[brian12c]

on a gen 1 sbc head what is the hole for that is on the exhaust side in between the far left and middle exhaust port? thanks BF

[F-BIRD'88]

temperature sender unit

[xntrik]

Originally Posted by brian12c

on a gen 1 sbc head what is the hole for that is on the exhaust side in between the far left and middle exhaust port? thanks BF

Temperature sender in the driver's side head.

The built-in water pump bypass is on the passenger side, so the driver's side head tends to run hotter.

Also the stock SBC water pump tends to flow more on one side than the other in varying conditions.

This picture shows the bypass plugged with an allen head plug for racing purposes only. Don't do this on any street car without other provisions for bypass.

[brian12c]

so is this only for vehicles with a computer or is this what sends the signal to the water temp gauge?

[NorthStar]

Computer controlled engine has another temp sensor in intake manifold located near thermostat. The sender unit in cyl head is for gauge or light on dash.

I think theyve used that location pretty much forever and always drivers side. So its one thing to pay attention to when bolting heads back on, can be really difficult to get the factory plug out sometimes.