Rocker shaft education time. Nothing is easy!

[zyzzyx]

So, a while back I got a set of Crane Gold rocker arms gently used. I started thinking that I wanted a new set of
shafts that were very hard as the rockers are not bushed. Soft aluminum running on a hard slick surface is ideal.
Mancini has these shafts that are advertised as being hardened AND chromed. MRE715 Racing Chromed Rocker
Shaft. Pulled the trigger. Got em. Took a file to them and NOT HARDENED AND NOT CHROMED!!

Called them up and said "WTF"? They said, Oh Well! What I probably wanted was the Stanke Motorsports shafts that are hardened.
They also sell them at Mancini for $189.99. I called Stanke Motorsports and asked them about their shafts and the guy explained that
they are "Melonited". Being a retired Machinist, I had never heard of that process but would do some homework and find out. I Googled
"Melonite" and found that it was a another company's "Nitriding" process. 426 Hemi Cranks are Nitrided to a depth of about 0.004. Very
hard, about 75RC. Dat's what I want! I went back to Mancini and bought them. They're supposed to come today, so I'll report back.
Funny thing is, niether Mancini or Stanke Motorsports leaves this vital information out of their description! If the guy at Stanke hadn't
told me about that process being used on those shafts, I would have never known.

 

[zyzzyx]

Here they are! Harder than my new Nicholson file, straight, and they have oil grooves for the rockers!!!!
They measure 0.8724. Yeah, I can't touch the finish with a file, so they're pretty hard and will be good
for the soft aluminum rockers. Finally!

 

[beanhead]

Ahhhh yes....you get what you pay for strikes again LoL!
You're spot on, man. Mancini's basic shafts are made for stock rockers no matter what they advertise. The ones you posted look very nice!
I'm using Hughes shafts and they're good too. Banana grooved, threaded ends with plugs for cleaning and the proper finish for un-bushed aluminum.

 

[threewood]

Mancini has pissed me off enough times they are way down on the list of places to look.

 

[zyzzyx]

What I don't get is that no one has a correct description of what they're selling! You get it delivered
and they're either good or really really bad!

 

[Geoff 2]

The Mancini rocker shafts are hard chromed. Hard chrome is a very hard wearing surface. Crank journals that used up all the bearing under-sizes can be built up with h/chrome, & reground to spec.
It is NOT shiny like decorative chrome. Many valves have their stems flash chromed to improve wear characteristics, which is a thin coating of hard chrome. They are not shiny.
I would be using the chromed shafts if using alum rockers.

 

[Pedalpusher]

What I don't get is that no one has a correct description of what they're selling! You get it delivered
and they're either good or really really bad!

Been dealing with same issues with companies, (suspension & disc brake conversion)order takers, not knowing product, then leads to more out of pocket expense & time involvement other than finishing your build. Also lack of & or no instructions, torque ratings, missing pieces. I kept seeing Chinism on this forum, firm believer now! The products I have bought are well respected on FBBO.

 

[zyzzyx]

Geoff 2, sorry for the BIG RED X, but obviously you didn't read my previous post. Mancini's shafts are NOT chromed! That's my first pic. They say they are in the ad, but I bought them and had to return them. The black shafts are about 75RC, very hard and "slick".

 

[Geoff 2]

How can you tell they are not chromed? Hard chrome has a dull finish, looks like steel.
Have a look at some Ferrea valves. The stems are flash chromed with hard chrome to improve wear properties. They are dull.

 

[1 Wild R/T]

How can you tell they are not chromed? Hard chrome has a dull finish, looks like steel.
Have a look at some Ferrea valves. The stems are flash chromed with hard chrome to improve wear properties. They are dull.

Have you ever ran a file over hard chrome? It skates, it doesn't cut...In his first post zzyzzyx mentioned he ran a file over them..

 

[Geoff 2]

There is a reason the word 'flash' chroming is used. That it is because it is a very thin coating, once cut through you are into the base metal.
People confuse hardened with hard steel. You can drill hard steel with an ordinary drill bit, but you cannot drill a lathe tool which is made of hardened steel, tool steel.
The Mopar Perf shafts #P5249092 are listed as hard chromed, probably the same as Mancini is selling.

 

[rumblefish360]

The Mopar Perf shafts #P5249092 are listed as hard chromed, probably the same as Mancini is selling.

And there’s the worst word used in the hobby next to “Chinese” made, “probably”, which has me saying, a phone call is needed.
Ether you know for sure or you don’t. Probably is word when you don’t know. Your arguing on a premise of probability.

If you right or wrong it doesn’t matter at this point.
Seeking the fact(s) is.

 

[Dodge Bros]

We went thru the same thing. Mancini’s rocker arms come with the cheaper MR715. They are pretty soft, but seem to hold up ok on a SFT street and strip cam and spring package. The better MRESM715 is a good upgrade.

 

[padam]

There is a reason the word 'flash' chroming is used. That it is because it is a very thin coating, once cut through you are into the base metal.
People confuse hardened with hard steel. You can drill hard steel with an ordinary drill bit, but you cannot drill a lathe tool which is made of hardened steel, tool steel.
The Mopar Perf shafts #P5249092 are listed as hard chromed, probably the same as Mancini is selling.

Your statement doesn’t make sense.

If steel is hard, it’s because it’s been hardened somehow during the process. Granted some alloys are harder than others in the annealed state, but in the case of a lathe tool, it has been hardened.

 

[Geoff 2]

'Steel' gets it's various properties from the metals alloyed with it. Some steels are hard, like 4340 Chrome moly steel, but you can drill & file it. I call this hard steel. Two examples are the aftermarket oil pump drive & dist shafts.
What I call hardened steel, which cannot be drilled or filed are drill bits, lathe tools. And the factory oil pump drives.

 

[1 Wild R/T]

'Steel' gets it's various properties from the metals alloyed with it. Some steels are hard, like 4340 Chrome moly steel, but you can drill & file it. I call this hard steel. Two examples are the aftermarket oil pump drive & dist shafts.
What I call hardened steel, which cannot be drilled or filed are drill bits, lathe tools. And the factory oil pump drives.

Well perhaps you can explain what they are trying to say...

Pretty sure a file drawn across something that's hardened and chromed should skate over the shaft without cutting in... Unless your leaning hard into the file... And even then it should take some effort..

 

[padam]

'Steel' gets it's various properties from the metals alloyed with it. Some steels are hard, like 4340 Chrome moly steel, but you can drill & file it. I call this hard steel. Two examples are the aftermarket oil pump drive & dist shafts.
What I call hardened steel, which cannot be drilled or filed are drill bits, lathe tools. And the factory oil pump drives.

A drill bit is a good example. Now, I’m talking about a high quality general purpose high speed steel (HSS) bit.
The cutting end is hardened but the shank is not. If it spins in a drill chuck it will get burred up. But you can take those burrs off with a file.

 

[padam]

I took some pics of pages from a Crucible Steel handbook.

Crucible makes high end specialty steel, the top stuff is powdered metal (CPM.)

Back when I was in tool and die I used a lot of their steel. The grades will be similar from company to company, except for the specialty stuff. I use their book for reference because it has a lot of easy (easier for me) to understand info.

The first pic shows heat treating info for the HSS cutting tool grades. These would be used for lathe tools, drill bits, end mills, etc.

The typical annealed hardness is 230 Brinell which is around 21 Rockwell C.

For comparison a file is usually 57Rc.
The next pic shows heat treat info for select carbon and alloy steels. The AISI number should be familiar. These grades are real common for machine parts and aftermarket stuff, but not too much of our old OEM stuff used the 4000 series steels.

8620 would be a common gear steel, but I'm still not sure what MA Mopar used back in the day.

The interesting one for this thread is the Nitriding MO.135, which is a 4140 modified to be nitrided. I've included a couple more pages of info on that grade.
For reference, 940 Vickers would be 68Rc

 

[rumblefish360]

WOW! That was some cool pages posted on metal.
Thanks

 

[zyzzyx]

Thanks for that great info! We can understand what the process does.