I just purchased a 40 size trainer. Since it was used it didn't have a manual. I need to know how much throw I should have for the control surfaces. Also, I need to find the cg. I have been told to start at the spar or the thickest part of the wing. Which is the correct method? Any help with this would be appreciated.

google the manual for it. You probably can find something.

This plane, I'm guessing, is around 20 years old and i have no idea who manufactures it. The old covering was very sticky. very strong and thick. I'm almost certain it is an arf because who ever glued the two wings together glued them slightly miss aligned. It is very well constructed, light ply fuse, and 3/8 dowel push rods for the elevator and rudder. My guess is that it was made in Tiawan. So google search for a manual is impossible since I have no idea who manufactures it. The plane was previously flown and was left in a garage when the owner passed away.

If you can post a pix, maybe someone will recognize it. Otherwise, measure the chord of the wing and divide by four. That would give you a starting point for the cg. For throws, maybe 12mm up/down for ailerons, 15mm for elevator and rudder? Or you can find a similar size and type of plane and download its manual.

Something that might also help would be to know the wingspan and aileron configuration. A strip aileron can have a different throw than a barn door

If, like most trainers, it has a "Hershey Bar" wing (i.e. each wing panel is a rectangle), setting the balance point at about 25% if the wing chord should be OK. That's likely to be near or on the main spar, so setting it there should work, too. If you can post a picture and tell us the wingspan, we can recommend throws.