Triumph Screw On Valve Covers

[xxxchaindrive]

Does anybody know what size and type of threads are used on the valve covers and rocker boxes on a 67 Triumph 500. They are about 1 1/4" in diameter, and have 20 threads per inch. I had my rocker boxes chromed, and now the covers won't screw back in, so I need to clean them up.
Any help would be greatly appreciated.

[BTF]

1-1/4"-20 is a CEI size. (cycle engineers institute).

I did have a few taps at one point with that thread. Let me check and get back to you.

[xxxchaindrive]

I would appreciate that, I can't seem to find that tap anywhere. I can't even find that thread listed anywhere, not even on your site.
Let me know what you find, the sooner the better.

Thanks

[BTF]

We're in luck! :)

I do have one 1-1/4"-20 tap in stock. The cost is $105.00 plus shipping.

This of course, is going on the assumption that the thread you have given me is correct. Please double check as the tap is non returnable.

[xxxchaindrive]

I will measure the diameter of the cover threads, and make sure. I assume that when measuring bolt diameters on british threads, it is the same as measuring the diameter on an American thread. Like if I was to measure a 1/4-20 bolt in UNC, the diameter of the bolt blank would be 1/4 of an inch before threading, and slightly less after threading, due to displacement of the metal. Am I correct in this assumption? Also, could you tell me what the thread angle or pitch is, on the tap you have in stock?

[BTF]

You are correct. You should measure the shank of the bolt/screw.

The thread angle is 60 degrees on CEI threads:
http://www.britishfasteners.com/threads/cei.html

[roland521]

hi,i am roland ,nice to meet you