Paul wrote:

Here is a picture of the alignment on my double tripod motor mount and the
combination PSRU plate and motor mount. The SS taped to the bench is the
old firewall the former owner made for the Lycoming mount. The plum bob
locates the exact thrust center line mark on the old firewall. When I get
that drilled I will use it as a pattern on the new.

Russell Kent wrote:

Actually, I don't think that the plumb bob (you actually mean plumb line, but
whatever) is the same as the thrust center line.  The thrust center line is
perpendicular to the prop and pass through the center of the hub (hopefully
:-).  Theoretically the PSRU plate is perpendicular to the thrust center
line.  So if, and only if, you have carefully levelled the PSRU plate, and
attached the plumb line to the spot on the PSRU plate that is directly
"behind" the center of the prop hub, will the plumb line and the thrust
center line be co-linear.

It looks like you've taped the plumb line in a specific spot (good), and
hopefully that specific spot is directly "behind" the prop hub, but did you
level the PSRU plate both X and Y ?

Russell Kent

Yep. That's why the exhaust manifold is on top of the plate :-)

Paul Lamar
 
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