Valve and guide material compatibility

[tom3c75]

I?ve just received a replacement inlet valve from Slaters.    However, the valve is stainless steel and I am concerned about compatibility of the valve material with that of the iron valve guides.   

Seem to recall that there is a risk of valve seizure with a stainless exhaust valve in an iron guide.  Is this an issue on the inlet side as well?    I spoke to Richard about it and he advised me that there wouldn?t be a problem.     

Can I go ahead and use the valve in the existing guide?
Also, if I can, does the valve to guide clearance need to change or do I stick to the standard figure?
The exhaust side remains original, ie. cast iron guides with non-stainless valves.

Tom

 

[phil37]

Hi Tom - Not a good Idea to run a stainless valve in C.I. guide - It may be one I sold Richard - if so it has a chromed stem that is fine - Regards - Phil

 

[markQLD]

Can I go ahead and use the valve in the existing guide? 

wise men will say no.  Phil is correct, & Red would have the same advice.

however,

  I spoke to Richard about it and he advised me that there wouldn?t be a problem.

in 2002, i got a set of stainless valves from Richard and installed in the head of me Miss J ('81 Jota) with original iron valve guides.
& it's done over 50,000 k's without any problems.
<edit>  maybe the stems were chromed?  i dunno, but would suggest you ask Richard.
<edit 2> in fairness to Richard, i also got a set of bronze valve guides in the same order.  but didn't use 'em coz the originals were not worn to justify changing 'em, and another mate needed a set of guides at the same time.

but today,  i'd be listening to Red and Phil.
i have learnt the hard way, that one ignores Red's advice at one's peril !!
  lucky Mark

 

[Dellortoman]

I've got stacks of nylon bar here. I can turn you up a set of ultra-light plastic valves if you like. 

 

[IIS]

Constructed a test jig that measured the actual dimensions of factory valve guide and stainless valve stem,  from cold to upper temperature range,  graphed the results on a spreadsheet,  as individual parts and calculated,  guide to stem diametrical clearance. Post it here when i get home,  upshot was a critical part of the rising temperature had the clearance close to zero at one part of the slope towards normal operating temperature,  something under 200C or close to 120 perhaps, past that the clearance was acceptable

Had enough of wives tales about SS valves and produced my own clearance graph for Laverda heads,  no problem these last 10 years or more on SS valves.... hope that helps.  J.

 

[tom3c75]

Thanks for the info fellas.   

I?ve checked the valve and the stem does seem to be chromed: it has a different colour and finish.  Pic attached, but it?s not very clear.  I?ll check again with Richard, but he did say that he?d sold many of them and had no problems.   

John, that?s some research exercise you did and I?d be interested to see the table.

Cam, you?re an endless source of ingenuity, but maybe we should test your proposal using John?s method, no?

Tom