The Stovebolt Site Forums The Shop Area The HiPo Shop Sending Unit I.D.

My manifold upgrade project is coming along well.
All vacuum plumbing issues are resolved, thanks in large part to the help I received here in HiPo.

This should be easy - someone tell me the purpose or function of the sending unit in the picture. I believe that oil pressure is the canister next to the distributor, and coolant temp is near the thermostat, so what is this one?
Elementary, I know, but I drew a blank today.

Thanks in advance; enjoy the picture of the engine bay in progress.

If that's in the cylinder head it's for the temp gauge. Looks like a one wire sensor.

The single terminal brass unit is a thermistor type sending unit, it will operate a gauge, the 2-terminal "switch" in the manifold is a liquid temperature switch for an idiot light or electric cooling fan or emissions control. I can't make out an oil pressure sending unit.

Ah , that’s my mistake. I thought the 2 terminal unit was coolant temp - that’s the fan control sensor. I should have figured that out. Bad day.

The oil pressure sending unit is still on the bench.

Like I said, bad day , I was quite distracted.
I guess that’s why I installed the nice new thermostat house while overlooking a certain detail.
The thermostat is still on the bench too , right next to the oil pressure sending unit.

Side note : my truck is stored in the winter , no real cold weather starts. How badly do I need a thermostat?

The thermostat helps the engine reach operating temperature faster by restricting water flow to the radiator. Once the engine is at or near normal operating temperature, the T stat opens up to allow most or all of the coolant to reach the radiator.

Whether the outside temps are hot or cold, you want the engine to reach operating temperature as soon as possible.

I understand the function of the thermostat, just wondered about it given the situation.
I’ll correct my mistake tomorrow.

Yes, absolutely use a thermostat. The normal T-stat range for a small block Chevy is 160 - 190 degrees, I like 180 degrees. Your thermostat housing looks like a heavy duty piece, keep an eye on it when you get everything running, I have not had good luck with the O-ring style housing in years prior, went back to original GM housing with gasket.

I went with the O-ring because I could not find a fixed piece with the right configuration. The radiator fan control is a dictating factor.
I did apply a thin film of Permatex to the block surface and to the O-ring, hopefully that will increase the likelihood of integrity.

Of course, I get to undo all that to correct my dumb mistake of leaving out the thermostat. (I planned to do that today , but the surf was too good to pass up.)

If you're out on the pond you could let the wind just push you all the way across to the Wolverine state, we could set up a visit with others.

Wind is offshore again today, northwest at. 15-20 mph.
I’d expect to make landfall around Indiana Dunes.
Surfing again today, fixing thermostat error pushed back to tomorrow.

Has anyone ever used a conventional gasket, possibly with Permatex, with the installation of one of those adjustable t-stat housings?

You might get some "white out" conditions on the way down lake, let us know how it works out! I have not tried a gasket with that style housing, if it has a good flat surface that will match up to the manifold then I don't see why a gasket wouldn't work.

When I get to the shop tomorrow I will remove and clean the housing & O-ring then eyeball the assembly to assess the feasibility of incorporating a gasket.
My confidence in the o-ring alone is not real high.
I’ll report on the results.

Didn’t enter the water today; the conditions were a bit wild for my liking. At 72 years of age I figure it’s ok for me to pick my days. Getting “worked” in 35 degree water is all that funny anymore.