16H Tappet Guides and valves

The Spare parts list shows the same valves and tappet guides for inlet and exhaust....are the tappets different ? Has someone fitted a Big 4 part and altered something ? A photo would be useful.

The collet groove closer to the tip is characteristic of those fitted to the 1938 pattern enclosed tappet engines. They are austenitic and I believe not suitable for grease-lubricated iron guides. In my experience though, overall length is identical to the 1936 type. I wonder if the longer valve might be earlier ?

The manuals give a valve length from 'top of seat to tappet face' of 4.937" for both the 1936 type 16H and the '38 pattern Big 4 so the difference shouldn't lie there. 

I can't see that the nose length difference on the tappet guide would have any functional effect, but it might make one wonder about the quality control....that said, Norton's wartime WD 16H production had quite a lot of dimensional variation on non-critical parts. Time was of the essence. Most of the older spares around are ex-WD stock.

In terms of valves, personally I have given up on old stock...pattern parts have entered the market both home and abroad since the 1940s...it's impossible to tell the good from the bad. Top quality UK-made plasma-coated valves are available from G&S (Russells stock them, and probably others). They are superbly specified and finished.

http://www.gsvalves.co.uk/