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Cylinder head identification assistance

Submitted by steve_adkins on Sun, 07/10/2012
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Heavy Twins
I have just purchased a bare alloy head from our annual swap meet. Its for a spigot barrel and has a cast-in mark reference of 22707 M appears (in fading light) to have 1 inch inlet port and 1.25" exhaust. Any idea what this is originally off and what models would be a 'compliant fit?' Thanks. Rgds Steve

Submitted by eugene_brolund on Sun, 07/10/2012

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Hi Steve,

here is a great link to Dave Comeau's website "AtlanticGreen", this shows a bunch of Norton twin heads & how to identify them.

Skip

Submitted by benjamin_gradler on Wed, 10/10/2012

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Just so people are not mislead yet once again by a thread here:

The casting number 22707 appears on the top of the non-SS Model 88 and Model 99, non-downdraught cylinder heads used on the first few years of the slimline roadsters.

Yes the same casting number appears on the top of the early 650cc cylinder heads used on the Manxman and 650ss which does have the downdraught intake ports, a design used with minor alterations all the way through to the last Commando in the mid-1970s.

The intake ports on the 650cc heads measure 1 1/8" stripped bare but in practice they were used with steel sleeves pressed into the ports to reduce them by 1/16". If your cylinder head actually does have intake ports that measure only 1" then it is not for a 650ss but for one of the smaller capacity twins....

 


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