Cylinder head studs

Does anyone know off the top of their head what the threadform is of the two front studs extending down from the cylinder head? I was tightening them down last night and apparently gave one a little too much snot and stripped it out. I'm just wondering if it's locally repairable (standard) or if it's a good excuse to send it off to CNW and get some other head work done (Whitworth).

It's a pretty common occurrence to have the studs pull out with less than specified torque. I replaced mine with 3/8" studs. 24 tpi on one end and 16 tpi on the other. That way you can use a commonly available 3/8-16 Helicoil. Of course, you have to replace the nuts with a suitable 3/8-24. I know this offends some Norton purists, but any time I can I replace the Whitworth fasteners with commonly available UNC or UNF fasteners. It's a lot easier to go to a hardware store to replace a fastener than wait for a supplier to send one, not to mention a lot more cost effective.

As I recall, the studs are 3/8-20 by 3/8-26. The problem with using 3/8-16 by 3/8-24, commonly available studs sizes in the US, is finding long 3/8-24 nuts to fit. You can make your own from hex bar stock in a lathe. You can also drill out the stock Norton nuts in a lathe, and install 3/8-24 inserts in their ends. An easier solution would be to hunt up Recoil brand inserts (Australian copy of Helicoil) in the proper size to repair the head. I know they are available in 3/8-26, because I've used them. I assume they are also available in 3/8-20, but don't know that for sure. It's worth checking. Putting inserts in the head is certainly the most straightforward solution.

Ken

lcrken said:

I know they are available in 3/8-26, because I've used them. I assume they are also available in 3/8-20, but don't know that for sure. It's worth checking.

Click to expand...

3/8"-20 (BSF) = Recoil kit 30060

http://www.buckandryan.co.uk/product.ph ... n/RCL30060

Also available on this side of the pond at:
http://www.britishfasteners.com/mm5/merchant.mvc?Screen=CTGY&Store_Code=BTF&Category_Code=344

OOPs! Wrong page:
http://www.britishfasteners.com/mm5/merchant.mvc?Screen=CTGY&Store_Code=BTF&Category_Code=342

Please keep original thread and nut size for next owners sake unless you make a big label.


Russ