Switching fuel tanks in route?

[GAHorn]

Actually, I have some lack of understanding how a vent line which is vented centrally (as our goosenecks are) can allow any crossfeed transfer at all, even with a vented cap on only one side. The most plausible explanation in my own opinion is aircraft rigging, p-factor effects, and actual plumbing routing. (I'm not altogether unconvinced that once the right side begins it's superior flow that it continues to have the advantage for quite some time. The gascolator is actually slightly on the right side and may have some mystical effect as yet unrealized. And don't forget "coriollis effect" in the Northern Hemisphere. Do our Aussie friends have their left tanks feed faster? )
My system behaves just like Bruces, and I find my right tank takes on more fuel at refueling than my left. About 1/4 more.
At any rate, the CPA's explanations are the best I've ever read, so I passed them on. Finally, their comment that this phenomenon is unimportant is quite valid in my opinion. I've run my airplane all the way down to fumes on Both and was able to access all the useable fuel and maybe even some of the unuseable fuel as well. (All deliberately, of course, in the interest of research. )
I like JJH55's suggestion about using the key on the selector as a reminder.

[flyguy]

I kinda hate to add more BS to the already confusing plethora of "bogus information"* I may have already posted but when I only had two OEM fuel caps on my '52B, I never had any problems with uneven amounts of fuel being used fron the tanks. And I did not have fuel streaks down the back of the fuselage from some unknown cause after installing the $50.00 per "vented" caps.

Funny how the EXPERTS" can make up stuff to make our lives safer and it turns out to be a means to justify their jobs. On top of that, it usually costs the poor airplane owner big bucks for useless modifications. Many times other problems arise from forcing us to rely on their expertise and "giving" it to us in the form of "REGULATIONS" instead of asking US for some real input!

*OLE GAR MADE ME DO IT!

[scott]

I made a dipstick for my aircraft out of clear acrilic hollow tubing. (they have it at spruce) It was a huge pain draining all the fuel then adding 2.5 gallons at a time and marking the stick. I was thinking what a stupid idea, I should have bought one.
A week later a friend gave me one from Sporty's for my model of aircraft
I checked it against my homade one. It was not near as accurate and it also read more fuel than was actually in the tank, by about 1/2 gallon.
Moral of the story is the store bought ones do not account for the the gear leg sag from all the Navy landings I make.
Thus the homade ones are better.

[wa4jr]

I've finally reached the bottom of this thread and am ready for a BREW. I look at the C-170 fuel system schematic, and wonder how such a simple fuel system can be the source of so many different viewpoints and "problems". I wonder what would happen if our fuel system were a tad more complicated with perhaps one more fuel valve controlling an AUX tank...or had a Piper Aztec type of fuel system Good entertainment though...I like to see just how many different ways this simple fuel system can be operated. Seems a lot of folks have a heavy left wing as I do. I am going to check the concentric bolts and rigging for this wing at annual to see what I can do to pick it up other than burn fuel from the left tank...which helps but still doesn't balance my aircraft completely.

[rudymantel]

I have a Javelin aux tank- 18 gallons under the baggage compartment- which I use on long flights only.
The procedure is to run out of the right tank, then switch to the left and turn on the electric transfer pump which transfers fuel to the right tank. Then turn off the transfer pump before switching back to the right tank or to both. With all that fuel the airplane has a longer endurance than I do but it's nice to have a generous reserve.

Unless I use the Javelin I just leave the selector on both. It doesn't bother me if the feed is a little uneven.

For dipping the tanks I use a 172 hollow tube dipstick calibrated to 20 gallons. It always indicates two or so gallons less than actual, so it's error is on the safe side. FWIW,
Rudy