Norton Commando Cylinder Heads

Curiosity question regarding Norton Commando cylinder heads. The NOC site provides the link below, where 10 different CDO head options are described.

http://www.nortonownersclub.org/support ... tification

My questions in this regard are the following.

1. How many different castings were employed to create these heads?

2. Were unique castings required for the specialty heads, e.g., RH2, RH7, RH8, RH9?

I’m curious about the castings because I was wondering if all of the heads could be created from a single “standard” casting, or if specialty castings were required to accommodate certain port placement, port dimensions and attendant guide support, etc. Thanks in advance for any insight on the subject.

The big valve heads are not from special castings, just different machining on the standard Commando castings.

Ken

As far as I know two castings were used on the Commando. One for 73mm bore engines and a different one for 77mm bore engines. I suspect they also used a couple different core pieces for 28 or 32mm ports.

I am sure there were also small changes made as the casting molds were replaced over the years. Jim