Valve stem length,M 18 and 16

cf160 · Post by **cf160** » Fri Apr 06, 2012 8:35 pm

Does anyone have experience with the valves of the Post War iron heads
and is familiar with the valves? I have some NOS valves from that era , but some (smaller valve faced ones) are slightly longer than the ones with the larger faces. Smaller face stem length: 4.120" , Larger face stem length : 3.960" It is appx. one eighth inch difference. I think
the longer valves with the smaller faces are from the 350 cc head,while the shorter ,larger face ones are from the 500 cc head, but I would like some more knowledgeable opinions,please..
Dave(cf160)

dave16mct · Post by **dave16mct** » Fri Apr 06, 2012 9:15 pm

Your shorter valves should have a push on hardened cap which will bring them to the same size as the others.

cf160 · Post by **cf160** » Fri Apr 06, 2012 9:24 pm

Thanks for the info,David A. Do you know that I can get such caps from the Spares Dept.?
D.P.

dave16mct · Post by **dave16mct** » Fri Apr 06, 2012 11:22 pm

Russell Motors might have them.

itma · Post by **itma** » Fri Apr 06, 2012 11:40 pm

some even earlier iron heads have short stems, it is not specific to capacity.

cf160 · Post by **cf160** » Sat Apr 07, 2012 4:45 am

Do you mean earlier than 1946, Ken?
Is it really going to make much difference to the breathing of the head if the valve lift is 1/8th less?
The AMOC Spares do list the caps, although at almost
two pounds each...
D.P.

dave16mct · Post by **dave16mct** » Sat Apr 07, 2012 11:38 am

You won't have less valve lift, you're missing the point. You need the caps for the correct rocker/valve geometry, also for the hardenness of the caps. They fitted them for a reason.Edited by - dave16mct on 07 Apr 2012 10:39:24 AM

itma · Post by **itma** » Sat Apr 07, 2012 2:49 pm

wot dave said.

cf160 · Post by **cf160** » Sat Apr 07, 2012 7:07 pm

Oh , of course; it was late last night ... ,but were all the valves of that era so soft they needed caps or just certain years? The spares have the caps , but at four
pounds and change each. Curiouser and curiouser...
said Alice..