Hi
I am having a problem with a rocker intended for my restoration project ('64 G12CSR). As no new rockers are available as far as I know, I bought a used rocker off eBay which has indentation marks at the valve tip end.
Does anyone know the material used by AMC to cast the rockers? Is it cast steel or nodular cast iron? If cast steel, it will be case hardened. If cast iron, it might be a chill casting, in which local hardness is obtained by chills in the mold.
Rockers made of cast steel will experience plasticity (this seems to be the case here) and may be repaired by hard weld, but they need to be heat treated afterwards- this requires knowledge of the alloy they are made of.
-Knut
Twin rockers
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- Location: Vestland NORWAY
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- Member
- Posts: 373
- Joined: Wed Feb 01, 2012 1:22 pm
- Location: Vestland NORWAY
Re: Twin rockers
I had the idea to check the product announcement for the new twins (The Motorcycle, Nov 11, 1949). According to the article the rockers are made of forged steel with the integral tips being hardened (usually this means they are nitrided).
The wear pattern shows plastic deformation of the rocker arm tip in contact with the valve stem.
What this means is that rockers are salvageable by hard facing arc rod and grinding the tips to shape. If valve stem tips are stillited, the rocker tip hardness requirement is 50 RC. Do replacement valves provided by the club (e.g., 026041 or Alpha Bearings V205) have stillited stem tips? There is no information in the AMOC listing nor with Alpha Bearings. If someone has made the above exercise, please share your experience and procedure.
-Knut
The wear pattern shows plastic deformation of the rocker arm tip in contact with the valve stem.
What this means is that rockers are salvageable by hard facing arc rod and grinding the tips to shape. If valve stem tips are stillited, the rocker tip hardness requirement is 50 RC. Do replacement valves provided by the club (e.g., 026041 or Alpha Bearings V205) have stillited stem tips? There is no information in the AMOC listing nor with Alpha Bearings. If someone has made the above exercise, please share your experience and procedure.
-Knut
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- Member
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- Joined: Thu Jul 09, 2009 9:10 pm
- Location: CORNWALL UK
Re: Twin rockers
Hello
I had my rockers built up and reground by Newman Cams.
Regards
CAB
I had my rockers built up and reground by Newman Cams.
Regards
CAB
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- Member
- Posts: 373
- Joined: Wed Feb 01, 2012 1:22 pm
- Location: Vestland NORWAY
Re: Twin rockers
That's a good address, CAB. Thanks for sharing.
Did you specify an RC hardness, or have information from Newman as to which hardness of deposit they used? Have you inspected the rockers after some mileage and do they hold up well?
-Knut
Did you specify an RC hardness, or have information from Newman as to which hardness of deposit they used? Have you inspected the rockers after some mileage and do they hold up well?
-Knut