gascolator test

[mulwyk]

I was setting up to test the primer system yesterday and it looked like it would be a good time to plug the gascolator ports and test it at the same time. I hooked up the test rig shown and applied 20psi air pressure and soapy water.

The primer system was fine: no air flow with the plunger in and locked, nice air flow with the plunger out, no bubbles around the fittings with the engine fitting capped.

But the gascolator! Holy crap, I had air leaks everywhere. I took the old thing apart, applied fuel-lube to the gaskets, and then re-assembled and cranked that nut on the bottom down as hard as I could. That got rid of the leaks around the glass top and bottom but the little drain valve was still pissing air. Check out the halo of bubbles around it in the photograph.

My question is this: I'd like to keep the old gascolator (I just like the looks of it, glass bowl and all, and anyway I don't want to pay up for a new one), but I'm feeling a little queezy after all the trouble it's given me. Is it possible that 20 psi was too much for the old girl? My physics is a little rusty, what would be a typical pressure at that point in the fuel system?

[1938BF50]

Re: gascolator test

1-2 psi max

[Hank Jarrett]

Re: gascolator test

Holy Crap is right! You are lucky you aren't picking glass shrapnel out of your back side! Pressure head for a gravity feed fuel system is less than a couple of pounds. I test our fuel systems with a HAND TIRE PUMP and a condom over the fuel fill.
Hank
Loosen that nut on your glass bulb too. It doesn't need to be clamped down hard. If there is a scratch on the edge of the glass you may break it when the engine vibration hits it. Just hand tighten. No more than hand tight and snug. At least your system has been proof tested!

[mulwyk]

Re: gascolator test

Yikes! I guess 20psi was a way too much pressure. And, Hank, I wouldn't be picking glass out of my back side. I did my fool test while seated on a milk crate with my face 6 inches from that glass bowl. Ouch!

I actually tried to calculate the pressure (by figuring the weight of a column of fuel one inch square by 20 inches high). I came up with 0.4 psi, but I thought I must be mistaken, that it must be much higher than that. So I just picked 20 psi 'cause it sounded about right.

Thanks guys for setting me straight. I'm lucky something didn't break. I'll be more careful in the future.

[NY86]

Re: gascolator test

0.4 is pretty close. A column of water 33 feet high makes 14.7 psi. Gas is less by about 25%. Stromberg specs the carb with a fuel column 15 (or is it 18?) inches high.

Overtightening the bale can actually distort the cover and then no amount of tightening or gasket replacement will fix it. If it leaks at hand tight, replace the gaskets!