>When I look inside the portion
>of the steel tube that this hose fastens to, I find that the hole
>drilled into the main tube is only 1/8" diameter, whereas the rest of
>the passage for the coolant through the manifold is 1/2" diameter. Now,
>this little bitty hole may be sized for manufacturing convenience, or it
>may be a conscious effort to reduce flow.
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The hole is indeed smaller in dia to provide a restriction for flow
control. In this way, when you have the heater valve closed you have a
metered amount of coolant flow through this small hole (to provide for
manifold heating), but when you open the heater valve the restriction of
the valve becomes less then the small hole in the tube and the coolant,
taking the path of least resistance, will flow through the heater core
instead. If you enlarge this hole you won't get the proper flow through
the heater, and little or no heat-
Barry Schwartz (San Diego) bschwart@pacbell.net
72 V6 Spitfire (daily driver)
70 GT6+ (when I don't drive the Spit)
70 Spitfire (long term project)
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