This is an old schematic but it is simple and clear. This is what I would
do in
your case Mike. Add a hose from the heater outlet back to the input to
the rad. Since the restriction in the return side of the water pump was
probably put there to enhance the water flow through the heater, re-routing
the heater flow back to the input to the  rad should enhance the flow through
the engine slightly without modifying the pump or adding another cooling
core.
Since you have plenty of space above the engine in your RV4 so you do not
need a
modified, low height, low restriction water pump. The higher temp of the
water out of the back of the block should slightly improve the eff. of the rad
and slightly reduce the overall temp of the engine. The down side is
of course slightly more banana.

Thats about what I was thinking too Paul. Tracy, I would like to hear from
you about what if anything you do with the heater loop.

Mike, why don't you fly up with Dave to Santa Paula on the Fourth.
I am sure he would not mind sharing the cost of gas :-)

Yeah, we are trying to work out the details. I dont know if our schedules
will line up. Im waiting to hear back from Dave. Being there for the
airshow would be an added bonus. We are partners (along with a bunch of
other guys) on the Cessna 140 so our scheduling has to work around the
other partners as well.

Thanks,

Mike Wills

I measured the heater outlet pipe today and it  is about .53 inches in diameter.
The area would then be 0.22 square inches. About one third the restriction
area (.66 square inches) in the outlet of the pump. So using this heater outlet 
should help the flow greatly with an unmodified pump. The total area (.88) is still 
not up to the area of a 1.25 inch ID hose or 1.23 square inches.
Modifying the pump is still a good idea IMHO.

Paul Lamar
 
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