Anyone tried this? Post shut down cooling.

[Old Henry]

My idea comes in part from the '79 Datsun 280ZX I had for many years. It was a sports car with an in line 6 cylinder 3 liter fuel injected engine. After the engine was shut off a centrifugal fan would come on down on one side of the engine and blow air through ducts up over the engine onto the fuel injectors to cool them. Don't know why but it did. That's what my carb needs after shut down on a hot day.

 

[BILL WZOREK]

Henry: You say you drive a short distance / come back to car and smell gas I think you should look for a gas leak as oldford2 mentioned.If you drive the car a short distance and it gets hot enough to BOIL the gas.
Did you have this problem before you took the engine out for the work done on it.
After all the gas is the same then as it is now.
And you never mentioned it before.
Maybe removing parts & renstalling them some thing got moved around, Carb Gasket / Fuel line comes to mind. Fuel pump / Gasket JUST SOME THOUGHTS

 

[Old Henry]

Professor,
What is the air temperature in your engine bay with the hood closed? Since this gas smell problem has not been supported by others who have a similar problem. I suspect you may have a gas leak in the under hood fuel supply lines/pump.
You feel pretty strong that an insulator between the carb and manifold is a waste of time. Have you used a laser gun to check temp with and without an insulator? This should be done before you condemn Bob Shewman's phenolic insulator.
John

Haven't figured out a way to measure the air temperature under the hood without lifting the hood to test it which would immediately lower the temperature and not give an accurate reading with it closed. I'm still working on that one.

Haven't measured the difference between the temperatures of the carb and manifold on each side of the spacer. I expect the spacer does some good but not in my situation where the heat is coming from the entire engine heating the air under the hood.

 

[Old Henry]

Henry: You say you drive a short distance / come back to car and smell gas I think you should look for a gas leak as oldford2 mentioned.If you drive the car a short distance and it gets hot enough to BOIL the gas.
Did you have this problem before you took the engine out for the work done on it.
After all the gas is the same then as it is now.
And you never mentioned it before.
Maybe removing parts & renstalling them some thing got moved around, Carb Gasket / Fuel line comes to mind. Fuel pump / Gasket JUST SOME THOUGHTS

Professor,
Since this gas smell problem has not been supported by others who have a similar problem. I suspect you may have a gas leak in the under hood fuel supply lines/pump. John

I've had this smell problem for a couple of years. When it first started I searched long and hard for any kind of leak and found none. Then I took off the air cleaner and looked down into the carburetor and could see and hear the gas boiling out of the carb into the throat. If it was a leak it would not be solved by opening my hood which it is.

 

[51 MERC-CT]

Haven't figured out a way to measure the air temperature under the hood without lifting the hood to test it which would immediately lower the temperature and not give an accurate reading with it closed. I'm still working on that one.

Haven't measured the difference between the temperatures of the carb and manifold on each side of the spacer. I expect the spacer does some good but not in my situation where the heat is coming from the entire engine heating the air under the hood.

Get yourself one or two digital indoor/outdoor thermometers with the long wired temp. bulb. you can take temp. readings where ever you want with the hood closed. Was able to get readings for my cold air induction modification.
See here--
http://www.fordbarn.com/forum/showthread.php?t=111242

 

[Old Henry]

Get yourself one or two digital indoor/outdoor thermometers with the long wired temp. bulb. you can take temp. readings where ever you want with the hood closed. Was able to get readings for my cold air induction modification.
See here--
http://www.fordbarn.com/forum/showthread.php?t=111242

I thought of doing that since I have the wireless indoor/outdoor thermometers but they only read up to 151°. I'm pretty sure my engine compartment gets way above that. It's gotta to boil the gas in the carb. I'll give it a try and see.

 

[GaryTx]

Old Henry, My thoughts are you are masking the real problem with a fan. I would send the carb out to a professional on the Ford Barn. The worst part is Old Henry will sound like an import with the fan running with the ignition off....lol

 

[ford38v8]

Henry, if, as you say, your bowl vent is external, not internal, then that in itself is part of the problem. Your 1947 Ford should have a Model 59 carbuetor, which vents internally. Whatever carb you have now is incorrect for your car. Get the correct carburetor for your car, take two aspirins and call the office in the morning

 

[Old Henry]

Henry, if, as you say, your bowl vent is external, not internal, then that in itself is part of the problem. Your 1947 Ford should have a Model 59 carbuetor, which vents internally. Whatever carb you have now is incorrect for your car. Get the correct carburetor for your car, take two aspirins and call the office in the morning

You are right about internal venting. I was judging from the diagram I posted instead of going out and looking at the carb. I went out and looked and it does have the vent tube opening right in the middle of the top of the throat and says Ford 59 on it which is the same as the Holley 94. I corrected my previous post. Sorry about the mistake. As hard as I try I don't seem to be able to always avoid those. Good there's usually someone that can correct me.

 

[Pete]

Henry, if, as you say, your bowl vent is external, not internal, then that in itself is part of the problem. Your 1947 Ford should have a Model 59 carbuetor, which vents internally. Whatever carb you have now is incorrect for your car. Get the correct carburetor for your car, take two aspirins and call the office in the morning

I was thinking that also.
The problem is that the gas is not actually boiling. It is pushing past the float valve after the engine is off and overflowing into the manifold.
A Viton tip float valve MAY cure it but not always.
There are Mickey Mouse ways to bleed off this residual pressure after shutdown but consider this, with all original type parts, this problem was non existent.

 

[Old Henry]

The problem is that the gas is not actually boiling. It is pushing past the float valve after the engine is off and overflowing into the manifold.

That doesn't make any sense to me. Even if the fuel in the bowl could create some kind of pressure in the bowl, which it shouldn't be able to since the bowl chamber is vented, and pushed past the float valve it wouldn't flow into the manifold, it would flow back through the fuel line toward the fuel pump and gas tank. Also, it doesn't make sense because the fuel would be pushing the same direction that the float valve pushes to close the valve thereby causing it to close tighter rather than push it open. If my float needle valve was defective it would not be closing to stop fuel coming into the bowl against the pressure of the fuel pump and I'd be flooding all the time.

 

[Old Henry]

Although I've heard about this problem from a few it has been pretty rare. I'm thinking that some of the problem could very well be the elevation that I live and drive (5,000+ ft.) that allows the gas to boil at a lower temperature than most of the rest of you.

 

[Old Henry]

Old Henry, My thoughts are you are masking the real problem with a fan. I would send the carb out to a professional on the Ford Barn. The worst part is Old Henry will sound like an import with the fan running with the ignition off....lol

I'm listening for your ideas about what might be wrong with my carburetor that's causing my problem. What are your ideas?

I agree with you that the sound of the fan running may be as annoying as the smell of gasoline (other than hopefully the sound would stop sooner than the smell would) and, at an estimate of $130.00 for the fan and thermostat switch that may or may not solve the problem and may kill my battery so we would then be pushing to start (way more embarrassing) I'll have to really be convinced the smell is worse than the sound.

 

[Ross F-1]

My O/T car is setup this way from the factory; basically, the fans are powered and controlled independently of whether the engine is running. Very common on european cars. It's to prevent varnishing the injectors.

I put two of the Vintage Speed extra-thick carb-to-manifold gaskets under the carb for the summer, and it has all but stopped the boil-off smell. It will still evaporate off between runs (say, over a period of a week) because my garage is hot and I'm at similar altitude. But the smell isn't there, and there is no evidence of actual boiling from the bowl. In the winter I'll go back to a normal gasket to get the benefits of the heat riser.

 

[Pete]

That doesn't make any sense to me. Even if the fuel in the bowl could create some kind of pressure in the bowl, which it shouldn't be able to since the bowl chamber is vented, and pushed past the float valve it wouldn't flow into the manifold, it would flow back through the fuel line toward the fuel pump and gas tank. Also, it doesn't make sense because the fuel would be pushing the same direction that the float valve pushes to close the valve thereby causing it to close tighter rather than push it open. If my float needle valve was defective it would not be closing to stop fuel coming into the bowl against the pressure of the fuel pump and I'd be flooding all the time.

It is not the fuel in the bowl when the engine is initially shut off that causes the problem.
That normally would just sit there.
It is the residual pressure left in the fuel pump and line from the pump to the carb. The pressure pushes fuel past the float valve, overfills the float chamber and then seeps out the dump tubes into the manifold.
This is a very common problem, even with modern 4 barrel carbs.
The check valve in the pump prevents fuel from returning to the tank. It holds far better than the float valve.

 

[Vic Piano]

Maybe I'm missing something here but, it’s an old car... old cars, especially Flathead Fords emit certain aromas like the pungent bite of gas and oil... its part of their persona... You know the old saying, "if there's no oil under it... there's no oil in it", well, the same holds true for gas... if you can't smell it... its empty... Sorry Prof. I couldn't help myself... at least you didn't get Vapor Lock... LOL

 

[Old Henry]

Maybe I'm missing something here but, it’s an old car... old cars, especially Flathead Fords emit certain aromas like the pungent bite of gas and oil... its part of their persona... You know the old saying, "if there's no oil under it... there's no oil in it", well, the same holds true for gas... if you can't smell it... its empty... Sorry Prof. I couldn't help myself... at least you didn't get Vapor Lock... LOL

I've been using those "one liners" for some time now to excuse Old Henry's body odors. Just thought I might try to reduce them if possible.

Oh, I get Vapor Lock all right. That's an easy quick fix with the backup electric fuel pump.

 

[Old Henry]

It is not the fuel in the bowl when the engine is initially shut off that causes the problem.
That normally would just sit there.
It is the residual pressure left in the fuel pump and line from the pump to the carb. The pressure pushes fuel past the float valve, overfills the float chamber and then seeps out the dump tubes into the manifold.
This is a very common problem, even with modern 4 barrel carbs.
The check valve in the pump prevents fuel from returning to the tank. It holds far better than the float valve.

Ah. . . Now I see your point. Not sure how I'd diagnose that problem. It actually looks like the same problem - heat in the engine compartment that needs reduced. How would I tell the difference between the two when both cause gas to push into the carb throat and smell?

 

[Pete]

Ah. . . Now I see your point. Not sure how I'd diagnose that problem. It actually looks like the same problem - heat in the engine compartment that needs reduced. How would I tell the difference between the two when both cause gas to push into the carb throat and smell?

The heat has nothing to do with this other than aggravating the smell.
When you pull up and shut down hot, Put a rag around the fuel line connection at the fuel pump to soak up fuel and SLOWLY unscrew the fitting nut.
This will immediately release the residual pressure. Retighten the nut
and observe if there is any fuel leaking down the carb and smelling.

What it "boils" down to is if the float valve doesn't leak, there is no problem.

 

[ford38v8]

...A Viton tip float valve MAY cure it but not always.
...

Pete, I'm surprised that nobody else caught this before now... DO NOT use a Viton float valve.
The new gas makes them swell and stick. Use only the steel on steel valves.