Hot Rods What is this vapor lock

Hi Guys,

64 comet 144 inline 6, nothing special.

Car runs and drives great. I noticed this car has always had issues after hot shutdown, if I restart within 3 minutes-25 minutes, I have low idle, and a little dark smoke coming out of the tailpipe. It will stall sometimes, but mostly just idles low. Once being driven for an additional 5 minutes, all problems go away and its back to normal.

I dont think its flooding, as I cant smell fuel, or see fuel coming out externally from the Carburetor.

As a fuel injection child, this problem perplexes me. I also noticed I have the same issue with my 69 skylark, but not nearly as pronounced. In that car I just have longer starter crank time.

Is this just how the old things were?

 

Nope.
Automatic choke? Is it adjusted right?

 

I don't have any proof, but I think the ethanol fuel makes the heat soak problems way worse.
Not to say the choke and float levels don't need to be looked at.

 

Vapor lock is more prevalent in modern fuels, especially those with an Ethanol blend that the fuels of old. That Falcon has the intake and exhaust manifold on the same side and that just adds a ton of heat when you shut it off. Some have had success with a phenolic spacer (or even on e made of hard wood) to isolate some of the heat.

 

Ethanol being a problem is good logic. Alcohol has a lower boiling point than gasoline. But evaporated fuel either in the bowl or between the pump and the bowl will not make one run fat. Black smoke and poor idle suggests that it is running fat not lean.

The theory behind vapor lock is that a pump cannot pump vapor. That would happen between the tank and the pump not after the pump. where we are having problem with heat soak is after the pump. Just food for thought.

 

Could be percolating in the bowl and pushing it through the boosters into the intake. Or maybe fuel line pressuring up enough to push gas by the needle and seat.

 

That makes sense. He said that it wasn't but that makes good sense to me.

OK Larry that's freakin scary, man. if you make sense to me what does that say about you.

 

I used to have the same problem in my 1965 Mustang. Inline 200. Bad idling, stalled while driving, missed starts, puffs of smoke...I thought it was vapor lock until I seen some sweat on my distributor after someone pointed it out to me while I was living in Columbus, Ohio, very high humidity. I changed the cap and plug wires and never had the problem again. The wires had some very fine cracks that you could barely see.

 

Benno, I've never claimed to be sane.

 

Pacific north west, I have removed the choke.

Open all the time

 

This is what I think the problem is.
Or hope what the problem is

 

You can pull the air cleaner and look down the thoat of the carb after you shut the hot engine off and see if you can see gas dripping from the booster onto the top of the throttle blade. Another tell (maybe) would be gas on the throttle shaft on the outside of the carb.

 

Someone told me to wrap my metal fuel lines with insulation. Where can I find some insulation for that?

 

I get mine from Summit, Moroso makes it. You might be able to find it cheaper somewhere else. We used to use tinfoil, but I don't think it worked very well.

 

Real old timer trick I saw that worked. We had a Ford stock car with a worked 460 in it. We suspected vapor lock/ percolation. So my partner whips out a bag of wooden spring clothespins... snaps them on all up the fuel line. End of problem. The wood acted as an insulator.

Any decent speed shop should have insulation material or try the oldest real parts store in town. I've seen fuel lines wrapped in tin foil.

 

LOL I saw many an old ford 6 with wooden close pins on the fuel line years ago.

Did it work, well sometimes things work because you think that they will.

I have done the tinfoil trick too by the way. You got to put the shiny side out.

 

ok im going to tinfoil it

 

Agree with heat soak. My Chevy II with fenderwell headers will do it pretty much anytime I shut it off over 190 degrees. Heat builds up in carb and after a few minutes will come to an audible boil with fuel foaming out of boosters and down bores. Have to crank with throttle wide open to clear. Added phenolic spacer and helped some. Heres one made just for a Ford 6. http://www.dearborncl***ics.com/car...cylinder-falcon-ranchero-comet-1960-1968.html

 

One way to check if it is definately vapour lock is to tempoararily instal an electric pump down at the tank. If the problem disappears, remove the electric pump and then try the tricks above. Air conditioning suppliers sell tube insulation for refigerant lines, its black neoprene, and very efficient.

 

Too bad it's discontinued

 

https://m.summitracing.com/parts/hs...vQM4TXWjuIwza_xSPHfGm7EzgxHcjNQuS-BoCOsLw_wcB

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Sent from my iPhone using The H.A.M.B. mobile app

 

Oops, sorry. Here's another one. http://cl***icinlines.com/products.asp?cat=46

 

I thought you put the shiny side in... Or maybe that was for baked potatoes.

 

I have a couple of aluminum clothespins on my avatar's fuel line. Not sure it does much but people ask about them.

 

I say clean all your ground connections and the battery positive too

 

There a seller on E-Bay that sells phenolic spacers for carbs. I bought 2 for my small base WCFB's at 1/4". I know he has them for large base too and 2 barrels. Perhaps he makes 1 barrels also.

 

having a samaler problem with my 351 , gotta crank the hell out of it to get her to start after its warmed up

 

I've had cars with the timing a little too advanced which made the problem much worse. Slow crank + the vapor lock left me stranded more than once until it cooled off.

 

Tooooo funny!!! Shiny side out indeed!!!! I have tinfoil on the gasline of my shovel to try and keep the thing running at low speed hot.... it seems I might be having the same problem but the tinfoil, shiny side out aint workin....

 

My shovel never has any problems hot or cold. of course it only gets up above 100 here about 2 or 3 weeks a year.

We used to have problems with those damned Keihin carbs in the heat when they first started using them. I think that was what made the S&S Super so popular.