77 Elcamino Exhaust manifold lever?

1977 CHEVROLET EL CAMINO
170,000 MILES
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ELCAMI
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hi,

I found some lever (switch?) under the Exhaust manifold with broken metal wire.
I believe that this block the output gases for cold days. could you tell me where it belong? or which side I should turn it to be open? (I live in hot country)

thanks
I really appreciate your professionalism
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May 31, 2011 at 8:28 AM
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WRENCHTECH
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That's an old "heat riser" valve. It's designed to redirect hot exhaust back through a passage in the intake manifold to heat the fuel during warm-up. There used to be a vacuum control connected to it to operate it.
May 31, 2011 at 11:40 AM
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ELCAMI
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thx for your replay.

how can I know which side is open, following he red or blue arrow ?
(blue is closer to engine block)
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May 31, 2011 at 12:24 PM
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WRENCHTECH
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Since the vacuum control pulls up, I would expect up would be the closed position but I don't really remember. You have have to figure that out.
May 31, 2011 at 12:30 PM