I am working on an ARF that has minimal instructions. The instructions on mounting the engine show a different engine mount than the one that was supplied. If I mount the engine the way it says then the cowl will not even come close to being centered on the engine. My question is how do I determine the thrust line so that I know where to mount the engine? Should I just line up the engine with the cowl? It is an Atec Models Excel 3D. Paid $50 for it plan to mount a Saito 65 for starters and then put in the Saito 91 if I decide it needs more power.

Thanks,

No answers, can anyone give me any hints? I found some threads that said it won't hurt to move the thrust line a little. Can I get away with it?

Being an ARF you may get A better answer in the ARF forum from someone that has assembled that plane. Some planes, kit or ARF have the thrust angle built into the plane by angling the fire wall so you can just set the engine to the cowl. Others have A straight fire wall and you have to set the engine angle thrust then offset the engine so the shaft is centered to the cowl. This can be done with A beveled wooden shim, some people just use washers behind the one side of the motor mount. Shims are better. I have bought plastic shim sets from different hobby shops in the past that are angled to different degrees that work great.
I really would go post up in the ARF Forum and see if you can find anyone that has done it to this plane.

This [link=http://www.lcrcc.net/offset_calc.htm]Online Thrust Line Calculator[/link] will probably help alot.

I find that people who build kits have a lot more knowledge of building techinques that those that "build" ARFs. I am not as much concerned about left to right because that is already set in the firewall. My question is more about the vertical centerline of the engine. Do I want to be in the center line of the horizontal stabalizer? This is a low wing 3D style plane with a thick wing cord and large control surfaces, much like the U-Can-Do type planes.

I would do as you stated. Line up the engine with the cowl that's were the thrust line is supposed to be. Otherwise the cowl will not align. If this appears to be a problem perhaps you may have to mount engine inverted or on its side. What engine is shown originally?