I give up!! Need to order the Bypass hose that runs from back of Thermostat/water pump housing to the rear Housing on our 1986 13b I can't seem to find in my parts book. Need pictures Thnaks Tom W
You don't need the flow. The stock setup doesn't flow much at all through that line. The line runs from the rear iron to the throttle body thermowax cam and from there to the water pump. The thermowax has a pin hole size bypass which, I would guess, is only there to allow any air bubbles to escape.
On engines where we don't use the thermowax, I typically cut the hose barbs off and drill and tap the water pump and iron for a 1/4 NPT plug.