Atlas / Commando head parts commonality ?

Am picking up a head and barrels for my bike, are the rocker arms, spindles and valves in the Atlas head interchangable into the Commando head ?, any differences ?.

Josh Cox said:

any differences ?

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I think that will depend on whether the head is early (pre eng. No. 116372) or a later one?

If it is an early low-pressure rocker oil feed Atlas head with scrolled rocker spindles, then you can't use the scrolled spindles with the high-pressure rocker oil feed.

The rocker part numbers are also different on the early heads-so you would have to check for any differences if it is an early head-unless someone else knows the reason for the part number changes?

The Atlas rocker arms were wider and won't fit into a commando head

Seeley920 said:

The Atlas rocker arms were wider and won't fit into a commando head

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But it would appear that the late Atlas rocker arms were the same as early Commando from Atlas Eng. No. 114870-on.

Late Atlas & Early Commando rocker part numbers were:

25332 Inlet R/H
25330 Inlet L/H
25336 Exhaust R/H
25334 Exhaust L/H

For 1971-on the rocker part numbers changed to:

http://www.norvilmotorcycle.co.uk/cylhead.htm

062471 ROCKER - RIGHT HAND INLET - ENGINE NUMBER 114870 ONWARD
062472 ROCKER - RIGHT HAND EXHAUST - ENGINE NUMBER 114870 ONWARD
062473 ROCKER - LEFT HAND INLET - ENGINE NUMBER 114870 ONWARD
062474 ROCKER - LEFT HAND EXHAUST - ENGINE NUMBER 114870 ONWARD

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Valves are very similar, they're the same diameter stem and head but a bit shorter. Difference in length is above the collet.

Result is they will fit but the adjusters will have to be further out.