# 1965 Exhaust manifold questions



## kanthonyk (Jan 18, 2016)

Hello,
I may be in the minority here, but i will be removing the headers on my 65 GTO, and installing factory exhaust manifolds. I bought a nice set of OEM manifolds and i noticed the one side has a spring and a lever. I assume it opens with heat in some way. Just curious to the purpose of this. Also, did anyone ever clean and paint them? not sure what is correct paint or coating would be.

Thanks!


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## El Monte Slim (Sep 8, 2014)

It's known as a heat riser valve. In cool or cold weather, the "spring" is a thermostatic coil that closes the valve in cold weather and opens the valve when the engine warms up.

When the valve is closed, it forces the exhaust from that side of the engine back through the intake manifold to warm the incoming air and fuel mixture, improving the cold weather driveability.

As the engine warms up, the thermostatic coil opens the valve and allows the exhaust to pass normally through the muffler and tail pipes.

I don't know about 65 GTOs, but on 66 GTOs, the driver side muffler is a bit larger than the passenger side muffler because it handles the exhaust from both sides until the heat riser valve opens.

When my car was restored, I had the exhaust manifolds ceramic coated.


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