasket or some sort of phenolic spacer if you have room.
Instructor
Joined: Nov 2002
Posts: 194
Likes: 0
From: Irwindale Ca.
Hi Dave, Check your carb. after you run it hard for a while.
remove the top of the air cleaner and see if it is percolating out of the vent tubes like a coffee pot does.
Also, it may be mearly a fuel line being too close to a header pipe, over heating the fuel, so when you take off again, vapor is locked in the line..I have seen people attach a wooden closepin onto the line near the hot spot and not see the problem happen again...Be sure to color match the clothespin to the engine color.
remove the top of the air cleaner and see if it is percolating out of the vent tubes like a coffee pot does.
Also, it may be mearly a fuel line being too close to a header pipe, over heating the fuel, so when you take off again, vapor is locked in the line..I have seen people attach a wooden closepin onto the line near the hot spot and not see the problem happen again...Be sure to color match the clothespin to the engine color.
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Originally Posted by Cali,68,L-79
Found the plate. How do I run the return line? BUBBA left me with a wood screw into the lines down on the frame down under the fuel pump.
If u want to experiment for cheap just try one of those Fram dual outlet inline fuel filters (I see'm on the shelf most auto stores). This will allow u to run flex rubber (cheap) line (from filter outlet) to that unused vapor return line to the tank. Verify return (vapor) line still connected (and open enough to flow fuel) to top of fuel tank. But I'm not sure a '68 had a vapor return line as they were vented fuel systems. Anyways using one of those filter outlets to recirc fuel back to the tank should help.
For a more permanent fix the recirc line should have a small orifice (0.040") to limit/reduce flow. I'm in the process of building a steel tube fuel line with recirc for my '74. I drilled, tapped and installed a bushing right in my carb inlet for my recirc and a press sensor. Looks ugly but I will know what fuel press is right before it goes past needle & seat while I maintain fresh fuel in my line even at idle.
Good luck and good night.
cardo0
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Originally Posted by Stinger66
Hi Dave, Check your carb. after you run it hard for a while.
remove the top of the air cleaner and see if it is percolating out of the vent tubes like a coffee pot does.
Also, it may be mearly a fuel line being too close to a header pipe, over heating the fuel, so when you take off again, vapor is locked in the line..I have seen people attach a wooden closepin onto the line near the hot spot and not see the problem happen again...Be sure to color match the clothespin to the engine color.
remove the top of the air cleaner and see if it is percolating out of the vent tubes like a coffee pot does.
Also, it may be mearly a fuel line being too close to a header pipe, over heating the fuel, so when you take off again, vapor is locked in the line..I have seen people attach a wooden closepin onto the line near the hot spot and not see the problem happen again...Be sure to color match the clothespin to the engine color.
BTW nice '66. Good night. 
cardo0
Safety Car
Joined: Jun 2001
Posts: 4,004
Likes: 2
From: Severna Park Md
One option to restoring the return line is to get a Mopar style inline filter. Install it between the pump and carb. It has one inlet and two outlets. Connect a hose from the smaller of the two outlets and snake it back down to the return line on the frame.
