As far as the rear mounts go- I was thinking of having a cross brace
from the upper left firwall attach point to the upper right engine
mount point. I can't fit one going from the upper right firewall
attach point to the upper left engine mount point- it interfers with
the water pump belt. I can't( or shouldn't) have a cross tube going
from the upper right firewall attached to the tube that goes from
the upper left firewall to the upper left engine mount, about the
midway point in the upper left tube, correct?(Anyone follow that?)

The upper right engine mount bracket is pretty close to what Mike
Wills is using, but he has lightening  holes in his. I made mine and
then saw that it was just about identical to his.

The distance from the firewall to the water pump housing is 14"- so
firewall to prop flange should be 44".

So Paul, I think I'll take your advise and cross brace the upper
mount points. Any more input is apprciated. Brian Trubee Redmond,Wa

Brian,
Is this the distance to the water pump housing or the pump shaft flange?  My 10"
measurement is to the face of the water pump shaft flange.  If you are 14" out, your
CG should still work out.  I was amazed at how far forward the engine could be
moved and still stay in the CG range.  I have attached the results of my calcs.

Ken P.

Here are the results of my CG calcs.  These assume a 110 lb pilot, no fuel and 35 lbs of baggage.
This should be the worst case scenario for a RV-4.  The calcs are based on the CG of the engine,
not the location of the prop flange.

2" forward - 70.63
4" forward - 70.11
5" forward - 69.85
6" forward - 69.59
7" forward - 69.33
8" forward - 69.08
9" forward - 68.81

Note that the allowable range is 68.7 to 77.4, and with the Lycoming the CG
was at 71.18.  The CG of my engine is 4" forward of the Lycoming.

Ken Powell

You are a tiny guy Ken. You sure looked heavier than 110 pounds the last time
I saw you :-)>

Paul Lamar


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