Refurbishing Carb Heat Box

[dguthriem]

I'm stripping and painting a carb heat box I bought off FB Marketplace. It is in very good condition but missing the four nut plates that are riveted to the face to hold the Air filter frame.

Can anyone point me to a source for these? My current Carb-heat box has #14 tinnerman-style nut plates installed but the largest size Spruce and everyone else has is a #8.

Do people generally change these out to traditional machine-screw lock-nut plates and is it acceptable to do so? It appears they allow attachment of the air filter frame with 1/4" sheet metal screws or (if I change them out) 1/4" machine screws.

Thanks,
Dan

[gfeher]

I have a Brackett air filter on my engine and the filter housing is attached to the air box with machine screws and AN-365 fiber lock nuts. No nut plates. That might be why yours doesn’t have nut plates. The Brackett was on my engine when I bought my plane over 10 years ago and I’ve never had a problem with that setup. So I haven’t messed with it. I’ve never had a problem with the machine screw and fiber lock nut combination.

[dguthriem]

Thanks @gfeher, I think I'll have to go this route (machine screws and lock nuts) or remove and reinstall the "tinnerman-style" two lug nut plates from my old airbox. I like the idea of machine screws and lock-nut nut-plates. I'll check with the A&P and see what they want to do.