vapor lock

redone

New Member
Jan 16, 2003
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For the past year or so I've been upgrading my '66 Coupe with a V-8 suspension and drivetrain (yes I've got an I6) just so that I could take advantage of better brakes and such. Well, I've changed all of the I6 parts over to V-8 and now I was wondering if I might have a problem with vapor lock if I decide in the future to put in my 351W.

I've been told that the I6's gas line is too small in diameter to feed a V-8 motor. Is this true or is it just someones preference? I always thought vapor lock was caused my having to fuel line too close to the engine. It would heat up the gas in the fuel line producing vapor (gas). Gas follow problems.
 
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Unless you are planning on cutting and splicing the I6 line (which I don't recommend) you'll have to change to a V8 fuel line anyway. The I6 line comes through the fender well behind the shock tower and the V8 line comes in front of the shock tower near where the fuel pump is located on the V8. Using the V8 line will minimize the amount of rubber hose that you have to use, which is what you want to do. Besides those cars are pushing 40 years old, a new fuel line is cheap piece of insurance I think.
 
I doubt that the 6 cylinder cars had smaller fuel lines , the V8's had 5/16 lines which is plenty enough for most motors. Now if oyu're talking about building some serious HP into that 351, then you may want to upgrade to 3/8 or larger lines. I'm running an elcheapo Purolator low pressure electric pump ( 30 gal/hr) feeding a 400 hp 302 roller motor with 3/8 lines. Most people go overboard on fuel lines, most engines don't need a huge volume of fuel to feed them.
 
Vapor lock is caused by gas boiling in the floats, which forces it out the jets, flooding your engine. I don't think that you would have a problem with vapor lock so much, as you would with fuel starvation. It would be a good idea to run new lines anyway. It's not hard or expensive.

-Shaun
 
D.Hearne said:
And where do we put those clothes pins? :shrug: Or should I ask :D :lol:

:nonono: Hmmm, anywhere that isn't already pierced I guess, unless you really like pain. I'd be more specific, but I'm not sure if I can say nipple on the family site. ;)

Actually You can just clamp them along the fuel line anywhere you suspect heat build up. Wood disipates the heat pretty quickly. Sounds strange I know, but it honestly works.
 
Pakrat said:
:nonono: Hmmm, anywhere that isn't already pierced I guess, unless you really like pain. I'd be more specific, but I'm not sure if I can say nipple on the family site. ;)

Actually You can just clamp them along the fuel line anywhere you suspect heat build up. Wood disipates the heat pretty quickly. Sounds strange I know, but it honestly works.

Cool tip, I did not know that.
 
I recall the close pin trick but never tried or thought about what it actually did. I learned earlier this year that it was possible to have vapor lock happen on EFI systems too, the hard way :bang: :bang: :bang: I have a 95 E150 van with an EFI 351W, and when on Vacation back in june, we were climbing up out of the canyon from Hoover dam, running about 25 mph, the engine wasn't overheated, but the engine fan wasn't on, needless to say it gets REAL warm in that box the engine is in when there's no air flowing thru it and WA-LA : Vapor Lock