Hey guys
I am trying to install a OS .46LA into my sig 4 star 40. Sig says to use 6/32 screws but the engine hole is 4/40. Should i drill them out or are the 4/40 gonna hold up?

thanks for the help

Use the 4-40 screws, don't drill out the engine lugs. These screws are fine for a 46 engine.

G'day Mate,
4, 4-40 UNC bolts & nylock nuts should be plenty to hold it on, although an OS 46AX, has holes just right for 6-32 bolts, I have no 46LA's so I don't know what size holes are in the engine mounts, but I'm sure 4-40 would be OK, but you can drill them out if you feel the need.
OS recommend 3 to 3.5mm bolts. 3mm is pretty close to 1/8"

Here's another tip if you've never run an OS LA series motor before. For a significant power boost, remove the baffle from the muffler. To do this, unscrew the bolt that runs front to back through the muffler. The baffle is the cone shaped device inside. Take it out and reassemble.

It will make it a little louder (not much), but the power increase is tremendous. I was at the field a few weeks ago and someone was making a maiden with a .25 LA that would barely get the plane off the ground. I suggested removing the baffle. For comparison purposes, he tached it before and after. He gained 1200 RPM!

-Scott

Great info guys. I will also try the muffler mod after i break it in.
thanks

Forgot to mention, when you remove the baffle, you will also have to adjust the needle valve. I assume that is obvious.

-Scott