I've been given the task of making some new valve stems for a friends engine and I've read on various forums that they use stainless steel bar now there are three types listed which would be the most suited for this application? 303,304 or 316 i understand 316 is used in a high corrosion application but would this be easily turned? Many thanks Gaz
Gary, All the washing equipment my company builds is with 306, if we have to drill it it is a Ba'stard as it work hardens at the hint of heat I am assuming that 316 is even harder, to get a decent finish will be your hardess task, I would go for a lower grade so you can machine it but still be tough, by the way there are 150 grades of stainless also I told you I would forget, I will check my valves tomorrow. Martin P
Cheers Martin I did forget myself would you suggest something else or use plenty of suds when machine to reduce heat build up? Thanks gaz
Gary, Sharp tool lots of coolant, are the old stems stock size, you maybe able buy stock sizes. Martin P
Why make work? If you are only making stems then its probably a low stress engine or even H&M. A decent grade of mild or even silver steel should do the job. cheers Roland
Hi Roland I was of the understanding that silver steel would work harden and become brittle? Would bright steel bar be ok for the task and it's a lister L sorry should have mentioned that earlier. Cheers gaz
HI Gaz, We use all the above grades at work and I can say for turning, 303 is the easiest, although 316 gives the nicest finish. I would suggest using an insert tool for best performance but HSS will turn it. Good positive angle and rake, sharp point (0.4mm rad max), plenty of coolant, not too much speed. We use CNMG type inserts. Your biggest problem will be keeping it parallel, as the cuts get smaller, there is greater chance of the tool pushing off and not cutting. As Roland says I'd make things easy and go for ground silver steel bar. HTH Mark
Don't forget if you weld silver steel it is a medium carbon steel, you can use a 316 rod but will need to heat treat after welding You can use a stainless like 431 martensitic ideal for pump shafts etc will machine ok as for ordinary s/s , then take to red heat (1050C) air cool and hey pretsto a 500 vickers hard valve and not brittle (aka knife stainless) Malcolm
Gentlemen, What bothered me when discussing this with Gary when I visited him before Christmas was the fact that Silver Steel can be very heat sensitive, he is going to replace the complete stem from the neck of the valve and this bit sits at the hottest point when the valve opens to release the exhaust gases. If he doesnt get the heat treatment spot on it could very easily snap and over time it will be heat treated every time it runs which I think will weaken the joint. Martin P
Hi, I dont like the thought of a welded joint between valve and stem, worse with dissimilar metals involved. Why not make new valves complete? Regards, Harry
I'd agree. I'd have thought a shoulder and peen or thread and peen would be sounder. Martin - surely the heat-cycling will keep the stem annealed? Whatever I'd much prefer to buy o/s valves and turn them down. Loads on Fleabay Worth also saying that when the L was first made none of these fancy steels existed and valves were "Best mild steel". Even just prior to WW2 EN20 (high nickel steel - no modern equivalent) was about the best available. Aero engines were beginning to use KE965 and other Nimonic steels. As always I'm happy to be proved wrong. cheers Roland
I dont think the valve would be heated enough to be annealed, I like the idea of thread and peening this would move the join further up away from the hottest temperature. Martin P
Another possible solution often used many years ago or not so many was a basic mild steel valve with a stellite welded on edge to stop burning at the seat. On a serious note carbon steels ought to be avoided unless correctly made most used to forged, (been there done it) if the engine isn't to to worked hard then a decent mild steel would suffice, many years ago I ran a Fowler at full load which had M/S valves- they did not last but on light load were perfect. So look at what you are going to do with yuor engine and manufacture acordingly.
I would agree there but I would try to match the head size as close as possible. You could still add metal to the end of the stem if its short and the joint will not be in the critical part then. Would others agree that it would be better to go for old stock imperial valves rather than modern ones because the material might be a lesser grade and therefore easier to machine? Mark
Hi guys, When I took this project on this seemed like the easiest route to take make new valve stems thread,peen and some silver solder just in case. I much prefer the idea of buying over sized valves but it all boils down to cost ( I haven't checked prices as of yet) another idea which I think Paul mentioned once when we was down at IF was to build the worn stems up with weld then machine back to standard? But would this need to be ground or turned on the lathe? I could then machine the valve stem over size and fit a bush/sleeve ( this engine for some strange reason has no removable valve guides which all my others do) The engine is going to be a part time show engine and the other half working hard cutting fire wood. Cheers and thanks for all your help gents Gaz
They're probably far too big for what you need, but currently new valves for Series Land Rover engines cost peanuts... http://www.paddockspares.com/parts-and- ... etrol.html I'd imagine cutting an oversize valve to size would be far less work than turning, threading, soldering etc new stems for old heads.... and probably more reliable in service.
Just been out to the workshop and I have some nos lister cs valves which are the same diameter as the L but are too short and the head size is a lot smaller.... Measurments of the old valves are Stem: 11.52mm Length 183.0 mm Valve diameter 53.78mm Could anyone cross reference these numbers to a valve I can machine down? Cheers gaz
