norton dommie rockers same as commando?
- Thread starter baz
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baz said:
My guess is...
Wide rockers from 1949 up to around 66 when they changed to high pressure rocker feed and became the later narrow style.
The narrow style carried over into commando until the END.
and of course the shafts changed too at the same time.
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Dommy rockers are wider than Commando.
They did away with a lump of alloy inside the head where the spindle is supported on the outside end and so made the rockers longer to suit.
I assume someone (being very polite)buggered a few heads up when machining them so rather than scrap them they simply changed the machining drawings for the rocker forgings ....bit like when Norton buggered up a load of single crank wheels (long before WW2) and so as to make life easy and to save money they changed the big ends shaft diameter to suit and that is how it stayed to the end............
Its called Engineering in the UK which is why most of it died decades ago, with the help of short term profit and no long term future accountants and politicians (I tend to leave on letter out of accountant and get it correct ... doesn't half upset them just like referring to the Human Resources Dept. by the correct name of Personnel !!!
Example Dommy rocker exhaust right hand 18251. Not shown in my later supprsession list so no new Norton
06-**** number was issued so I guess they were no longer available.
Commando rocker exhaust right hand with ball end 06-2472.
They did away with a lump of alloy inside the head where the spindle is supported on the outside end and so made the rockers longer to suit.
I assume someone (being very polite)buggered a few heads up when machining them so rather than scrap them they simply changed the machining drawings for the rocker forgings ....bit like when Norton buggered up a load of single crank wheels (long before WW2) and so as to make life easy and to save money they changed the big ends shaft diameter to suit and that is how it stayed to the end............
Its called Engineering in the UK which is why most of it died decades ago, with the help of short term profit and no long term future accountants and politicians (I tend to leave on letter out of accountant and get it correct ... doesn't half upset them just like referring to the Human Resources Dept. by the correct name of Personnel !!!
Example Dommy rocker exhaust right hand 18251. Not shown in my later supprsession list so no new Norton
06-**** number was issued so I guess they were no longer available.
Commando rocker exhaust right hand with ball end 06-2472.
Its not uncommon to come across dommie alloy heads where the rocker shafts are loose in the head.
So its more likely that Nortons changed the design so that the shaft was better supported, with more of it in the alloy.
And the shaft would bend less if the rocker itself was narrower, and hence less flexing.
So there likely is method in their madness.....
So its more likely that Nortons changed the design so that the shaft was better supported, with more of it in the alloy.
And the shaft would bend less if the rocker itself was narrower, and hence less flexing.
So there likely is method in their madness.....
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