Aftermarket Water Temp Gauge fittings.
 

Hello all, i have a question. Im looking to install an aftermarket water temperature gauge(sunpro or autometer) in my 85 gls. I want to use the stock location for my aftermarket sender under the oil filter on the rear iron. Now i know this will disable my cluster water temperature gauge, but i don't mind. My question is do i need an adapter fitting for my aftermarket sender to fit the rear iron or will it screw in? Wat size adapter fittings do i need? I have done research but it seems like everyone uses the temp sensor for the choke next to the water pump, and i don't want to tamper with this as my car's carburetor is still all original. Also i don't want to install those inline radiator hose adapters either. So any help is appreciated, Thank you.

It really depends on the size of the after market sender. Most I've used are 1/8 NPT . I'm not sure what the factory size is.

My I suggest placing the after market sender in the thermostat neck. I used an early pre-1979 thermostat neck and just tapped a 1/8 NPT.

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m8 x 0.75 is very hard to find aftermarket..

and i would think a m8 x 0.75 male to female 1/8 npt adapter is non existent except custom

the location in thermoneck top will be lazy until thermostat opens

many blocks have a threaded bung into the water jacket,, in the final pass
in the front plate, down the spark side

( behind the A/C and P?S pump bracket )

if you have one

take it out,, tap your 1/8 npt tap through it . and fit the sensor there


else.. back of waterpump

Another thing I didn't mention is that I'm running an S4 water pump housing in my 12A engine. I removed the water nipple from the back of the S4 housing and tapped it for another water temp gauge. This way I can measure the temp before and after the thermostat.

I know this is extra work, but you could remove the water pump housing a tap it for a sensor.

Here is the S4 water pump housing and the changes that where required for it to fit a 12A. The big tapped hole is for the 12A factory sensor. The smaller one is for the after market sensor. the oval opening has an extra stud hole that needs to be sealed off with a plug using a helicoil and plug.
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On the heater outlet on the driver side but you need a brass "tee/wye" if you need the heater

Thanks all for the help. Yes i see what you did. Thanks for the info. I looked in the archives on how to fit a s4 water pump housing in a 12a. Looks like the only thing needed is to plug that hole in the oval section and its a straight bolt in affair. I think im gonna go this route. Do you happen to know the tap size big hole/stock sensor? And my gauge utilizes a 1/8-27 npt probe.

The stock sensor is M16x1.5.

I used a M8x1.25 helicoil for the oval hole and a M8x125 plug. I recessed it a tiny bit and then used some ATV silicon as extra insurance it did not leak when I installed it on the engine.

One other note. I used the S4 water pump, S4 water pump pulley, and the upper and lower S4 air pump brackets . I did have to hog out the four holes for the clutch fan spacer so it would fit the spacing of the S4 pulley.