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Combat head

Classic Norton Commando Motorcycles.

Combat head

Postby pierodn » Fri Sep 08, 2017 1:17 am

Hi.
Do you mount to the combat head the valve spring insulators?.
Thank you.
Piero

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Re: Combat head

Postby bill » Fri Sep 08, 2017 4:41 am

yes but only on the exhaust side.
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Re: Combat head

Postby pierodn » Sat Sep 09, 2017 11:13 am

bill wrote:yes but only on the exhaust side.

Hi.
Thank you.
Please, why not on inlet side?.
Piero

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Re: Combat head

Postby kommando » Sun Sep 10, 2017 12:56 am

Because the extra lift on the cam will give bind in the valve springs.
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Re: Combat head

Postby batrider » Sun Sep 10, 2017 6:40 am

I remember a service bulletin for the Combats that mentions checking that the lower valve spring cups (the ones against the head) sit flat against the head. The outer edge of the machined surface for the valve spring cup in the head has a radius but the cup has a square edge so it may not sit down all the way. Back then I had a machine shop modify my spring cups by rounding off the square outer edge.

Good luck with it Piero. I just found a listing of all the service bulletins.
http://www.eurooldtimers.com/cze/manual ... mando.html

It is Service Bulletin N2/3 from April '72. Also has the info about the insulating washers.

Russ
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Re: Combat head

Postby oldmikew » Sun Sep 10, 2017 11:47 am

kommando wrote:Because the extra lift on the cam will give bind in the valve springs.


it will make the springs coilbound...that is the danger... possibly by a judicious slimming of the bottom steel cup and using the later heat insulators that were thinner . you might get away with it... you could have the head machined so there is the requisite clearence.. surely not a difficult operation. whatever you do assemble and turn the engine over to make sure they are not coil bound . even without the insulators some bikes left the factory in that condition
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Re: Combat head

Postby oldmikew » Sun Sep 10, 2017 11:53 am

batrider wrote:
Good luck with it Piero. I just found a listing of all the service bulletins.
http://www.eurooldtimers.com/cze/manual ... mando.html

It is Service Bulletin N2/3 from April '72. Also has the info about the insulating washers.

Russ


Many thanks for posting the oldtimers link
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Re: Combat head

Postby pierodn » Wed Sep 13, 2017 1:25 pm

batrider wrote:I remember a service bulletin for the Combats that mentions checking that the lower valve spring cups (the ones against the head) sit flat against the head. The outer edge of the machined surface for the valve spring cup in the head has a radius but the cup has a square edge so it may not sit down all the way. Back then I had a machine shop modify my spring cups by rounding off the square outer edge.

Good luck with it Piero. I just found a listing of all the service bulletins.
http://www.eurooldtimers.com/cze/manual ... mando.html

It is Service Bulletin N2/3 from April '72. Also has the info about the insulating washers.

Russ

Hi Russ,
thank you.
Piero

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