Vortec 454 Heater Core Bypass

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454cid

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Yeah, my plumber roommate pointed that out too. Both handles pointed vertically during the summer, point em both back toward the firewall in the winter.

Both towards firewall in the winter, but in the summer, you want both pointed towards the fender. The valve in the hose going to the heater core has no purpose if you don't close it. Having the valve between the two hoses sort of short circuits the flow to the heater core, which may be all you need/want, as it would limit the flow to the heater core (not eliminate it), which would in turn limit the heat into the cab.
 

454cid

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This is not a Vortec.

The TBI engines have a bypass internal to the water pump, I believe. The Vortecs did it externally.

Edit: assuming a small block. The big blocks all use an external bypass, back to the first Mk4 engines in the 60's.
 
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Frank Enstein

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I would use a heater control valve from an Astro with a vacuum switch. It is a bypass valve.
The one on the Wife's Astro started leaking @ 180,000 and I just replaced it again (totally my fault. I broke the vacuum fitting) @ 300,000 miles. That's reliable enough for me.

IIRC it defaults to heat.
 
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