Im trying to install my engine (OS 46LA) and mounts to the firewall and the directions say to have the prop nut washer 4-3/8 inches from the firewall. At very best I get 4-1/8 inches, is this going to be a problem? I was thinking of using some scrap ply left over from the kit to add 1/8" or should I just leave it? Anyone have a problem with this engine fitting right?

thanks, chris

Chris,

I cant figure how you are 1/4" short.

I didn't have a problem fitting my OS 46 LA, so maybee you have to get longer engine mounts.

I don'y know how critical the measurements are.

Anyway Chris, I cant see any problems with your suggestion of adding another 1/4" ply to the firewall.

Good luck witk it Chris, the LT 40 flies great. You will love this very forgiving trainer.

I have changed my engine now to a 49 MVVS. Man, does she honk.

Sidekick.

I've got the ARF version and I'm now on my 3rd engine.....
I'm not sure if I measured it when I first put the Irvine 39 in it, but I don't think I bothered when I fitted the OS46FX and as for the OS FS70 I recently put in I just put it as close to the firewall as possible.

With an uncowled engine, unless there are balance problems and you have a fair amount of leeway, I'd just mount it so you have sufficient clearance in front of the firewall to route the fuel tubing and you have around 1/4" clearance in front of the side cheeks....

I guess as engine sizes vary, SIG just choose to specify this as distance from firewall to prop. This is not critical.

Chris,

I also have an LT 40 and my 40 LA fit with the motor mount in the kit, it was out toward the end of the mount but I felt it would be fine. My thought is maybe they put a mount from the LT 25 in with your kit by mistake. Go to www.sigmfg.com and go to contact us,and give them a call and they will be more than willing to help. I've contacted Sig 2 times with minor problems and questions and both times they have been eager to help. I've got over 60 flights on my LT 40 without a problem, its a great plane. I'm almost finished with my somethin extra hope its as good or better.

P.S. I strongly suggest using their #64 rubber bands. If you can't find them at your local hobby shop, you can get them directly from sig.

I built an LT-40 from a kit and fitted it with an O.S. 46LA also. The motor mount supplied in the kit was ample long enough to get the prop washer 4 3/8" away from the firewall, so my guess is that they've supplied you with a motor mount that's a little too short - maybe one from the LT-25 kit. Drop SIG a note explaining your problem and I'm sure they'll supply you with the correct part.

Cheers,
Neil.

I wouldn't worry bout it myself as long as it clears the nose of the plane. In fact I would wait to drill the holes in your mount until you try to balance the plane. You might be able to gain a little moving it back and forth. If it balances and clears it's perfect!