Are stainless valves harder on stock iron head seats?

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340doc

340doc

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Doing a set of 2.02 J heads, and some stock valves are questionable. I was considering a stainless set, but started wondering if the stainless valve would be harder on the stock seat in todays unleaded world. Car is a weekend driver with 500 lift Hyd cam, so more spring pressure than stock.
 
Waiting for more experienced replies but... I believe stainless valves are actually easier on the seats, stainless steel alloys are almost always softer than non-stainless. That's why you don't see it used in engines very much.
 
MopaR&D said:
Waiting for more experienced replies but... I believe stainless valves are actually easier on the seats, stainless steel alloys are almost always softer than non-stainless. That's why you don't see it used in engines very much.
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Interesting, I always thought it was harder. So much for that, lol.
 
340doc said:
Interesting, I always thought it was harder. So much for that, lol.
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Nope definitely not, actually I was just reading around apparently engine valves aren't even made with "true" SS because it's too soft, it's a specialized alloy with just a teeny bit of chromium to make it "stainless". Also you should look at hardened seats regardless of what type of valves you go with.
 
MopaR&D said:
Nope definitely not, actually I was just reading around apparently engine valves aren't even made with "true" SS because it's too soft, it's a specialized alloy with just a teeny bit of chromium to make it "stainless". Also you should look at hardened seats regardless of what type of valves you go with.
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Good to know
 
The induction hardening on the early stock iron heads is little more than a surface treatment, a valve job will usually remove it. Hardened seats are always a good plan when the valve seats need cut.
 
Thanks, I'm aware of this but still wondering if a SS valve is harder on the stock seat than the OEM valve
 
There are many grades of stainless. Some are soft, some are very hard. Most stainless bolts are soft and will ring off easily. I have some stainless plates that are so hard you cant drill or cut it without annealing first. So it really depends on the exact type of stainless they are made of.
As far as your question, I really dont know. As mentioned, its probably pointless to go stainless if your running stock induction hardened seats. At minimum you should put hardened seats on the exhaust side since they take more of a beating.
 
Aftermarket Stainless valves on factory seats is a great idea. They're all some sort of stainless alloy, remember that's a % combination...
 
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Hardened seats will last a long time but standard seats will probably be fine for at least 30,000 and probably more miles which most muscle cars will never see.The hardness depends on the amount of chromium and nickel added and the carbon content of the parent metal to make it stainless.So stainless can be soft or hard.
You can spend a lot of money building these cars and you can also build economically.
 
I've said it before and I'll say it again--Stainless steel valves will stop exhaust valve seat recession which will negate needing hardened seats installed in your J heads. I have witnessed this many times. Valve seats "sinking" or becoming recessed is due to little chunks being ripped from the seat every time the valve opens-kinda like everytime a sparkplug fires a "chunk" of electrode is removed. Stainless alloys seem to stop the fusing and "ripping" of the exhaust seat thus stopping the recession. Iron and Stainless get along very well. J.Rob
 
I looked through hardness numbers for both they are not far apart. As indicated above in a couple of posts, the normal use of hardness numbers (removal of one substance by another in a rubbing or grinding motion) is not really the issue, especially if the valve set up is not rotating the valves which was done to keep lead from building excessive lead oxide deposits on older engine designs.

IMHO, it is matters like the heat levels and softening of the seat that are the issues. The transfer of material idea above is a pretty interesting observation too. Plus in a performance engine, controlling the valves well with the spring selection to avoid valve bounce seems like it would be critical.
 
All the stainless valves I've used ar 21-2n... never a problem but that's only in 3 or 4 engines.
 
What RAMM said
Mopar heads are harder than chevy/ ford etc
so usually stainless works just fine
and MOPAR motorhome valves are even more premium- exhaust may be Inconel
that said I put in the premium Dura Bond sintered seats in most of my builds especially trucks/ motorhomes
put seats in if your seats have any rescission
if not they are work hardened
on the valves
you have to match the valve stem materiel and finish to the guides
unplated stainless valves- the budget ones act like files I OD hone them
I prefer hard chrome valves to flash chrome ones
I use the spiral grooved guides and even knurl and ream NEW guides then hone to give some oil retention
Unleaded is here to stay
and center two exhausts run HOT
Viton stem seals
 
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