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pressure relieve valve  Rating:  Rating
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 Posted: 03-31-2013 06:49 pm
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jdodds56
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I have read several topics on the fuel system/gas tanks and just get more confused. I hope somewhere out there is help.

I have a 1974 J-H. Manufactured in Dec 1973. Everything I have looked at shows the pressure relieve valve on top of the tank, and under it there are two connectors. My old tank, which was out of the car when I got it, only has one. Any J-H historians out there that can explain to me what was added to later J-H's that required two? I am having a tank made and want to know if I should have it made with two. If there is something I should be concerned about adding later to the fuel system.

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 Posted: 04-02-2013 03:19 pm
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Jensen Healey
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There is a return line from the fuel pump that prevents siphoning when the car is parked with the nose downhill. The other is the vent tube that connects to the carbon canister.
http://deltamotorsports.com/cgi-bin/bigimage.pl?site+DMSCAT+img+/products/Images/FuelSystemPlate.gif

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 Posted: 04-02-2013 03:58 pm
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jdodds56
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Then I assume it would be wise of me to add the return line to prevent the siphoning. Thanks

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 Posted: 04-02-2013 06:47 pm
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Jensen Healey
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Please read Jody Kerr's excellent article on installing a fuel tank.
http://www.theymightberacing.com/Projects/FrameOff/JH74G/FuelSystem.aspx
There is a check valve in the return line that makes the seemingly impossible system work.

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 Posted: 04-02-2013 10:28 pm
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Jim Ketcham
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Do not forget that there is a check valve in the anti-syphon line. Jensen placed it completely inside the hose so most got thrown out with the old hoses.

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 Posted: 04-03-2013 03:41 am
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jdodds56
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Seeing how I am manufacturing the anti-siphon connection as an after market part for my car, how does one go about finding the right size check valve?

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 Posted: 04-03-2013 07:42 pm
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Jensen Healey
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The info is in the article at Jody Kerr's site. Basically it's a metal plug with a .046 hole drilled through it.

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 Posted: 04-03-2013 10:19 pm
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jdodds56
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Thank you the info. It makes sense to me now after all the reading. Can't wait to get the tank done and in. I'm sure I'll have more questions in the near future.

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 Posted: 04-04-2013 01:02 am
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Jim Ketcham
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You can buy fuel check valves 1/4 or 5/16" on eBay or Amazon. The lines on both my cars had tiny check valves installed in the return lines. These are actual One way valves, not just an orifice as described in Jody Kerr's article. These were fairly common in many cars and are still available.

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