I read the directions for my Phoenix Extra and it says to mount the engine 4-3/4" from firewall to front of the drive washer. The problem is it wasn't enough to fit the cowl so I need to move the engine 3/4" forward. I was thinking of beefing up the firewall but I didn't know what wood to use.
Any help would be appreciated.

thanks, Chris

Make up a lamination of 3 layers of 1/4" aircraft plywood to fit between the engine mount and the firewall.

Oh good I already have that
Thanks alot.

chris

Like so . . . except this spacer is 1".

Another alternative is a prop shaft extension. Fox makes them in 1/2" and 3/4" and for 1/4-28 thread and 5/16-24 thread crankshafts, so if your engine's shaft has one of those threads you could just leave the engine where it is and move the propeller forward.

Moving the engine forward will move your center of gravity forward too. THis may be a good or a bad thing, depending on how your airplane is balanced. If it was tail heavy to begin with, moving the engine forward will help. If it was right, or if it was nose heavy and you had to add weight to the tail, moving the engine forward will make things worse.