Use Chris Gould’s Nippy/65 book as a first point of call, but post any questions here that need answering for benefit of all.
on Nippy Head gaskets
A member sent Chris Garner an A7 Spares list from Witham’s Motors of Balham, dated March ’59. Under Gaskets, it lists the two types of head – thick and thin – at 4/6 each and a Nippy type at 10/- each. Thoughts?
from Chris Gould, Aug 2016: The Nippy did have a special head gasket because of the different combustion chamber shape. If the edge of the gasket protrudes into the combustion space there is a risk of it glowing red and causing pre-ignition. I don’t remember if this happens with the wrong gasket, there may just have been a gap where the gasket doesn’t reach the edge of the chamber. I think a low compression pre 1937 head gasket may work. A long time ago I had a batch of Nippy head gaskets made by Brian Harfield in New Zealand. I sold them all apart for one or two for myself. I don’t know if he has retired or if he can still make them.
Some images from Ian Williams show the Nippy head and the inconsistency with a standard High Compression head gasket:
Some other comparisons of the 3 gaskets:
Is anyone interested in purchasing a remade head gasket to Nippy specification?
The top one is a three bearing type; next is a two bearing Nippy cam and below that is a standard touring cam for comparison. Note the lobe shapes and the increased size of the front bearing. There is also a picture of a Nippy steel timing gear next to a std one, and Nippy centre roller bearing again next to a standard one. (thanks to Ian Williams)
Crankshafts and rods
Ian Williams writes “Below are pictures of Nippy and Speedy crank and rods; you will note how the Nippy rod is drilled above the big end and the Speedy one is not. You may also notice how small the drilling is in the Nippy oil pick up trough through to the big end. I believe that this is a large contributory factor for Nippys historically running their big ends. The pressurized crank has bolt on oil galleries to overcome the centrifugal forces that impede the oil flow down the length of the crank to the big ends. The drillings in the splash fed rods are less clear; some say they are there to allow the low pressure oil a route to escape, others that they allow another route for oil collection on the upward stroke of the piston.”
from the handbook: