I bought a back plate from Curtis Shipp for my OS 25 (tossed the plastic part in the trash).  There was no gasket on the plastic back plate, should there be one on the metal plate?

James

Yep.

Bill

          I have a question for those who purchased one of the backplates Curtiss made. Does the backplate protrude into the case the same distance as the plastic one . I ask this question based on a problem I recently encountered. I have a LA .25 on a arf Flite Streak. I guess you can say this is like peanut butter and jelly they just go together. I installed a FP.25 backplate which was new that I owned for years. I encountered some funny runs recently mainly due to a inferior tank I purchased. I've since opened and replumbed the tank which turned out very successful. The engine though starts off fairly lean than it appears to go rich followed by what sounds like its sagging. I asked myself why would it just start slowing. I put the plane away for a few weeks and when I picked it up it was hard to turn over. I wasn't sure what this was about so I took the head off. The engine looked as new as the day it was made so I reassembled and it flipped fine so I flew it again. The engine sagged once again and while it was hot it appeared to have a slight bind in it while turning it through its revolutions. I took it completely apart thinking that just maybe the metal FP backplate might be into the case too far. It did have some slight rub marks but nothing I haven't already seen in other engines. While holding the engine in hand and turning it over without the backplate on, I noticed it got tight as it was nearing top dead. I then noticed the rod was half on the crank pin when this happened. I pushed it all the way on and it turned over smooth as ever. I then pulled it back the rod and sure enough the bind appeared again. I pulled it back as far as I could then used the backplate to push it forward only to notice the rod could actually be moved even more onto the crankpin. I no longer have a plastic backplate to compare the FP backplate to. My guess is though the plastic one goes into the case a bit deeper. I'm curious to know if anyone has ever compared the two back to back. I didn't have a leak when I switched to the Fp backplate. In fact I own 6 LA engines all but this one with stock backplates and none of them has leaked. I only switched due to the consensus of flyers just saying to do so. I do keep a close eye on them though. Ken

I see that RSM Distribution now sells gaskets for a variety of engines, including those under discussion. Might be worth a look, Eric Rule at RSM is very helpful!