hey guys i have the avistar AWARF and the avistar RTF , well needless to say the RTF was damaged and am fixing it, the problem is i bought another one the avistar AWARF and it coes with an adjustable engine mount... how the heck do i mount my 40LA on this? i was going to use the metal one from the RTF kit but the BOLT PATTERN ON THE FIREWALL DOES NOT MATCH!!!!
what am i to do? this plastic mount seems like a pain in the arse...
also why is the pattern on the firewall different?

The bolt pattern is different because the mounts are different.
Welcome to the other side of the hobby. While learning to fly is important, also important is learning to repair. One of the facets of repair is sometimes modification. You can mount the 'LA on the plastic mount by drilling the holes for the engne you wish to use in the right pattern on the mount rails. With the AWARF, you also must fit the throttle rod. These items are not prefitted or drilled so that you can fit the engine of your choice to the model. Fit the engine to the rails with 6-32 screws and nuts. Use a bit of loctite. You can also use the old mount if you wish. You will just have to fit it to the new firewall and drill holes as needed. Install new T-nuts and maybe plug the unused holes with a bit of scrap wood glued into the holes. Seal these wood plugs with a bit of epoxy for fuelproofing. Talk to the guys at the field. They'll teach you.

Not sure about your's, but the adjustable mounts I've seen have plastic tabs at the rear of each half that must be cut out. Then it should be clear how the two halves slip together, and can be adjusted in width.

Good Luck midnite. It does get easier.
Dennis-