Morris Minor Owners Club

Just finished rebuilding the head on my new engine. I have top hat type seals with little springs over the guides, and also small O rings under the cotters. The question is - some of the o rings have got slightly caught on the sprng caps and don't sit true, being caut on the valve stem. Are they really needed if top hats in place? Do I need to remove the springs and try again?

Thanks,

Tom

You should use one or the other not both together.
If you use the TOP HAT seals you should really use the later valve guides which have a retaining grove for the seal. You may have to shorten those valve guides to suit your head.

Great, that is what I wanted to hear. Confusingly the head had both when I took it apart.

I think i'll remove the o rings. Athoug, is there any harm in using both?

The valve guides have the groove so all fine there.

Tom

There is a difference in the valve collet/spring cap/recess on later valves and your cylinder head arrangement may not be suitable for fitting the small 'O' ring. As your valve guides have the correct seal/location grove for the guide I would ditch the 'O' rings and just fit the TOP HAT seals.
There is a difference of opinion as to whether it is wise to fit TOP HAT seals to both inlet and exhaust valve guides. All the later BMC/BL heads that I have worked on have been fitted with TOP HAT seals on both inlet and exhaust valve guides and I always do the same. No doubt someone will advise otherwise!

Certainly DO NOT use both O rings and top hats. For Comp use the top hats are never fitted to the exhaust guides - to ensure adequate lube for the hot exhaust valve. I dare say it doesn't matter for road use - although I never fit them to the exhausts.

Strange, as both were fitted when I removed it, but Will go with just the top hats.

Thanks as always,

Tom