Fuel caps for Post-War Champs

[RRHaldeman]

I learned something today and thought I'd share it.

I'm renovating a 1947 7AC, converting it to a 7AC CONV with a C85 and the O-200 conversion. I needed a new fuel cap for the stock header tank. Bought a vented cap at Wag-Aero expecting it would work. I put a new collar around the filler tube and when I tried to put on the vented Wag-Aero cap, and tighten the cap, it pressed down on the new collar so that the venting would not work. (The venting tubes are on the sides of the cap but at the bottom).

I checked with American Champion in Rochester, WI and the parts department read off the dimensions of the gas cap they have. From the description, it was identical to the Wag-Aero cap, but, being close by, I flew in and checked it out. Lo and behold, the American Champion fuel cap is vented on the sides of the cap but at the TOP. Made a big difference because if I tighten the cap down onto the collar, the cap will still vent as the venting holes are on the top of the sides, not the bottom of the sides.

[Paul Agaliotis]

Wag has had this problem for many years. The grommet they use for the filler neck is wrong and blocks the venting of the caps. I believe there is a Service Bulletin that covers this problem.
Paul

[MikeB]

I ran into the same problem with my Wag Aero wing tank kit. The tank grommets are so thick you can hardly push the fuel cap on and lock it which, of course, blocks the fuel vent. There is a John Deere grommet that will fit but I don't have the part number anymore. Also (so I've been told ) a FAA certified toilet tank seal will also work as a grommet. Just be careful not to 'flush your tanks'.
In my case, I intend to vent the wing tanks with a vent tube brazed to the cap so it's not an issue.

Many years ago a friend and I were flying the club Champ which had a recent annual. We had made several takeoffs and landings, etc. and started rolling down the runway when the engine RPM died. I took the fuel cap off to look at the fuel level and 'woof' there was a suction into the tank. Apparently the IA or someone had made a new cap gasket and covered the cap vent holes. It was a darn good thing we weren't 25 feet in the air heading for the highline wires when it happened.

MikeB

[rkittine]

The cap that I have on my main tank seems to have a collar brazed around it to make it higher. Works fine that way, but since I bought the plane with it that way, I do not know who did it or how.

I did have a lot of crazy problems with my wing tank until I learned how the system works on the older models. Mine is a converted 7CCM and the Cap does not need to be vented as the tank is, but that was still an issue, so I brazed a vent on the cap that points into the wind and it now drains fine. I had the most problems initially after installign Vortex Generators on the wings that changed the ariflow over the then vented cap on the wing tank.

[Dennis]

Here is a picture of the grommet supplied by Wag verses the John Deere grommet. The John Deere part # is "R82873". The price is about $15 give or take. For use on the wing tanks, I used a razor blade to trim off the lower part at the grove where it would go under a metal skin. It is a better looking and fits better. Dennis

[RRHaldeman]

I've got BOTH of the grommets shown in the photos that Dennis posted. I shaved some off the top of the grommet but that still did not give me enough room to use the Wag-Aero cap; thus, my delight when I found the American Champion vented at the top and will work.

I also have two aux wing tanks and have the vented caps with the brazed tube heading into the wind.

My project plane should be flying for the first time next week! Put the wings on today!