[Healeys] Camshaft differences

[Andy Thorp]

Hi Guys,

A while ago I read that there is a difference in early and later engines in that the cam has 13 vs 12 teeth on the gear that drives the oil pump. This supposedly coincided with the change from a lobe type to a gear type oil pump.

I have a mid 57 BN4, a late 57 Austin A105 sedan, an BJ8 engine and a Wolseley 6/110 Mk1 cam which are all interchangeable. The only obvious difference is that there are different ridges or grooves in the shaft between #5 cylinder lobes. The BN4/sedan engines have one ridge, 3000 engine has two ridges, 6/110 engine has three grooves, yet all of them have 12 teeth on the oil pump drive gear. Both the BN4 and sedan engines have a lobe type pump whereas the later engines have gear pumps. I have met one person who got caught by the different number of teeth on the gear when swapping a cam so the change must have been earlier on.

Can anyone decode the ridges on the cam?

Andy.
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