No vapor lock for me

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Model T Ford Forum: Forum 2016: No vapor lock for me
Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Tuesday, April 26, 2016 - 02:31 am:

I actually took some time for a bit of Model T work, staying up late (now early) to install a new fuel line in my 1923 touring.


With the traditional fuel line route above the exhaust pipe into the frame rail, the line is only about 1" above the hot pipe. I prefer to go forward and under the pipe to keep it out of the rising heat.


With this arrangement the fuel line is no closer to the exhaust than 2" at the closest point.


That's right, I didn't put a shut-off valve at the carburetor. Later I'll show what I plan to do about that.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Derrick Pang on Tuesday, April 26, 2016 - 03:13 am:

Will have to do this on mine. Thanks Steve


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan B on Tuesday, April 26, 2016 - 07:46 am:

Does the gas now have to travel uphill at the portion around the hogshead?

I routed my gas line as Ford did and have no vapor lock issues.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan Treace, North FL on Tuesday, April 26, 2016 - 08:14 am:

Use the Ford route, 'cept bend the gas line under the running board brace instead of over it like Ford.

Think this gets the gas line far enough from the exhaust pipe, and also use the Ford clamp on the frame, the one fitted to the bolts and nuts of the cross shaft. Like the idea of the gas line fastened to the frame.





Ford method, over the brace, near the exhaust pipe



Modified with line going under the brace, but still using the frame clip on the gas line. The gas line is mostly flat to the carb after the drop from the sediment bulb. Haven't had issues with vapor lock.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Tuesday, April 26, 2016 - 08:28 am:

Yes, the gas has to travel uphill. It doesn't matter. Liquids seek their own level. As long as the source (tank) is higher than the destination (carburetor), the liquid will flow. Just like water in your house. It enters in an underground pipe and flows up to the faucets because the source (standpipe or water tower) is higher than the faucets.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Michael Garrison - Rice Minnesota on Tuesday, April 26, 2016 - 08:35 am:

Well yeah, and it doesn't hurt to have a submersible pump and a pressure line to push the water along.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Tuesday, April 26, 2016 - 01:42 pm:

While doing yard work today I got to thinking about this. Why is the Ford way better?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Erik Johnson on Tuesday, April 26, 2016 - 01:45 pm:

Both our '17s have their original gas lines and they are routed as they came from the factory. Never had a problem with vapor lock.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan Treace, North FL on Tuesday, April 26, 2016 - 01:56 pm:

Steve

Don't know if its 'better' ? But do know someone tested the psi from the gravity fed line from the gas tank mounted on the frame as got less than 1 psi!

So there needs to be a good amount of gasoline in the tank for a head pressure. That is what provides the push for the gas to reach the carb.
Sure the T can run out of fuel and stop, but on hill climbs up steep roads, the fuel can difficult to reach the carb.

The drop from the sediment bulb is normally enough. As long as the screen there isn't clogged. My '24 had fuel delivery issue, and found that the screen was about 2/3 clogged with fluff, think from the seat cushion too, some how it fluttered into the gas cap vent hole? Least that was my thinking :-)




Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan B on Tuesday, April 26, 2016 - 03:24 pm:

Not sure if it's a matter of it being better. The Ford way routed the fuel line using the most direct path, using the least amount of material, with no performance issues. Therefore it was engineered correctly.

But your explanation is correct. I think Bernoulli told us this.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Wednesday, April 27, 2016 - 04:08 am:

There is a difference between the original Ford exhaust pipes and what's available now. With a repro exhaust, the Ford way to route the fuel line will get very close to the exhaust, but with a correct exhaust pipe the Ford way is fine.

One thing wrong or modified often causes other modifications until everything works as planned :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Wednesday, April 27, 2016 - 07:40 am:

The frame rail route uses about 41" of tubing. Mine is 37". :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Brough on Wednesday, April 27, 2016 - 08:45 am:

On my 42 Ford GPW military jeep, the fuel line runs from a tank under the drivers seat on top of the exhaust pipe, to a fuel strainer mounted on the cowl, then from the strainer directly to the engine block with clips, around the front of the engine block to the fuel pump and then the carb.

So Ford has no major concerns about routing fuel around, over, and near hot or warm engine parts.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan B on Wednesday, April 27, 2016 - 09:00 am:

Ok you win. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Harold Schwendeman - Sumner,WA on Wednesday, April 27, 2016 - 12:23 pm:

Not sure if this makes sense or not, or if I can explain this "recollection" I have or not, but I'll try, for whatever value this might have:

Somehow or other, I recall something about the fuel line, whatever the particular route from tank to carburetor, the fuel line should have one (and only one) particular low point, making sure that the fuel line is ALL downward from the tank (potato) to the one low point, and ALL continuously downward from the carburetor to the one low point. The reason for this being that if an air bubble should occur in the line, the bubble would, of it's own accord, seek an upward route to either the tank or the carburetor. Why an air bubble might occur, I have no idea, but I know I've run across this "theory" somewhere. Anybody else ever heard this? FWIW,......harold


Top of pagePrevious messageNext messageBottom of page Link to this message  By paul iverson freeport ill. on Wednesday, April 27, 2016 - 01:27 pm:

I have had problems with small eng fuel lines that had a small dip in line until you get the air out, once the air is out it works fine, the dip may hold sediment tho


Top of pagePrevious messageNext messageBottom of page Link to this message  By Donnie Brown North Central Arkansas on Wednesday, April 27, 2016 - 04:44 pm:

Harold, you are correct about the bubble rising both ways from a single low point. From what I was taught by my mentors, the air bubble can be formed by the heating of the gas at a hot spot. If it is possible to rise to a high spot in the line, and not travel to either the carb or back to the gas tank, then that is vapor lock. Old MOPARS from the 60s era had a bad vapor lock problem. The fix usually involved re-routing the line as much as possible away from the heat source, and making the gas line with no high spots in it. I remember my dad and myself changing out the gas line on a 1969 Dodge he had back then. When it was hot (and it can get hot in southern Arkansas) the car would vapor lock. After changing out the line, it never did it again .... Just my 2 cents worth and probably overpriced again ... :-) ... Have fun and be safe.... Donnie Brown .....


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