Vapor lock fix

Hi all! 409/425 guy here and I've been having huge problems with vapor lock pretty much ever since I acquired my car here in Florida.

Did all kinds of research and gathered all sorts of opinions from A to Z - replace fuel pump, install a fuel pump assist, replace the fuel lines, replace the fuel filter.... I heard all recommendations known to man.

Until one day, one particular mechanic looked me in the eyes and said forget about everything you've heard - All you have to do is wrap your fuel lines in insulation tape, which you can get at any parts store for around ten bucks.

Spent a few hours meticulously wrapping all lines....problem solved.

I have had absolutely no issues with vapor lock ever since and it appears as if my particular issue was a matter of the lines simply getting too hot. Anyway, just wanted to document/share my fix as I know I'm not the last person who will experience the vapor lock issue.
 

1964SuperStocker

Well Known Member
Supporting Member 3
Hi all! 409/425 guy here and I've been having huge problems with vapor lock pretty much ever since I acquired my car here in Florida.

Did all kinds of research and gathered all sorts of opinions from A to Z - replace fuel pump, install a fuel pump assist, replace the fuel lines, replace the fuel filter.... I heard all recommendations known to man.

Until one day, one particular mechanic looked me in the eyes and said forget about everything you've heard - All you have to do is wrap your fuel lines in insulation tape, which you can get at any parts store for around ten bucks.

Spent a few hours meticulously wrapping all lines....problem solved.

I have had absolutely no issues with vapor lock ever since and it appears as if my particular issue was a matter of the lines simply getting too hot. Anyway, just wanted to document/share my fix as I know I'm not the last person who will experience the vapor lock issue.
I haven't put on any insulation yet but I will be. I don't like how close my fuel line is to the Hooker Headers I'm running.
 

El Rat

Well Known Member
Insulation wrap is a band-ade. You’re problem will come back unless you live in Alaska. Chevy made thousands of 409’s if they had an inherent vapor lock problem it would have been fixed re: 5/16” return line back to the tank. My 09 is stock circa 1963. Where I live the average daytime temp in August is 98 F. I went to a “street” show Saturday morning and Saturday evening; this ride required me to idle for 30 minutes at a time the max SW gauge read 205 with the heater on.
Me thinks ya got a problem that will come back.
 
I was thinking have you checked to see that return line is open and flowing fuel back to the tank some former owner might have pluged it to get more fuel pressure witch you don't need

4speed, I really appreciate that suggestion... I did make sure that it's flowing properly as I have the entire line refabricated and replaced the line shortly after I got it (car came with a cylinder-shaped, after market Wix fuel filter, and I found a factory-correct glass bowl filter that I installed so I had to change out the line as the third return 'port" is in a different location on the filter).
 
A few pics... Not sure if you can tell from the pics, but I need to refabricate the return line, as it's not positioned correctly from an aesthetics standpoint.
 

Attachments

  • IMG_20200811_062855.jpg
    IMG_20200811_062855.jpg
    41.9 KB · Views: 53
  • IMG_20200811_062844.jpg
    IMG_20200811_062844.jpg
    75.8 KB · Views: 52
  • IMG_20200811_062908.jpg
    IMG_20200811_062908.jpg
    69.1 KB · Views: 51
  • IMG_20200811_062812.jpg
    IMG_20200811_062812.jpg
    70.9 KB · Views: 50
  • IMG_20200811_062828.jpg
    IMG_20200811_062828.jpg
    73.7 KB · Views: 51

rstreet

Well Known Member
Supporting Member 17
I found that a set of “fiber” insulators under the carbs helped big time with my driver 61. Also timing rate of vacuum advance and total vacuum advance helped drivability.
Robert
 

427John

Well Known Member
So did the car experience vapor lock before you re did the fuel lines?Also do you run ethanol free gasoline?While it may not be the cause it can contribute to it or make it worse.As rstreet pointed out ignition timing is important, it can greatly affect underhood temp which can cause vapor lock on a rig that wouldn't otherwise experience it.
 
Rstreet, are those basically the thin "pads" that the carbs rest on? That's another suggestion that I was looking into.

I actually have a guy coming over to help adjust the timing next weekend, as it is two degrees off and it's a task that's a little out of my reach...I appreciate you guys providing that input.

It was definitely a pain in the ass to wrap the lines, is I had to do it in small pieces. It was time well spent though! As mentioned, if the problem does come back I will be sure to keep this post updated.
 

Don Jacks

Well Seasoned Member
Supporting Member 3
If you don't have heat spacers under the carbs,do install them.With aluminum carbs such as AFB's and Edelbrock it's easy to boil the fuel in the floatbowls on a hot shut down and restart.These simple add on devices have solved your type of issues most of the time with today's alcohol laced fuel.
 
Top