TR2/3/3A cylinder head oil plug bolt size

[deuce]

I may have a problem...again. There is supposed to be a bolt plugging the oil galley at the rear of the cylinder head. My 1960 TR3a.. It's not there. Can anyone tell me the size of the bolt/plug. I was told it was 5/16-24. It's not.. 5/16 falls in and I can't get a 3/8-24 started. Help please. I seriously don't want to pull the head. There is only about 1 inch between the head and the firewall. Could it be Whitworth sizing? TIA

 

[charleyf]

I just pulled one out of a head. It is 3/8", course and 3/8" long with a copper washer.
Charley

 

[deuce]

Thanks, Charley

 

[bobhustead]

I just checked a spare head. The bolt is 3/8 coarse (as Charley said) and the thread pitch is 16. Not pipe plug thread, but NC bolt stuff. By the way, this plug closes a pressurized oil gallery that feeds the rocker arms. If you are currently running it and not gushing oil, there is some sort of plug in place. Check with a dental pick or the like as a probe and perhaps a mirror. If so, don't tinker or you will probably buy a head removal.
Bob

 

[deuce]

Yeah Bob..It was definitely pumping out. Thanks for the reply. It's a brand new engine. Fortunately, I looked down.

 

[mctriumph]

If some one left this out on a fresh motor, I predict you will find more leaks soon.
mad dog

 

[deuce]

Hope not!