Is case hardening enuf?

[angus67]

I've read in posts that mikexs valve adjusters aren't hard enuf, and quickly mush up.
I had a original adjuster back out on my 71, and had a spare motor to salvage from. Back on the road in no time.
I purchased a replacement tap pet from mikesxs, and wondered if case hardening would help at all?
I have made homemade hammers and stuff, and heat them to red hot, and qwench in used motor oil to harden them up.
Just curious if this could be a cure for soft tappers? Or will it fuggle the threads?

 

[fredintoon]

Hi angus,
if mikes lifters have a high enough Carbon content to be hardenable, your described technique will get them glass hard throughout and too brittle to stand up in use.
If they don't, they won't be improved by it.
What you describe is not case hardening.
Case hardening is the process of taking a part made of steel that has too low of a carbon content to be hardenable, packing it in a steel box of carbon-rich powder such as powdered bone or charcoal or one of several patented case hardening compounds and heating the box red hot so the part's surface takes up more carbon and then removing the part and oil quenching it while it's still red hot.
This gives the part a hardened skin and leaves the core still soft and tough.
So yeah, pack carburizing will harden a soft lifter but the threads will be hardened too.
What I reckon is, learning the process and buying the oven will cost way more than buying those high priced Porsche swivel footed lifters.

 

[jonesey]

G/Day Angus
You could try the tappets from an XT 500 as I had some missing tappets a while back and here in S.A. you very often have to use alternative parts. The TX 750's are the same too but most of the listing for the TX is now obsolete for obvious reasons.
The Valve stem seals are the same as well.
If in doubt use the original parts or at least something for the same function design wise.
Fred's desciption is spot on and I think the case hardening medium is called Casenet, I have'nt done that since my apprentiship days but the depth of hardness is only a few thou.

 

[Higgy]

After making custom knives for a living, I can tell you that hardening/tempering is all about time and temp. You have to know exactly what grade of steel your valve adjusters are made of, and follow the correct recipe for hardening to a specific Rockwell hardness reference point in order to get enough hardness AND toughness to be durable.

I am holding on to the opinion that if you are Burt Munro, then go for it. If not, it is probably not worth the time and effort.

 

[angus67]

Thanks guys. Perhaps homemade tools qwenched in oil is fine, but something that takes a beating like a tappet isn't good enuf. I'll try to find a original tappet for my spare motor. No hurry.m
Thanks again.