Recently swapped a late sixties /6 into my '62 valiant. The temp sending unit in the late block was different than the early unit, so i put in a brand new one. The temp guage showed the car running hot. I had the radiator rodded, pulled the thermostat, checked the timing... guage still showed the car as hot.

Took it in to the radiator shop-- they ran some tests and said the guage was off, the temp was fine. the guage worked perfectly before the engine swap.

Are early/late temp senders and guages calibrated differently so as not to be interchangeable? Anything I can do other than go to an aftermarket guage?

tim

I had some gage problems a little while ago. My temp gages was fried I guess. I pulled a gage from a 75 Valiant and my sending unit read low. I swapped in the sending unit from the donor car and it now works fine. I'd put the sending unit from your old engine back in if you still have it or can find it.

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I put a rebuilt engine in my 63 Valiant a few years ago and ran into some of the same problems. The head on the rebuild was a later model and had a smaller diameter sending unit screwed in the head. It appears the sending units from 60-63 were larger than the later models so the old sending unit won't fit in the later block without drilling and tapping the hole the smaller unit occupies. An alternative is to install an after market sending unit and gauge together as a matched set. If you can measure the resistance of the old unit at various temperatures and then measure several of the newer style units until you get a close match, you might be able to use the gauge in the dash. Might be worth it if you have the time to fiddle with it and the car will remain more stock if that's important. Good luck. RMDV

Carl Zeamer

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Carl Zeamer. an old guy, please be gentle.

this thread sounds very similar to the other sending unit thread going now... Someone mentioned an adaptor for the temp sending unit?

The early style sending unit is 1/4, '64 and up are 1/8. Is there an adaptor available that would let me use the old sending unit in the stock location on the newer block? And, apparently the drain plug is 3/8... is there enough clearance in the water jacket back there to use the sending unit there if I can get an adaptor to convert the 3/8 to 1/4?

There are brass/aluminum fittings to adapt all sorts of sizes, check your local hardware store in the plumbing section. If there isn't enough room depth wise to put it in the side of the block you can always get brass couplers to space it out. With various male/female fittings you can go from small to big or big to small thread without a problem so as long as it is a tapped NPT hole your fine. There are also 90deg elbows availible so if it gets in the way of something you can use one of those to mount it in a different direction.