Poll-170B Fuel Valve roll-pin diameter?

[Karl Towle]

On behalf of our friends at McFarlane, I'd like to poll the members who've rebuilt their 170B fuel selector valves. They (and I) would like to know what diameter roll-pin you found connecting the ball & spring housing to the shaft of your valve. Here is the history:

Our C170 IPC shows a fuel valve part number 0513120-5 for the C170B. The IPC also lists 52-028-125-0500 as the correct roll pin for this valve. This part number crosses to NAS561P4-8. Both of these parts are 1/8" (0.125") diameter, 1/2" long roll pins.

When I ordered my FSO-KT-17 rebuild kit from McFarlane, it showed up with a 3/32" (0.09375") roll pin. Needless to say, I thought they had incorrectly built their kits. However, in discussing this issue with them, I was told this same fuel valve, is shown in the IPCs for other Cessna models with a NAS561P3-8 roll-pin, which is 3/32" in diameter. While I was not able to personally verify this, I did find a depiction showing 0513120-6 and 0513120-8 fuel valves using the smaller roll-pin. All of these dash numbered valves (and others) are serviced with the same kit.

So, please chime in. we need to know if some previous mechanic over-sized my roll pin trying to make it match the IPC, or are most 170B owners finding 1/8" roll-pins already installed as I did. Depending on which way this goes, we could be onto another IPC error associated with this particular assembly.

Finally, I'll pass along a caution from McFarlane: "Examine the shafts and “housings” for signs of modification during valve overhaul. The shaft should have a square bottomed groove and the housing needs to fit on the shaft in a manner that correctly orientates the ball to the detent plate."

[oilleak]

Just rebuilt my fuel valve with the kit from McFarlane. The roll pin in my fuel valve was also 1/8" in diameter.