RE: 4*120 Build Thread
Alright. Got the new firewall in. Time to set the engine in there and check the centerline of the prop hub/crankshaft.
Keep in mind that your looking at the FRONT of the plane in these pics--so left and right are backwards.
I've got 1/16" offset in the firewall. The engine needs to be mounted slightly to the left to compensate for the offset. But, the centerline of the crankshaft needs to end up exactly centered between the sides of the fuse.
This is trail and error. I'm just using a clamp to hold the engine in place while I take measurements at the crankshaft to get it exactly centered between the fuse sides.
When it's all done--the LEFT side of the engine is 3/8" away from the side of the fuse. The RIGHT side is a little over 5/8" away from the side.
So, the engine is offset to the left, and the firewall is angled to the right. Prop lines up perfect in the centerline of the fuse. Got my fingers crossed that I didn't just totally screw up and build in too much right thrust.[sm=bananahead.gif]
You can really see the offset and how much the engine is fudged over to the left in the first pic. Look closely at the side of the engine mount. Notice how much closer to the side of the fuse that the left side is. Notice how the right side is pretty far away from the side when compared to the opposite side.
The pics with the tape measure are a bit fuzzy. Sorry for the poor quality.