how much hardening on typical valve stem tip?

[rewguy]

case in point, LS1, engine quest black performance valves. how deep is the hardness for stem trimming purposes? I to E is different but consistent. Exhaust seats were cut for 1.55 valves, but out of necessity am using 1.570 valves. seat heights are consistent.

[modok]

Don't know specifically, if those particular valves can take more or less.
As a general rule I won't remove more than .015-.020 from a valve with a hard tip insert.
Can measure keeper groove to tip to see how much it has been ground if you have a new one to compare.

[mag2555]

Before we even go to trimming the stems, what is the stem height difference between your new Exh valves and the Intake valves, and are you still using hydro lifters?
If you have hydro's and your stem height difference is .030" or less I don't know that I would do a thing!

[Newold1]

The black nitriiding of the valves is a great process for valves. It is called QPQ ferretic nitriding, but it is only about .003" into the stem and on the tip of the valve that already has a hardened tip. For the .010" to .015" you are trying to achieve I think it is probably best to just machine the valve spring pockets for that slight additional height you are looking for. JMO

[jarmoyp]

Newold1, I think he is not asking the spring height issue.
I make the rehardening after tip height modification, it has been good but you never can be sure..

[Walter R. Malik]

If a valve tip is pretty beat-up, it is probably near through the end of the hardening already.
If it is simply cupped or not flat anymore just tip it only until it is flat.

[pdq67]

Can he clip them down and then use valve lash caps?

pdq67

[Walter R. Malik]

Can he clip them down and then use valve lash caps?

pdq67

That is one way of getting around it, as long as it is not a hydraulic valve train.