When mounting the engine inverted on the Goldberg Decathlon do I use the pre-marked firewall center lines? They appear not to be on center, is this to accomodate a side mounted configuration or offset for a reason? Can any one give me some advice with this? Thanks in advance...

Yes, you use the pre-marked firewall center lines. No matter what mounting configuration you use, the engine crankshaft should always be lined up with the crankshaft center lines. These lines are offset to accomodate right thrust and down thrust so that the crankshaft would exit the cowl at the center.

Appreciate the reply..I assumed that might be the case but figured I would ask to be sure...Thanks again. Seeing your nickname... I'm building a Meister 100" Corsair, now that should be a challenge to fly...My first warbird.

That Corsair should be a joy to fly. I love flying Corsairs, but I haven't flown anything that big.

I have a Saito 1.20 in mine. Inverted and cut the bottom out a little. The power is awesome and it's a great combo. had problems with the cover, but it went together in about 8 hours.

Here is a pic with the Saito inverted and cowling over it. Clean!

Here is another pic