The International Cessna^® 170 Association

Coming back from Reklaw this weekend I had 3.3 hours total on my fuel tanks. I checked my fuel stick and got about 4 gallons usable in each tank. I am not sure that I believe this. I am going to drain my tanks via the gascolator while in the three point attitude and see how much I get. To my way of thinking this is the critical combination of attitude vs. quantity. From what you said, George, and from what I can see in the parts manual (and from what I remember when I had my tanks out) the fuel drains to the engine at about the midpoint (trailing edge up to the leading edge). This should leave quiet a bit of fuel in the rear of the tank while in the three point attitude. I have never been very confident in fuel quantity after the three hour point, and I don't care to try that little trick where you take off and fly until flameout.
David

"Useable" fuel is fuel that can be utilized in all normal flight attitudes. "Unuseable" fuel is that left in the tanks after all the "useable" fuel is exhausted.
The reason the useable fuel in this airplane is 37 gals while the total capacity is 42 gals is due to that fact of where the fuel line draws fuel from the tank. In extreme nose up or nose down attitudes not all the fuel will draw from the tank. The same holds true in a bank. If the left tank is empty and the right tank is low and the airplane banks right, especially if the turn is uncoordinated, it's possible to have the engine quit inflight.
I usually plan to land with an hour's fuel onboard (about 8 gals.) I never want to land with less than 30 minutes, and even then only in daytime VFR. .Not saying I haven't,...just saying I don't want to.
(You guys are going to love the rest of this story. When I left Reklaw I hopped over to Ol' Gar's place for lunch. I'd forgotten that ARDave had gotten 5 gals of gas from me earlier. I'd hoped to have him indebted to me, but he's as hard-headed as I am and forced me to accept payment for it...and too much at that! Anyway....
After lunch, I dipped my tanks and found I had 5 gals in my right and only wetted the bottom of my modified FuelHawk tube in my left. This meant I had only unuseable fuel in my left, 5 gals useable in my right, and the closest fuel was Center, TX about 30 minutes away.
Ol' Gar had the biggest, stupidest, toothiest grin on his face as he watched me pour in 5 gals of his sorry mogas in my left tank. I'm only telling all you guys this in order to steal his "blackmail' thunder.)