Inliners International Forums General Discussion Hi Performance ???water temp sensor port in 292 head

Hey guys! I am curious to know if it is true that you get a false water temp reading at idle because the temp sensor is so close to the exhaust ports. I have read elsewhere that some guys get a temporary spike in the water temp at idle.

I'm just trying to decide if I want to pick up my water temp at the head or somwhere else.

I also believe that is true and try not to use the head located sending unit. If mounted in the lower thermostat housing, the temp would be more "even" or not fluctuating as much. One problem is the intake line can also "cool " that same area.

Tom Langdon specifically told me the head temp sensor location causes spikes at idle. That's why GM started installing them in the thermostat housing boss.

It was one of many, many things he covered with me in an hour over the phone. Man is a wealth of knowledge.

...and I didn't end up moving mine. I, instead, opt to ignore the spikes. If it goes over 210 then I start paying attention.

Tom, would something like this be a better option. I am assuming that this top port is the return from the heater (correct)? Or should I move it down to the lower port where I have my return from the heated intake?
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Am I correct in assuming it is best to pick up the water temp. from a location as close to the top of the head as possible?

Because I also thought about picking up the water temp here at the supply for the intake but seems like the metering block would be alot of weight hanging on such a small fitting coming out of the block. I guess I could make some kind of support bracket and mount it to the bell housing bolts.
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Direction of coolant flow is not always obvious. The upper heater hose is actually the source of coolant flow from the block (note it is below the thermostat - which is normally closed). The lower heater hose is plumbed into the water pump inlet creating draw from the block through the heater core and 'returning' back into the block (even when the thermostat is closed). That is when the manually controlled passenger compartment heater "demand" valve is open thereby calling for heat.

When the demand valve is closed there is no coolant flow through this circuit. So the closer to the thermostat the more accurate the temperature reading is likely to be.

As for which is the correct location for a single temp gauge . . . why not fit two? If there is a huge temp spread between the liquid just below the thermostat and the steam at the roof of the combustion chambers (near the exhaust ports) might it not be a good time to pull out of the parade or Woodward cruise and park it?

A temp sender fitted here is likely to 'cycle' showing thermostat open/close events oscillating between a lower and a higher reading as the thermostat does its job.

I think that the stock location was designed solely for a 'pull over now' idiot light.

The beauty of instrumentation is that one can measure as much as one sees fit.

BTW. Your setup is over the top pretty. I love all of the details contrasted by different colors.

stan z.

I would like to know more about your exhaust headers and some more photos if possible. Did you build them? Thanks and sorry for the hijack... thanks.

Ask and you shall receive..............Headers were made by a company called Stainless headers Inc., they send you a PVC mock up kit with the flanges for your motor, you send the mock up kit back with a head gasket and the tubes all pinned together. In about 6 weeks (AND A WHOLE BUNCH OF MONEY), you have a one off set of custom headers. Dam things fit perfect!
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I had to have these headers made up this way so that I could run the front set under the oil pan and over to the passenger side. This is because I had to move the master cylinder off the firewall to under the cab so I had room for the carb . Unfortunately there is nowhere near enough room to run both exhaust tubes in between the trans and master cylinder under the cab
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Direction of coolant flow is not always obvious. The upper heater hose is actually the source of coolant flow from the block (note it is below the thermostat - which is normally closed). The lower heater hose is plumbed into the water pump inlet creating draw from the block through the heater core and 'returning' back into the block (even when the thermostat is closed). That is when the manually controlled passenger compartment heater "demand" valve is open thereby calling for heat.

This still has me somewhat confused......In my other thread about heating the Clifford intake, It was said that the lower port on the T-stat housing is at low pressure and allows the intake to evacuate. If that is true how can the port directly above it be under pressure to supply the heater? I have to admit I am pretty stupid (barely made it out of High School) but for some reason my common sense tells me that the intake is not evacuating but is being heated by staginate water until the T-stat opens. This makes my head hurt!!!!!!!!!
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Let's go back to your original picture from the other thread:
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If you are plumbed only into the block side of coolant circuit this is likely the case. There is no difference in the pressures/flow between those two holes on the passenger side of the thermostat housing.

The thing to keep in mind here is that every opening in the water pump housing is an inlet sucking/feeding coolant to the impeller spinning in the block. So the stock plumbing for the heater core is the nipple on the thermostat housing (flowing from the block to the core) returning to inlet on the water pump just above the lower radiator hose.

If your Clifford is plumbed to the rear pet cock drain hole and the thermostat housing then there is no direct action from the water pump on that circuit.

What I have no experience with (as I am a stovebolt guy) is the third re-circulation input on the drivers side of your set up. As I understand it - this creates constant positive flow from the top of the block back into the water pump which in turn pushes coolant back into the center of the block. In the stovebolts the water pump simply presses against the water pressure in the block waiting for the thermostat to open.

This re-circulation may promote some flow through your Clifford.