For a variety of reasons, I'm going to keep using the water temp port in the radiator for my water temp gauge (this is a 1275 in my Bugeye) for the time being. I'll need to plug the hole in the head.

What do I use for a plug? What's the thread?

Drew:

I had the same thing before swapping the head.

I got a bolt for the hardware store and threaded it in, believe it was SAE fine thread.

If you want to be even cleaner, bolt it in, cut it off with about 1/8" sticking out and then make a flat head notch in, so at least it will look like you've got a chance of removing it in the future

Pat

I just got one from NAPA a few weeks ago.
I don't remember the thread but I took my temp sender in and they matched it up very quickly, I got a plug with a hex, just like the original plugs.
BillM

ep, take your old sensor to a parts place & they'll matchthe threads & give you a plug.....I've got a handfull of them to get plugs for my Corvette engine since I'm removing all the emissions......better than a parts house is the oldest hardware store around - that has the best selection of nuts, bolts, etc.

The threads are 5/8-18 and the seal is typically made with the conical seat in the bottom.

However, what's wrong with simply using an old electric sending unit (disconnected) in the head as your plug?

I don't know that I have the sending unit anywhere. I'll have to hunt through my parts boxes and see if it's still around.

Thanks for the tips.

I just found out that the plug in the intake manifold is the exact same one as for the temp gauge-
I never knew that before, I have lots of those.
BillM

Do you happen to know what that would be, Bill, so I know what to ask for? I've not yet found my old sensor to be able to take in somewhere.

I have a spare or two, PM me your address and I'll send you one.
BillM

Thanks, Bill. PM sent.