Valve sizes

1608 · Post by **1608** » Mon Oct 08, 2012 5:46 pm

Can anybody tell me the valve sizes please for a 1958 18S, and are they both the same size. O/A length, stem and head Dia. Couldn't find anything in the archives.
Thanks

Rob Harknett · Post by **Rob Harknett** » Mon Oct 08, 2012 6:15 pm

350 & 500 are the same it seems, I'm sure the exhaust valve has a larger head. Perhaps someone has some handy to measure. Beware smoe look the same but stems differed on older types, some older types used caps which mademade stems longer.

1608 · Post by **1608** » Mon Oct 08, 2012 9:24 pm

Thanks Rob, you must be a mind reader. I have robbed a 350 head of valve gear for when I need them later on.

56G80S · Post by **56G80S** » Fri Oct 19, 2012 10:36 pm

I recently replaced the valves (and guides) on my 1956 G80S. The replacements were identical in size. I understand that there was a difference in material for the "originals" but now the ex valve is often used for both.

For example look at the Surbey's parts / price list at AMC Classics.

Bike is going well but do need to re-jet as running rich now I've finally fitted an air filter (but there's loads of other threads about all that!).

Johnny B