Technical Need help with a mechanical temp gauge

This last week end I found a good sw mechanical temp gauge for my single seater project. The problems occurs with the probe, the fitting that holds the probe is 5/8" pipe and my Dodge flathead six only has two places Where the probe can go and both are 3/8" pipe. How do I adapt it down? Went to two speed shops and they didnt have any answers for me.

 

I think you need to go to a good hardware store or a plumbing supply store, I don’t think that should be that hard to fined. But I could be ugly

 

search summitracing.com for water temp sender adapter kit - with many new gauges there are adapters included.

 

5/8 pipe?
Are you sure on this?

 

If you can't find an adapter I know i can make one

 

Drill the 3/8 out to 5/8?

Ben

 

https://www.autometer.com/accessories/adapters-fitting-hose.html#2&profile=products

 

No I'm not sure if it's 5/8" was assuming it was

 

I could but my water pump housing is rare as hens teeth and I don't want to drill it out.

 

1/2 inch pipe is right above 3/8 pipe.
This pic is a 1/2 inch pipe bushing,,,the top threads accept a 3/8 pipe thread tube.

 

The left rear corner side of the head is where my sender goes in on my 230, same place on my 46 218. Is your head tapped for the heater feed on the upper right rear corner? Many heads say heater cast right into the head. The one on the water pump is for the heater return line. I can put up pics if needed.

 

No,,,do not butcher your pump housing.
There are other ways to get a temperature sensor in there!

Tommy

 

Here is a photo, I have a mickey mouse gauge laying on the floor for testing ... 5/8" to me looks about right.

 

Yes I have a sender in the rear corner but with as small as my engine compartment is my oil canister is in the way. My best option is in the water pump housing.

 

The thingy behind #6spark plug is the heater valve. You might plumb your sensor there if it's deep enough.

 

Ha ha! The whole build is ugly so it would fit right in.

 

I think the brass adapter you have with your sender is only one of a few sizes available.

 

I pulled the radiator and put a bung in that accepted the probe.

 

Here is an adapter to go from 3/8npt to 5/8 -18 straight thread.

 

There are many different size sender adapters made. I have a big assortment set (in the SW display box) I bought off Ebay a decade ago. But your local parts store should be able to get you one also. Do you have a NAPA nearby? No cludgy hardware store fitting-on-fitting parts needed.

 

Just take the gauge to Ace Hardware and go though the brass fittings there to make up the combo you need. Also you need a specific fitting for the Temp gauge bulb to tighten up in. The bulb itself seals against the adapter and the nut on the other side presses against the bulb to seal it. you need that, then you need the corresponding pipe thread adapter to get the sizes to match up in your block. Most of the bulb adapters are 1/2" NPT, a 5/8" pipe thread is huge, the nut on the capillary tubing should take a 5/8 inch wrench to tighten it up.

 

But if he stacks up adapters, the bulb won't reach into the water to read correctly. He should either order the adapter that 31aford shows, or go to NAPA and have them order one.

 

Stewart Warner for 3/8 pipe- https://www.stewartwarner.com/product/temperature-thread-adapter-nut-pn-72446-f/

 

Be careful about using an adapter that moves the temp sensor bulb out of the water jacket. I’ve made that mistake before.

 

24riverview has provided a link tothe Stewart Warner adaptor hat I had to use almost 60 years ago in order to use a SW gauge in a flathead Ford with pre '49 heads.

 

I have seen core plugs/frost plugs drilled and tapped before for a temp sensor if they are in the correct place to get a good reading.

 

Take that nut out of the adapter fitting and look at the seat that is inside the adapter for the tube nut to seal on. That is why you can't use a regular bushing from the hardware store. SW, Autometer, and most all the gauge companies make adapter fitting that go to 3/8" ,1/2" sizes. That is what you need to source at whatever performance shop you use. Regular parts stores don't even usually stock them.

 

That adapter won't work because the 5/8 thread is straight. It needs to be a tapered pipe thread.

 

I disagree with your conclusion. The part @31aford linked is the same as @24riverview recommended and I believe they are the same and also correct. Those fittings have the bulb seat in the fitting bore along with straight threads for the bulb retaining nut.

Ray

 

Yep, the internal threads are straight and the bulb has a taper that creates the seal. The male end has the pipe threads.