Vapor lock during parades

CalMI

CalMI

Member
My 36 does not like parades. Today for the third time it quit again part way into the parade route. Ambiant 65 degrees. I kept the flattie running by holding my momentary on switch on to run the electric fuel pump. I have no problem running down the road but if I stop and let it idle for 5 minutes it quits and it won't start until it cools down. and by the way I have checked for spark and have a strong spark.
I need help! My wife is threatening to not ride with me again.
I first thought that the problem may be the fuel lines picking up heat under the hood but now I am thinking that the fuel line may be picking up heat from the left side exhaust pipe. The fuel line follows the exhaust the whole length.
I do have a fuel line insulator sock from front to back but I am suspecting that it may not be enough to keep heat from getting to the fuel. My question is where are you all with dual exhaust running your fuel line. should I reroute the line or I'm thinking I could wrap the exhaust pipe with insulating wrap.
Thanks for your help,
Cal
 
My '36 does not like parades either. For a different reason, my car starts spewing a bluish smoke out the exhaust during parades until I pull off and begin driving at normal speeds. As far as for vapor lock, I have not experienced it (yet) although I try to use only pure, nonoxygenated gasoline and have wrapped my dual exhaust pipes from the manifold to the muffler. A check with an infrared temp sensor shows less heat from the wrapped pipes but still very hot. Have you checked the fuel pressure coming from your mechanical pump? How about trying a different mechanical pump? they are inexpensive and might be an easy experiment. Also, I am wondering if your fuel line "sock" is keeping heat in!
 
My `35 does not like parades either. No vapor lock, runs perfect but heat gauge steadily climbs. Installed external electric fan, slowed down the heat but still creeps up. Has Skips pumps, new radiator, Skip's pressure relief valve, cleaned engine with vinegar, has wettter water, Barrs Stop Leak, anti-freeze and checked negative for compression leak. No heat problems on the road with ambient temperature in the mid 90's and high humidty. Just does not like parades or long traffic lights on hot days. But I love the old car, runs excellent and a blast to drive with the top down and the Smitty's barking.

Shadetree
 
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vapor lock is the fuel in the line turnig to a vapor before it gets to the fuel pump causing the pump to lose it prime, fuel pumps dont like to suck vapors, when it starts acting up run the electric pump, it might not even be the pump, heat from the engine manifold might be boiling the fuel out of the carb, if your intake manifold has the exhaust cross over ports in the intake manifold , plug them, the crossover port will be just behind the carb mounting base, install a 1/2" fiber spacer under the carb, check fuel pump for pressure it should be around 2 1/2#, get a good fuel pump new or rebuilt with american parts, ken ct is an excellent source for that, nothing but amercan parts, hes on here a lot, route the fuel lines as far away from the exhaust manifold as you can,
 
Shadetree, I have heard of guys putting a length of copper tube at the top the radiator fins,front side, with small holes in it. Plug one end and run the other to a windshield washer pump with a supply of water. As soon as the temp starts rising, turn on the pump and viola! instant air conditioning for your engine.
This is for parades only, and you can take it off after your done.
 
Ralph Moore said:
Shadetree, I have heard of guys putting a length of copper tube at the top the radiator fins,front side, with small holes in it. Plug one end and run the other to a windshield washer pump with a supply of water. As soon as the temp starts rising, turn on the pump and viola! instant air conditioning for your engine.
This is for parades only, and you can take it off after your done.
Click to expand...

Ralph,
That sounds like a great idea. I know this is a common problem with our old Fords and I have tried to think of remedies. The evaporating water spray would do it I am sure. Best I just keep it out of parades.

Thanks,
Shadetree
 
Well at least my engine is not over heating. The temp gauge stays in the middle of the range. I like the idea of checking the fuel pressure from the pump. I may also lengthen the pump push rod. Good ideas there.
my wife says just don't drive it in parades. Well I still would like to make it more reliable.
It sounds like I may need to try a multi-pronged approach.
I really think the heat is coming from the exhaust pipe and I need to correct that problem. I have two 97s on an Edelbrock manifold. I don't know if that is a problem or not but at least the carbs are a ways from the engine heat so I don't think that carb spacers would make a difference.
 
I had the same problem on my 42 Merc. Installed a modern coil with built in resistor several years ago, no problems since.
 
Ralph Moore said:
BTW beautiful 35.
Click to expand...

What this old rag? C'mon!

Thanks,
Shadetree

13.jpg
 
That "old rag" of SHADETREE's might look a little strange, with it's spotted paint-job, but it has about the best original sheet-metal, that you will ever find in an old flathead Ford.
MIKE :)
 
It's the gas! On hot TN summer days, my 32's carb will actually boil the gas. I put a pusher pump close to the tank and when those symptoms start, give it a burst with the elec pump then turn it off. Had to put diesel, 1 gal to a tank of gas in my old Packard the stop it form vapor locking.
 
Conduct pressure and vaccum tests on the fuel pump while it mounted on the engine, looking for bad valves or punctured diaphram. If all okay, I use RTV cement inplace of the gasket under the fuel pump stand. Appears to me that you stated the solution - run electric fuel pump mounted at the tank. Parades are tough - a lot of heat buildup - not like sitting a taffic light of a few minutes. I would run the electric pump continuously assuming the mechanical pump does not have a defective diaphram.

Best wishes,

Bill OH
 
Best way to solve fuel vapor lock- regulator and a return line. Get a small regulator, hide it well, 1/4 line for return. Can be done neat and sanitary most cars. You'll need to add a tank nipple to receive the return fuel.
The constant circulation keeps air out, and fuel cool.
 
Check your fuel line from the engine to the tank is not to close to the exhaust had same problem on my 48 where the pipe comes up from the chassis to the pump the exhaust is near by. End using a heat shield to find the problem then just re routed the pipe.
 
In the flathead era the cars were new. Parades were full of horse drawn stuff from their yesteryear. From my memory, I know we didn't let the cars set and run at idle too long back then either. The old model As,Bs, & Ts could idle quite a while but the V8s have a fair amount of exhaust gas going through water jacketed areas. This transfers a lot of heat into the block if the motor isn't up to speed for the pumps to carry it away.
 
Left exhaust pipe running the length of the gas line doesn't help , todays crappy gas doesn't help any either, but I would put my money into a good rebuilt coil from Skips and I would think that most of the "vapor lock" problems would go away.
 
A coil will not fix vapor lock, that's wishful thinking. The problem is today's gas and it gets worse every year. The vapor pressure of fuel nowadays is matched to fuel injection systems and the powers that be act like carbureted engines don't even exist anymore. Back in the day, most if not all vehicles had provisions to actually HEAT the fuel to get it to vaporize better, such as carbs intentionally close to exhaust manifolds, coolant circulated through intake manifolds, etc., all of which contribute to vapor lock problems today.
 
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