Vapor lock and fuel boiling

[big gear head]

Who is having problems with the current gas with alcohol mixed? My car ran bad for years and left me sitting on the side of the road several times before I figured out what was wrong with it and started using alcohol free gas. I know of several other people who are having problems but don't have access to alcohol free gas. What are the rest of you doing about this? Is there a fuel additive that will take care of it?

[x33rs]

There are things you can do to combat it. We daily drive our classics without issues, using the crappy 91 pump gas we have, with at least 10% ethanol.

For starters I never run any less than the highest octane offered. Lower octane just exaggerates the issue.

I make sure all fuel lines are away from any major source of heat. I find the factory routings to be sufficient. Both the Z and the bird that we daily drive have their factory fuel lines in place.

Proper venting of the fuel system is important and if not vented properly, can sometimes trick one into thinking it's vapor locking.

I also like to use a thick carb gasket (1/4" minimum) to help absorb some of the intake heat. The added benefit is a slight increase in plenum volume. If you want this to be more effective, a 1/4" thick piece of wood is the best heat insulator, with a pair of paper thin gaskets, it's better than the one piece 1/4" thick gasket deal. 1/4" still allows all the factory hook ups without disturbing anything, with the only change that the divorce choke rod needs a bit of adjusting to compensate for the height change.

I always make sure the fuel pump is healthy, some weaker pumps can exhibit a surge issue, or have more trouble pushing/pulling hot fuel.

Lastly, on cars that came with a return style fuel system, I always use it. I see many that are bypassed and the pump dead headed. That keeps the fuel stagnant in the system unless the needle and seat/seats are open.

However even with that said, our Z which is a factory dead head/non return system has never shown any problems with vapor lock, and it's been driven daily for 2 years in the AZ desert heat.

I also make sure the cooling system is up to snuff. I prefer to run cooler thermostats (160-170). The cooler the engine, the cooler everything else is under the hood. Typically our Z runs 185-ish on the hottest summer days when ambient temps approach 110 degrees. It runs cooler during the cooler months obviously, but stays in the 165 range. There is a ton of debate what people feel engine temps should be but the bottom line is, if you want to run a hot stat like a 195, you're going to increase your chances of vapor lock.

I've experimented with blocking the heat cross overs with success but these days, both of our daily drivers are still using their divorce chokes so I have the cross overs open for proper cool weather operation. This hasn't caused any hot start or heat soak issues to date.

Some may suggest to install a pusher pump, which does help fight vapor lock. Frankly I've never found the need for it. I still run the stock mechanical AC pumps on both cars.

Make sure your fuel sock in the tank is in good shape. I run an oversized sock on the cars that is much larger than OEM. I sourced them for a 70's pickup truck and swapped out the smaller units on the cars. Don't recall the part number off hand.

Other little tricks I do is check all OEM brass fittings (if equipped) and I find most internal dimensions are small. I drill them while still leaving enough flare for the fuel line to seal. I also take the shorter metal lines that fit in the cabinet blaster and run glass bead through them at high pressure in both directions in an attempt to extrude hone and soften/enlarge the turns. I've yet to CC one to see if there is a difference, but plan to next time I do one.

It's all just little things in an attempt to help the fuel system.

Of course you can try wrapping things. I tend to not do that because I don't want to disturb the factory appearances.

[big gear head]

I rebuilt a 350 in a '78 Caprice last winter. Everything is completely stock including the emission system. It vapor locks every time it's driven and after it's been shut off and sits for a little while all of the fuel evaporates out of the carburetor. Fuel has to be poured into the carburetor to get it to start again.

I worked on a '55 T Bird a few weeks ago and it vapor locked while idling in the drive way. I had to pour fuel in the carburetor to get it to start again after it cooled off.

I built a 454 for a '85 C10 a few years ago and it vapor locks when driving. It shut off on me a few times before the owner took it home.

My Camaro would shut off on me every time I drove it. When I found out that it was the alcohol in the fuel that was causing it I started running no alcohol fuel and I have no more problems.

I've seen several other people who have been having the same problems. Maybe it's the fuel around here that is causing it, but it seem like there should be something that can be added to the fuel to raise the boiling point so that it doesn't do this.

[x33rs]

I see you're in Kentucky? When I lived in Ohio I remember 15-20 years ago there was a big stink about Kentucky switching to reformulated fuel. May have been further back, my memory is fuzzy. Anyway, not sure if that ever happened but you guys are also starting to get into your winter season, and I believe by now the fuel has switched over to the winter blend. So if you're still getting some warm days, that stuff will vapor lock in a heart beat.

I always hated that in Ohio (they did the same thing) because if you have any of those warm days that so often happen in the fall and spring out there, that winter blend fuel is absolutely horrible for vapor lock. It would always bite me in the spring when you get a few odd warm days in March with temps in the 70's, and Ohio wouldn't switch to summer blend until April or May.

[bluel78]

Attended a Studebaker club meeting a while back and this conversation came up. Sounds crazy but a few members were adding diesel fuel, 1/2 gallon to a tank of gas to give the newer fuel some body and lubricant. Tried it in a 80's 454 dually that loved to vapor lock and seemed to help.

[x33rs]

If you have non alcohol fuel that would certainly help. Seems more and more of those are popping up.

Where I'm located, we have one station that carries it, and it was just built last year. The problem though is that it's only available in 87 octane and I can't run that low of octane in our stuff.

I'm not sure what is out there for additives that might help or if there is anything that actually works. The only thing I add to my fuel is a pinch of 2 cycle oil with TCW3 only for some lubricity and cleaning purposes, since the lead is gone. 1 ounce per 5 gallons of gas.

[JKZ27]

The Pure-Gas website shows Casey's General store near Central city sells 91 octane. Might be worth a look.

https://www.pure-gas.org/index.jsp?stateprov=KY

[big gear head]

Originally Posted by JKZ27

The Pure-Gas website shows Casey's General store near Central city sells 91 octane. Might be worth a look.

https://www.pure-gas.org/index.jsp?stateprov=KY

That is exactly what I'm running in my car and it runs good on that. I have no more problems, but these other guys don't live in the same town, so they can't get their gas there. I've never heard of the pure gas web sight. I'll have to check it out.

[1967 4K]

I live in central Ky. and run Shell or BP high test in my L78 engine and have never had any issues as being discussed here.
Richard

[JKZ27]

That site has a handy map that helped me find E-free gas near me, mainly for my small engines and ATV stuff. I have been using 93 octane, 10%Ethanol in all my Camaros without issue. My 69 and 79 use stock return style pumps and my 68 is return style EFI, FWIW.