Board index Flathead Power-Technical Questions, Answers, and Suggestions Knuckles reworking knucklehead rocker arms

reworking knucklehead rocker arms

Post Wed Dec 07, 2005 12:09 am

Posts: 15
Location: Los Angeles Calif
Can anyone tell me where I can get my rocker arms reworked . The pads are worn and need to be repaired. Thanks

Post Wed Dec 07, 2005 4:48 pm

Posts: 919
Location: RENO,NV. U.S.A.
Have the worn areas built-up with TIG welding and dress up on a belt sander,also using KASENIT would help. MIG would definitely get the rockers too hot;KASENIT would definitely be in order. BREWSKI

Post Thu Dec 08, 2005 10:04 pm

Posts: 15
Location: Los Angeles Calif
Thanks Brewski,

I thought once the paws were built up with weld they had to be surfaced using a special jig to get the right angle , is this not that critical ? Thank again .


Post Sat Dec 10, 2005 3:14 pm

Posts: 919
Location: RENO,NV. U.S.A.
I have owned @ LEAST 9 SETS OF knuckle rocker arms,the angles aren't that critical for someone that knows what they're doing;on a belt sander!. That's why there is an adjustment on the lifters. BREWSKI

Post Sun Dec 11, 2005 11:28 am

Posts: 15
Location: Los Angeles Calif
Thanks Brewski ,

What type of rod should be used when Tig welded ? Ive never used Kasenit would that be the last process after the pads are shaped and polished ?

Post Sun Dec 11, 2005 8:02 pm

Posts: 197
Location: Bucktown, PA
Casenit would be last.
It's a case hardening powder that gives a 'skin' of hardened metal.
I wish I knew about it when I was throwing out all those 45 clutch throwout rods.

Post Sun Dec 11, 2005 8:47 pm

Posts: 3298
Location: Central Illinois, USA
I've got an old jar of "Kasenite", obviously not the original container, so I haven't the recipe for application any more. I have only used it over the years to flame onto agricultural blades and stuff.
Can anyone email me a set of directions for proper use? (Thanx in advance as always...Geez I hope my oven gets hot enough.)

And in reference to dressing the rockerarm pads,...yes it is just a matter of carving, but you really should have a second set to compare to, as you do it.
If you expected to do many, then a simple jig can be made to square it against a disc sander while you rotate it through its arc with your fingers: just a shaft installed into an angle plate sliding flat upon the sander table.

I suspect silicon bronze TIG'd on would be durable enough by itself.


Post Mon Dec 12, 2005 7:58 am

Posts: 648
Location: Wisconsin, USA
S&S included rocker repair info with install tech sheets that came with their cams many yrs. ago. Their suggestion was to weld the contact area on shovel rockers with mild steel rod and a TIG. Most shovel rockers have a shallow surface hardening that goes away quickly. The contact surface has to be ground parrallel to the rocker. Trock Cycle makes a tool for 57up XL+ Shovel rocker regrinding. I use the same procedure, but I use the knuck shafts with their respective rockers on V-blocks. Use a small diameter ginding stone mounted on a mandrel in the drill press. The V-blocks are clamped to the drill press table, centering the contact surface under the wheel. A light spring is fastened to the ball end to force the contact surface towards the stone. As you move the stone up and down you try to maintain the original contour, which is there to provide minimal contact with the valve as it moves across the stem face. The pad surface all of the HD rocker arms I have reground was parallel to the shaft /arm. Any deviation is probably the result of error. Please remember that HD machinists had tolerances. In a perfect world, the valve guide hole in the head, the guide to stem hole, the holes in the head and rocker box to mount the shaft, would all be exactly located to provide a true right angle to the valve. It seldom works out that way. The worse it is, the more you find the rocker being driven to one side or the other on its shaft.
Last edited by amklyde on Tue Dec 13, 2005 8:09 am, edited 1 time in total.

Post Mon Dec 12, 2005 10:25 am

More or less:
"To surface-harden low-carbon mild steel parts.
The powder is absorbed into the outer surface of the part, and chemically hardens only the surface. The interior of the part remains as fatigue resistant as it was, for maximum toughness.
To use:
1. Clean the part you wish to harden with hot water & detergent, alcohol, MEK, or acetone. Don't use kerosene, Safety-Kleen, or gas - they leave a residue that will interfere with the hardening process.
2. Heat only the area you wish to harden to bright red with a torch (1650 Degrees Fahrenheit).
3. Dip the hot end into the powder and roll around to coat it completely.
4. Re-heat the area to bright red immediately.
5. Quickly immerse in cold water; stir the part rapidly in the water to insure even cooling.
To increase the depth of penetration, repeat Steps 2 & 3 before quenching (in other words, give it a double dip of powder).
To increase the hardness, repeat Steps 4 & 5 (quench it twice)."

Post Mon Dec 12, 2005 11:14 am

"The contact surface has to be ground parrallel to the rocker"

Not sure what you mean.
The tip radius (in theory) is a very complex issue.
1. a simple radius
2. an evolute cycloid curve, which is formed by a circle "rolling" across a flat surface.


Not sure if this is true - found different opinions on this, don't take it as gospel!
Last edited by panic on Mon Dec 12, 2005 3:02 pm, edited 2 times in total.

Post Mon Dec 12, 2005 2:01 pm

Posts: 51
Location: Maui, HI.
Knuckdave 41,

I had my 1941 set of rocker arm pads reshaped by Lee @ Lee's Speed Shop. He has made a jig for the proper angle and specializes in Knucklehead work. Hope this helps.

Post Mon Dec 12, 2005 8:30 pm

Posts: 3298
Location: Central Illinois, USA

Your Kasenite info was most appreciated!
(I was almost doing it right!).

Now, on to the arc of the rocker pads:

I was told (by someone I respect) that the pads were intentionally angled on the lateral plane to facilitate rotation of the valve.

(Hmmn..... maybe?)

And that regrinds were always off anyway, so much the better.


Can anyone substantiate this?

Next question: Why do so many Pans have two arcs on the rocker pads?


Post Tue Dec 13, 2005 8:23 am

Posts: 648
Location: Wisconsin, USA
Sorry for the delay in finishing the reply above. My keyboard just up and quit in the middle. I forgot to mention something to look for when refinishing Knuck rockers. Knuck rockers have a "short" pad that ends in something like a 90 degree angle at the far side. If you have a head with good seats and are using one of the shorter than stock aftermarket valves, with a high lift cam, you can exceed the pad and end up with the sharp edge at the 90 contacting the stem face, and worse case, getting somewhat "over center". All the components in the valve train get stressed out in this scenario. Its always a good idea to check out the contact at your cams lift with the cover off and a light dummy spring intalled in place of the valve springs so you can easily move the rocker.

Post Tue Dec 13, 2005 9:18 am

I still haven't tracked down how the pad curve is generated, but it looks like between Miller ("mid-lift" rocker theory) and the geometry re-surfacing the pad at the proper angle is a partial fix, but:
1. it does not restore the rocker to new condition since some metal is removed.
2. adding weld etc. back to original size is preferred but probably not needed for mild apps.
3. the exact position, and the exact radius of the pad curve, and the height of the rocker and shaft will be different if the cam lift changes. Not enough to matter in a mild cam (IMHO) but a race motor needs this stuff spec'd. out, and I doubt that anyone (except Hill?) ever did.

Yes, this would also be true of other pushrod motors.

Post Tue Dec 13, 2005 12:04 pm

Posts: 15
Location: Los Angeles Calif
1937ulh thanks , where is Lee`s speed shop located and how can I get in touch with them . Thanks Again .


Post Wed Dec 14, 2005 12:53 pm

Posts: 51
Location: Maui, HI.
Knuckledave 41,
Just type in leesspeedshop in your search engine and it will come up. He's worth contacting. 1937ulh

Post Mon Dec 19, 2005 2:57 pm

Posts: 919
Location: RENO,NV. U.S.A.
KYLE,what are the 'CORRECT" angles???????????? Like I said anyone that knows how to use a belt sander!!!!!!!!!! COULD DO THIS!!!!!!. In my personal opinion; MIG WELDING IS FOR PEOPLE WHO CAN'T WELD!!!!!!!!!!!!!!!!!!!!!!!. I WOULD LIKE TO KNOW THE ANGLES YOU'RE TALKING ABOUT. AS I OWN SEVERAL NOS KNUCKLE ROCKER ARMS. BREWSKI

Post Wed Dec 21, 2005 8:11 am

Posts: 648
Location: Wisconsin, USA
Hey Brew, I was just refering to the very far end of the rocker pad, there is a flat ground nearly perpendicular to the pad surface. Pan and later rockers, have a "longer" contact surface and there is no other machining at the forward edge. I was just trying to point out, that if you are working with shorter than oem length valves (Kibblewhite,Import and old Rowe) and new or very good seats, with a cam that has an additional .100 or so in lift, the sharp edge where the pad contour meets the flat will be the only contact with the valve. I'm sorry I'm not very good at explaining this stuff. I write descriptions from a picture in my mind, but I think it is much harder for someone to read my description and form the picture in their mind.

Post Wed Dec 21, 2005 5:30 pm

Posts: 919
Location: RENO,NV. U.S.A.

Post Tue Mar 08, 2016 8:14 am

Posts: 70
Does anyone have actual experience using Kasenit on rocker arm tips? I need to decide whether to use a case hardening compound or to weld build up with a hardsurfacing wire such as drill rod.


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