Rocker Shaft Orientation

L.A.B. said:

Dunstall tuning notes say that the earlier narrow gear pump was "the better unit for racing..." but modified to take the wider later pump scavenge gears.

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olympus said:

Reference is made here to 3 start & 6 start gear.???..I take it this is to do with the gearing ratio of the pump & crank scroll gears. ?

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Andover Norton - CRANKSHAFT WORM GEAR, 6-START, 1966-ON (NM24732) - 06.7889

CRANKSHAFT WORM GEAR, 6-START, 1966-ON (NM24732)

andover-norton.co.uk

dynodave said:

late pump gear width-feed.250"/scavenge.416" (measured .401.406.412) feed-scavenge ratio 1.666

early pump gear width-feed186"(3/16")/scavenge.312"(5/16") feed scavenge ratio 1.666

dunstall
early pump gear width-feed186"(3/16")/scavenge .416" feed scavenge ratio 2.236

I own only one early narrow oil pump. It is a zinc/potmetal body. Did they make narrow gear iron ones?

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