I am in the process of refreshing the engine that will be going into my 240Z track car and I need to know the size of the plug to block off the heater hose tap at the back of the head. On the engine that is current in my car I have all of the coolant hoses deleted except for the rad hoses. I like this setup as it cools very well and minimizes the potential for cooling system failure at the track. To block the heater hose port at the rear of the head I am currently using a short length of hose with a metal plug and clamp. While I've got the engine out of the car I would like to remove this coolant fitting altogether and replace it with a plug installed directly in the head. I've searched here and on Hybridz and have not been able to find the size of plug I need to order. Some say it's a standard pipe plug and some claim it to be a british pipe thread. Anyone have experience with plugging this fitting?

I am in the process of refreshing the engine that will be going into my 240Z track car and I need to know the size of the plug to block off the heater hose tap at the back of the head. On the engine that is current in my car I have all of the coolant hoses deleted except for the rad hoses. I like this setup as it cools very well and minimizes the potential for cooling system failure at the track. To block the heater hose port at the rear of the head I am currently using a short length of hose with a metal plug and clamp. While I've got the engine out of the car I would like to remove this coolant fitting altogether and replace it with a plug installed directly in the head. I've searched here and on Hybridz and have not been able to find the size of plug I need to order. Some say it's a standard pipe plug and some claim it to be a british pipe thread. Anyone have experience with plugging this fitting?

When I got my 240Z three years ago it came with a brass bolt in it. A month back it started to weep so I thought I'd replace it. The store didn't have a sizer, but a 20mm seemed to match the diameter. The pitch, which I don't remember, alas, did not and I ended up wrapping the old one in teflon tape and reinstalling. So, it could be a 20mm with the pitch I don't have. Not real helpful, I know. I also seem to recall that I read somewhere that it's something odd like an American plumbing size. I couldn't tell you where I read that to save my life, but since I've never had a dream about plumbing, I likely did read it somewhere. Whether the source knew the difference between well, two different types of holes, I haven't a clue.

Chris

I know that the oil pressure sending unit hole is BSPT (British Standard Pipe Thread). I got an adapter from McMaster Carr for BSPT to NPT so that I could use a mechanical gauge. Looks like they might have a plug for the water hose port also. The hose is 5/8", maybe the hole in the block is 3/4".

How to measure is at the top of this page, along with some brass plug options - http://www.mcmaster.com/#brass-british-standard-thread-pipe-fittings/=f40iqn

I used a 1/2NPT plug from the hardware store if I remember correctly. However, I believe that most, if not all pipe threads in the S30 are BSPT, so I reluctantly used teflon tape. NPT threads are the same pitch but of a different shape, so an NPT plug will fit but likely not seal.

I order these and some "countersunk" allen hex key parts to plug the carb heater

http://www.amazon.com/gp/product/B002KLMJYM/ref=oh_o01_s00_i01_details

As you can see, the supply is pretty variable off amazon.

These look like good suppliers of this kind of thing. Make sure its BSPT (tapered) instead of BSPP (parallel). I'm pretty sure its all tapered threads. I think the countersunk would look a bit better, is cheaper, but probably harder to de-install w/o thread lube or teflon. Think brass would be better than steel.

http://www.amazon.com/IMPERIAL-96132-BSPT-STEEL-THREAD/dp/B001DENRKM/ref=sr_1_7?ie=UTF8&qid=1322409756&sr=8-7

http://www.discounthydraulichose.com/9030TCSP_BSPT_Countersunk_Hex_Plug_p/9030tcsp.htm

http://www.discounthydraulichose.com/9030T_British_Pipe_BSPT_Hex_Head_Plug_p/9030t.htm

http://www.grainger.com/Grainger/wwg/catalogPageView.shtml?Catalog=main&CatPage=4017 (see bottom left corner, brass!)

http://www.grainger.com/Grainger/wwg/catalogPageView.shtml?Catalog=main&CatPage=4017 (see bottom left corner, brass!)

Just noticed those "Chrome plated brass square head plug" parts. Those would look pretty good on the diff and transmission.

Outstanding! Just the information I was looking for. thanks guys.

I used a 1/2NPT plug from the hardware store if I remember correctly. However, I believe that most, if not all pipe threads in the S30 are BSPT, so I reluctantly used teflon tape. NPT threads are the same pitch but of a different shape, so an NPT plug will fit but likely not seal.

FYI:

Only 1/2" and 3/4" diametrical sizes have the same pitch (threads / inch), which is 14. The thread forms are different: NPT is the Sellers (60 degree-flat peaks and valleys) while BPT is the Whitworth (55 degree-rounded).