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Model Engine Gas Tanks and Caps

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  • Model Engine Gas Tanks and Caps

    This is something that I don't see much about, but it is integral to almost every model internal combustion engine. I build my own gas tanks, generally from 1 1/2" schedule 40 steel pipe. a clean-up pass on the outer diameter, and ends either from steel silver soldered into place, or from aluminum attached with J.B.Weld. (No, Naptha gas doesn't soften J.B.Weld) I use a 1/2" schedule 40 pipe nipple silver soldered into place as a tank filler neck. This filler neck is approximately 1/2" inside diameter, and it lets me see how much gas I'm putting into the tank without messy and dangerous overflows.--I buy a standard 1/2" pipe cap and modify it slightly by machining the outside diameter and drilling a 1 mm "breather hole" in it for use as a gas cap. These caps are uglier than sin in their "as cast" original shape. Turning the outer diameter and sometimes knurling it improves the look, but not much. Today I took one of these "modified" gas caps and modified it even more by turning the outer diameter to as much smaller as I could get without breaking thru the internal threads, turning off the raised section, and knurling the outer diameter. It improves the look. All my previous gas tanks had a lot more of the filler neck stuck up above the tank than was necessary. Tomorrow I will finish the gas tank on my current vertical i.c. engine project. I will have less exposed filler neck, and use the new style cap as seen in the picture. The second picture shows an existing gas tank with the "new style" gas cap on it.

    Brian Rupnow
    Design engineer
    Barrie, Ontario, Canada