The Stovebolt Site Forums The Shop Area Interiors Water Temp Gauge Fitting at the Head

I have a new set of gauges and noticed the water temp sensor (mechanical) has what LOOKS like a 3/8" NPT fitting on it that spins so you can tighten it down. It is not 3/8" NPT, not 1/4" NPT. What is supposed to be in the head that this fitting fits into?

Miss info. Delete
dg

Where do we get such a thing? Is it just an adapter bushing or something very special for this purpose?

This seems a little high!
http://www.marks4wd.com/mfc707.html

What year head?

58-62 848

Thats perfect! Thanks! I have never heard of UNF fittings before. It is a pretty hard to find item. Good thing they last a long time!

For recording purposes:

VDO Part Number 701-1798
5/8-18 UNF to 1/2-14 NPT

also, VDO Part # 180-066 is more available and seems to do the same thing.

From this description from the link above, it appears the manufacturer used TOYOTA sender with those threads.

from the link:
Kit Contains: •Adaptor fitting

Water temperature adaptor GM and Ford engines to Toyota sender most models — Adaptor fitting (straight type) (male end 1/2"bsp-t 14tpi female end 3/8"nps 18tpi

Alvin, I am looking forward to your new movie, but I just wish GM would have stuck with NPT and not done something so off the wall and unprecedented just to fit a sensor into the head. 3/8" NPT is sensible, but going to UNF reminds me of when they went to metric for disc brake calipers for a few years. Idiot hired, Idiot fired, moving on... LOL! Toyota and GM in the same sentence? AAAALLLVIIIN!!

The adapter which you are obsessing over in a compulsive manner is an aftermarket adapter (not GM) so that we can use the temperature gauge which belongs on a 216 head on a later model 235 (which has too big of a hole in it for the bulb).
Carl

Readily available and costs about $7 from most vendors.

Doesn't change the fact that if you have a 216 and you decide to do a test run on an engine stand, and you go to plug the water temp hole, (or you want to put an electric sensor in the hole) you have a problem because everything else on the engine is NPT and that one is UNF. Maybe what you could do is just stuff a cork in there? LOL! Or.. just wrap a 3/8" NPT plug about 50 times with teflon tape. Aftermarket came to GM's rescue on this one. Nothing a lathe and some special taps wouldn't resolve I suppose as the supply runs out.

Or screw in the stock gauge in the hole of the 216.
While I do enjoy your frequent outside-the-box thinking, many times the easiest solutions are actually inside the box.
Carl

Standard 5/8-18 UNF cap screw in a 216 water temp port here:
http://www.pbase.com/dennygraham/image/162201936
No reason this couldn’t be cut short and a fiber washer used under the head to seal it if
that’s the objective.
Or the end could be turned on the lathe to match the seat and a dead soft copper washer
place in the seat to seal it at the end
Don’t quite know what the problem is with the ½”-14 NPTF in the 235 head. Any standard
½”-14 NPTM fitting could be used to plug it or adapt it. Here a ½” nipple could be capped:
http://www.pbase.com/dennygraham/image/162201937
or in the next one:
http://www.pbase.com/dennygraham/image/162201938
a pet-cock could be installed or a standard ½”to ¼” reducer bushing
could be tapped for a 5/8-18 UNF thread to seal it up or a standard ½ to 3/8-18 NPT
reducer bushing will even take a 5/8-18 UNF cap screw with a fiber washer. And of course
if you need to use the mechanical bulb in your 235 there is always the adaptor that has
been linked to a dozen time here. It the problem is using an electric sender in you 216
head, then a 5/8-18 cap screw drilled and sealed with a copper washer in the seat and with
a ½ NPTF bushing brazed to the head would work just fine.
With all those tools in that shop of yours Deve, I'm sure
you have a lathe somewhere in the shop, make an adapter from
a piece of round stock to take a 1/2 NP and thread the end
with a die to 5/8-18 UNF.

dg

Yep. You get the actual idea. It's about helping the next guy that comes along needing guidance on what to do about this. A friend tried to get the adapter from the vendors and they were out, so local auto parts is hit and miss on these nuanced items, so I have a few coming from another friend. Now that this thread is available, they won't think it is just them.

One inquiry, the guy said, there are only two possible threads for these American made vintage vehicles, 1/2" NPT and 3/8" NPT so how hard can it be? Now the next guy will have everything he needs right here. Thanks Denny, Alvin, Dads50. Everyone else who posted tripe, you should be embarrassed, but you aren't. That's the pathetic part.

Pharber is that YOU?
It really sounds like that six hours of passive aggressive classes you took has helped out a lot.
The Anger issues are being kept well in hand (and your holding on till the end of posts to release them!)and the A's you got in the previously mentioned class are definitely showing.
Yellow Star.

tripe?

It is a fact the diameter and thread type changed.
It is a regularly posted fact that the diameter and thread type changed.
Many vendors sell an inexpensive adapter.
This is cheap to adapt/adjust for.

Those who did not know about this, now know.

Let's call each other colorful names?

Let's go to the Greasy Spoon to speculate why, and, to speculate why anyone cares why?

Glad I could help.
You are welcome.
Carl