Page 2 of 2
Re: block identification
Posted: Fri Sep 17, 2021 3:15 pm
by dudload
probably a poor description, but the 1098 head didn't have the large "clips/circlips" on the top of each valve stem, per this link:
https://www.morrisminorspares.com/engin ... s-p1238983
the old head had what i normally expect to see, per this:
https://www.morrisminorspares.com/engin ... s-p1238985
Re: block identification
Posted: Fri Sep 17, 2021 5:54 pm
by philthehill
Thank you for the explanation.
BMC ditched the spring circlips holding the valve stem cotters together as there was no benefit in keeping them. They also ditched the valve stem shroud as again there was found to be no benefit in their retention.
So later heads did not have the circlips or shrouds.
The circlips were fitted as BMC expected the cotters to pop out at high revs which they never did. The shrouds were supposed to keep oil away from the valve guides but again they did not keep the oil away from the valve stems and guides. The only sure way to keep oil away from the valve stems (especially the inlets) is to fit the top hat seals with the correct grooved valve guides. The top hat seals should only be fitted to the inlet valve guides as the exhaust valve stems need all the lubrication they can get as unleaded fuel has little if any lubrication qualities. On the induction stroke oil can be drawn down the inlet valve guides/valves by the depression created in the inlet tract if the top hat seals are not fitted. The little 'O' rings supplied to fit around the valve stem are next to useless and if fitted are a poor substitute for the top hat seals.