cylinder head ID - commando 1970

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Aug 26, 2005
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I am looking for info to ID the correct head for a 1970 roadster.

I found the info below - Is this accurate ??? Where can good info on this be found?

TKS!!!!
 
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Aug 26, 2005
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info found

the intake ports it will tell you what year.

28mm up to 1970
30mm 1971 1972
32mm usually they have a C stamped on the top for Combat, higher compression and 32mm intake ports
850's have RH 4 or RH 10 over the right exaust rocker box, 4= 32mm 10= 30mm
 
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Aug 26, 2005
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That's interesting, I wonder what year the 28mm head was from, and if it will work on a 70???
 
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Aug 26, 2005
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Tks for the link - I had a look, great info source!

The site doesn't refer to the 28mm port head, so I'am still unsure about putting this head on my 70???
 
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Apr 15, 2004
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My 71 Roadster has 28 mm ports.

Who knows if that's the original head though :roll:

Debby
 

Ron L

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Port diameter

Norton twin port size is 30 or 32 mm measured at the intake manifold. Some heads neck down to 28 mm after the intake manifold connection.
 
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