Here's one for the pros..

On top of the water pump housing, there is an internal hex drive pipe plug, which blanks an unused hole on top of the casting.

I'd like to know if anyone knows the thread type of this plug, before I pull it out. I'm putting in an Autometer water temp gauge, and I will either use a supplied imperial adapter on the 1/8" NPT sender probe, or if the tapped hole in the casting is not imperial (I'm 100% certain it isn't) I'll get in the lathe and make an adapter with 1/8" internal thread, and XXX-whatever (metric?) external thread to go into the casting.

My bet is its metric. Although I have seen some odd threads near the oil filter that were not metric according to my thread gauges, and turned out to be some Japanese proprietary thread that I had not seen before, (but I was still able to set my lathe up to cut)

I dont have my thread gauges here with me. They're back at another property, where the lathe is.. :/

Thanks guys.

 

*What I meant to say was the pipe plug on top of the filler neck housing :s

It takes an 8mm allen wrench to remove it, and just for the hell of it, I tried to screw the 3/4" NPT Autometer adapter plug into the casting, and it actually screwed in...

I was a bit shocked that it was an NPT thread, but oh well. Problem solved. Gauge now works fine (Autometer Metric series 3335-M, 2/16")
problem solved.

 

I imagine its m10 or m12. I'll find out for you tonight if you like, as mines off the car atm.

Personally I just tapped mine into the front, though. I'd think this would be a better location & you can tap it to 1/8" NPT.

 

NPT is a tapered thread, my holes are defiantly not tapered. But you're saying that yours are?

 

Search for my thread on how to install a coolant temp sensor. Installing it in the thermostat housing will give you NO reading until the car is warmed up and the thermostat opens. If you have a stuck or failing thermostat, you may not know until too late.

Dale

 

If that was aimed at me, I monitor temperature on the PFC commander utilizing the stock sensor until the t-stat is open. I actually quite like having the two separate as when my gauge suddenly springs into life, I know my t-stat is working

 

Dale: Installing it in the thermostat housing is a good safety measure for me- If the gauge doesnt read until the thermostat opens, then I wont start boosting it and giving it a hard run until I see the thermostat is open/gauge begins to register normal temps.

If the gauge fails to register a temp, I know the thermostat is stuck

Ceylon: Yes, up top next to the filler cap, I took the hex plug out and I have a tapered thread in there, appears to be NPT, as the NPT fitting screwed in by hand...
I know I was expecting metric too, and it surprised me. All I did was wrap some white teflon tape on the fitting thread and screw it in, done. I'm assuming nobody has ever re-tapped the casting to NPT, as it looks all original to me.

 

Can anyone confirm this is correct? I need to get a new plug for this top hole.

Ceylon's comment above is the reason I'm asking for someone to confirm, thanks in advance

 

What happened to your plug?

That sounds about right but I'm not 100% sure. If you are in Orlando there should be larger hardware stores that should have something you can test it out and make sure you have the right size.

Dale

 

My car has the Pettit racing low temp fan switch installed there, I’ve got everything ordered to fix this and change to the FC switch in stock location, just need the plug.

I called Pettit and he told me both the side and the top holes are 3/8” NPT, if that’s true at least the threads won’t be damaged since the switch is meant to be installed on the side of the housing

 

I'd expect zero chance of them actually being NPT . Everything else calling for a Japanese tapered fitting is the equivalent of BSPT. Slight thread count difference, being a tapered fitting and addition of teflon tape enables a kludge to work.

 

I picked up a brass plug locally that matches what Pettit told me. Those that have installed the low temp fan switch in the correct location haven’t complained about the threads so I’m guessing it’ll work. I’ll have time this weekend to get everything installed and report back if that thread works

 

Just for reference, whitworth thread 19tpi, not NPT...but no doubt will sort of screw in, due to diameter difference.