TR2/3/3A Plug/cap sizes to block off heater

[jfarris]

My apologies, I just had a second heater valve fail in two years, so I'm thinking of blocking off the heater that almost never gets used. I have searched everywhere for the sizes of the cap (or plug) on the back of the water pump and the plug replacing the heater valve at the rear of the cylinder head that would isolate the heater core. The only thing I found was a TR4 picture with a 45* street elbow and plug on the cylinder head which makes me think standard pipe thread.
Any ideas on correct US pipe or British "whatever" sizes?
Motor on!

 

[Geo Hahn]

...The only thing I found was a TR4 picture with a 45* street elbow and plug on the cylinder head which makes me think standard pipe thread...

That may have been mine you saw. It was shipped to the 'tropics' so it was sold new with the 'heater delete' package. I believe it is ordinary plumbing parts.

The hose fittings on the firewall were replaced with blanking plates.

The holes for the fan and heat valve got plastic plugs though mine have been repurposed for an OD indicator light and a kill switch.

 

[mastaphixa]

I don't have the exact sizes but they are totally stock plumbing fittings available at your local home supply store.

 

[TFB]

I believe the valve is 3/8 npt.
Personally if I had a problem and wanted to remove the valve I would run a bypass hose because I think it helps with the circulation for the rear of the head.
Tom

 

[Bremer]

I can confirm 3/8'' NPT for the back of the water pump housing. Not entirely sure about the port in the head, but it may be the same.

 

[jfarris]

I chickened out on dismantling the back of the water pump housing to determine the size and bought another valve, this one from TRF. With the many other sources, at one replacement every two years, I'm good for at least another 12-16 years.
Today, at Lowes, I confirmed the hole for the valve at the back of the head is 3/8" NPT.
Thanks Bremer for the water pump housing size, who knows when I or others may need it.
BEAUTIFUL driving weather down south all of the sudden - lows in mid 60s, highs in low 80s.