Oil filler thread size

[BlownMGB-V8]

Anyone know the actual thread size and pitch of the opening in the Rover valve cover for the oil fill plug/flame arrestor/etc? I make it to be about 41.75mm and about a 2.25mm pitch but that is nowhere near a standard size.

Jim

[MGBV8]

No, but I can bring an oil filler plug to Townsend if it will help.

[Roverbeam]

1 1/4" BSPP
I bought a plastic (dummy) one from McMaster to test fit - it worked.

This site gives the thread specs, approximating Jim's metric measurements:
https://amesweb.info/Screws/bspp-thread-chart-calculator.aspx#google_vignette

Parameter   Value
Pipe Thread Size                    1 1/4
Threads per inch                     11
Pitch of Thread                        2.309mm
Basic Height of Thread            1.479mm
Height of Sharp V Thread        2.218mm
Major Diameter of Thread        41.910mm
Pitch Diameter of Thread         40.431mm
Minor Diameter of Thread        38.952mm

[MGBV8]

This thread gives the same answer as Chad, 1 1/4" x 11 BSP.

https://www.pistonheads.com/gassing/topic.asp?h=20&f=12&t=1425478&i=20

[BlownMGB-V8]

Figured it was something like that. Best price so far on a tap is about $47 which is actually quite fair really but a good bit to pay for a single use tool. Much cheaper and easier than making one though. Thanks all, and I will double check the thread pitch this morning. Should fit the 11 tpi gage perfectly I would expect. It should allow me some lattitude in configuring valve cover vents and such.

Jim