Help with thread size?

[Tow-Truck]

Hi All
I'm gathering parts for my freshen up and outside oiler conversion. I have the fitting that goes into the cam chest cover, it is a ninety degree bend with a thread on each end. The thread going upto the oil lines is an 1/8 NPT but the one going into the cover is a mystery to me. It is a tapered thread a tiny bit less than 3/8 in diameter and around 25 tpi (I've only got metric thread stuff here so the tpi is only approx.). I need to tap my cover for this so I need to know what size tap to buy, (we don't even use NPT here in England). I assume that the cover will be suitable for this modification?

[62pan]

Rather than modifying the cam cover, why not use where the oil pressure switch comes out of the oil pump? If you want to run a gauge or the idiot light you can just use a tee fitting. The cam cover certainly be used to oil the top end (they did it on Knuckleheads), but I would hesitate to drill extra holes in an original part.

The size that you have is probably 1/4" pipe, that is the size that was used on Knuckleheads.

[Purplepandan]

I am not 100% sure, but I think you need a 1965 cam cover to do that. You should probably do as suggested and come off of the oil pump. I have also done that mod using a Knuckle Cam Cover to oil '65 heads, but it was with an earlier bottom end.

[Hal64hd]

I am not 100% sure, but I think you need a 1965 cam cover to do that. You should probably do as suggested and come off of the oil pump. I have also done that mod using a Knuckle Cam Cover to oil '65 heads, but it was with an earlier bottom end.

Actually the cam cover from 63-65 used the outside oiler