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Buly, Ed, Mark
I have an air flow diverter already built and will try it soon.  It is 1/8 foam core board covered with one thin layer of glass. 

 

       Good, hopefully that will cure the problem.

The oil filter mount came from Summit if I remember correctly.  I used the the arrows cast into the mount for oil in and out.  I will check by taking the filter off and pump oil out by turning the prop.  Oil should come into the filter near the outside - go through the filter media and exit the center - correct?

Ok, if it had markings on it for IN and OUT you are OK, some do not and folks have gotten the  ins and outs confused (your's truly for one) .  Yes, you are correct about the flow of the oil in the filter.

I have looked at the oil tank temperatures with an IR  theometer.  I'll record the data as the engine oil warms up next time I run it.

Buly - its great to hear you have such low temperatures with the same oil cooler.  There is hope for me!!  My oil cooler is from a 13 B powered Mazda
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The AN-4 line out the top of the oil cooler has an 0.020 in. orfice.  It is used to bleed out any air trapped in the high end of the oil cooler.  The delta pressure across the orfice is very low because of oil filter is the only restriction in theparallel main oil return line.  The water radiator is also using an orfice and an AN-4 line to blead air out of it's high end.   I think these blead lines should only pass a very small amount of fluid while automatically removing any trapped air.

I agree that small a hole should not be of any significance in the equation. 

Dennis,
I used the same oil cooler on my Cosmo 13B and it was cooling too  much in flight 137F at cruise.
I see one thing you have done that disturbs me. The oil line tapped  at the high end of the oil cooler going into the oil filter adapter  plate.. By doing this, great percentage of the oil is bypassing the  oil cooler core and going back into the block.
If it was me I'll block this outlet, and turn the oil cooler around,  so the oil gets in and out at the higher end. This will prevent an  air lock at the high end.
Buly