vapor lock

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johnpaulny

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Jun 7, 2013
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I had my '63 convertible delivered today - very happy, a true 60000 mile car. Then the fun went south. I drove for a while, stopped at a store and 10 minutes later the car cranked endlessly. It is a very hot day so I suspect vapor lock. My previous "64 did this too but not as bad. Has anyone else had this problem? What is the solution? It also seemed like an anemic crank - I suspect the battery is undersized, adding to the problem.
 
Good news, bad news thing. Bad news is that you cant get rid of it completely. Todays fuel loves to boil and gas is no longer blended for carburetion. Good news is an easy fix. Replace your carb base gasket (which you will find is thin paper) with a thicker composite one. Get a base gasket for an 85 Ford truck with a 460. Fixed many and it works quite nice. It stops the boiling in the carb and minimizes the fuel foaming on fire up after it sits in a hot soak. Only issue is what foaming is left after it fires (usually mid 90's out). After it starts you may have to hold the gas down for about 10 seconds for the bowl temp to stabilize. This works well on both the Autolite and Edelbrock carbs. My 65 started like crap at 80 deg and the fix was night and day difference. As far as the anemic crank, make sure somebody didn't jack up the base timing to cure the other problem.
 
Thank you. Now I'm more concerned about the timing, which is beyond what I'm comfortable with (I'll have to have my mechanic check that).
Also, regarding vapor lock, will aviation fuel help the problem? Thanks again.
 
AT 110 + octane av gas has a major disadvantage. Octane is all burn time. It is slower to burn which would make it less efficient in an engine designed to run 91 octane (or close to). You may find that it runs ok but in the long term it will be a carbon buildup nightmare. Ford had several bulletins years ago where people were running their 87 octane cars on 91 octane (Taurus 3.8 liters but the principle applies), They suffered from premature carbon buildup which led to poor performance. I ran into several cases of it in other cars as well. Bottom line, too high of octane is a waist and can actually be detrimental to the life of the engine. Try the base gasket idea. I promise you results.
 
Thank you, I really appreciate the octane advice, I'll stick to 91-93. Regarding the vapor lock, I am not so sure that is the problem. I've only had the car 2 days so today was second drive. First start today it fired up immediately, runs smooth as silk. Drove it for about 20 miles, no hesitation, feels powerful. Today was cooler than yesterday and wanted to see if it would do it again. Parked in my driveway, waited 15 minutes and it wouldn't start. Tried again in 30 minutes, an hour, 2 hours, 3 hours, it won't start. That doesn't sound like vapor lock anymore. Any ideas? Again, it's so smooth when running, so i doubt it is fuel filter or fuel pump but i'm a novice with all this.
 
Depends on what it takes to get it started. I am assuming you have a 4100 Autolite carb. If so, you may have an oozing or drippy power valve. Easy to replace and available without having to spring for a kit. If you have an Edelbrock or an older Carter AFB the power circuit has mechanical metering rods so this does not apply. IF you have a Holley the power valve idea is back in play. Does it fire at all when this happens? Can putting your foot to the floor (or maybe 1/2 to 3/4 down)?. This would be flooding and the carb is the issue. If there is no fire whatsoever then you think spark. More questions....does it still have points or is it a Pertronics conversion (if it is points you owe it to yourself to buy the electronic ignition kit...cheap and easy to install) If it still cranks hard and slow during this time your system voltage could be dropping low enough to screw up your spark. Battery, cables and/or starter possible causes not to mention the timing issue we talked about earlier. No on the filter for sure since it runs ok under higher fuel delivery and no on pump unless it fires and dies as the carb bowl runs dry. Hope this helps.
 
Thanks - this is very helpful. Started immediately this morning - barely one crank and it's running. Then I drove it and noticed it is a little rougher after warming up and also pings on acceleration after warming up. Got home, let it sit - won't start. To answer your question about whether it fires at all when it won't start - no, just cranks without any sign of wanting to start. Battery is new. I am almost certain it has points (ie, no electronic ignition). Thanks again for your help.
 
No problem. Few more thoughts though. You dropped a few good hints of the problem. Ping means over advanced timing. Your mechanic can iron that out but have him put on the Pertronics ignition first. 2nd hint...."one crank and its running". Though this seems ideal it is actually unnatural. I have my choke set well for cooler running and I still have to pump and crank it over a little longer than that just to fill the fuel bowl before it lights. You are running too rich. Back to the power valve theory. When it is hot you are likely loading up with too much fuel. Good luck!
 
I got my car back. Mechanic replaced points/condenser with Pertronix electronic ignition. He said points needed to be changed if I hadn't done that anyway. He also fixed timing. He test drove it, said it was fine. I went to pick it up and it didn't start. He got it started. He asked if I was pumping gas a lot when starting after it's already warmed up, which I had been. He said only pump it three times when it's cold (first start). On next start don't need to pump. I test drove it, tried that after shutting it off and letting it sit for 15 minutes, and although it cranked a bit, it started without pumping. Could it be as simple as having been flooding it all along? I had been giving it a lot of gas all those times when I couldn't get it started.
 
If you have the problem again push down on gas pedal and hold it to the floor, turn the key, If flooding is the problem it should now start.
 
stubbie said:
If you have the problem again push down on gas pedal and hold it to the floor, turn the key, If flooding is the problem it should now start.
Click to expand...

Ok, thanks. Unrelated, the temp gauge barely reaches normal range. I've read some posts about others with same finding. Is this a common gauge issue or is it really running cold all the time? Wondering if I should replace thermostat.
 
Ask your mechanic if he has an infared gun. That's what I used to calibrate my gauge but its easy to tell if the thermostat works with it. A cruder but effective way also works. Start it cold and keep checking the upper hose. It should stay very cool till the stat opens. When it opens it will get hot fast (then see where the gauge is). Most stats fail by internally leaking so if it is bad the upper hose will gradually get warm instead of all at once. My 65 has a calibration hole under the gauge, I'm not sure about the bullet birds. See if your mechanic is comfortable calibrating your gauge.
 
Quick mention though. If you do a thermostat, 195 deg always preferable for mileage and engine wear BUT if you put a 180 stat in, it aids in the starting thing between short trips (gas doesnt boil off as easy if you keep the underhood temps down). Your climate and use of the car is also a deciding factor in thermostat temp.
 

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