Temp sending unit size?

Got the sending unit and gauge installed. I think it's working??? It seems to stay around 120. This is sitting in my yard running at idle or just above idle for a good while. In fact, it was probably idling for 10 minutes last night while I was messing with the carb. At one point it seemed to heat up quite a bit, the thermostat opened, then it cooled back down to 120.

Does 120 seem low? Or is it just low because there is no real load on it?

Is there any chance that since it is shorter than the last that it's not touching the water? Shouldn't the entire cavity be filled with water?

David,
As long as the ohm range. I'm 99% sure it's a 33 to 240. You would need to have some real odd gauge for it not to be that ohm range. The new sender being shorter is fine. It will be in the cooling water and sense the temp. In fact, due to it having a smaller sensing tip it will react quicker (less mass to have to heat up).

BTW, do not use any thread tape or compound on it. The body needs to be grounded to the block via the threads. It being brass, the threads will seal by themselves.

David,
To short or pipe threads to small? Shorter may be ok. The end of the sender will still be in the water jacket.

it is 3/8"'s

David,
Just below the hex on the body where the pipe threads start.

David,
You'd better measure to be sure. 3/8 pipe will be just over 5/8" dia. (.675") and 1/2 just under 7/8" (.840")