I have an article from RCM from Sept. 2000 on how to make a cowl from balsa. Appears straight forward enough after reading it a couple times. However it mentions that the engine mount that comes with the kit will not work for a balsa cowl. It does not state why and by looking at the engine, engine mount and firewall can not tell why it will not work.

I have the tower hobbies .75 ABC engine with a .76 Bisson pitts muffler and was planning on installing the engine sideways.

Anyone know of the reason why the supplied engine mounts won't work?

If no one can explain why, go ahead with your plan, but be prepared to make a trip to the LHS for a new mount if you encounter a problem.