oil temp sensor placement
 

Where is the best place to put an oil temp sensor? I'm running a Hardin XS 10 qt pan and a merc hp 500 horizontal mount themostatic oil filter housing. I can mount it in the pan as there are plenty of fittings in it for that or there is what appears to be a spot on the filter housing. I think this is where the choke switch goes but I will be running a pro-systems carb and won't have a choke. Thanks in advance!

in the oil filter housing. That is where Hardin told me to put mine.

I have always heard in the pan. In fact, my engine builder welded a bung in the pan so he could put it there.

I've read in the pan a lot also, but the shear heat the oil sees after going through the oil pump should also be taken into account. I measure mine before the cooler. Best case scenario is before and after the cooler.

I have heard that some people put a 270*F alarm sendor in the pan which I think I just might do. Ill tie it into the alarm buzzer and a LED.

I'm having Dave @ Wesco build my short block. I'll see what he says when I pick it up.

My vote is for the the oil pan.

I put them either in the oil filter housing (after the cooler) or in the block only if they are in the flow of oil. You do not want to put them in a dead end passage that is not directly in the flow of oil. It will not read correctly.
By putting it in the pan, you take the cooler out of the equation. Lets say the oil is 250* in the pan. If you have a larger cooler than the oil going into the engine may be 200*. If you have a smaller cooler, than it may be 230*. I want to know what the oil temp is that the engine is seeing, not what it is after it has made it way through the bearings and been beat up by the crank.
In a Gen VI block, a good place to put it is just above the stock oil filter pad. In the aftermarket blocks, I put it in the filter housing.
Eddie

Eddie,
What do you suggest on a Mark IV block? In the block or remote adaptor?

Eddie thats what I was thinking ,what the temp is going back in is.

I guess another way to look at it say if the oil in the pan was like over 350 ,that would so a problem?

I would put it in the oil filter housing. On a Mk IV, the oil passage just above the stock oil filter pad is quite a bit from the main flow of oil. If you look into that passage, you will see that it is at least 3" to the main oil galley. I would think that is far enough away from the main oil flow so that you may not get an accurate reading.
The most ideal situation would be to have 2 temp sensors...one in the pan and one in the block or filter housing. That way you would know how hot the oil got and how efficient your cooler is. It's just not that practical for most boats. Most don't have the room for another gauge.
Eddie