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MG MGB Technical - Valve oil seals

I've just bought new valve oil seals of the top hat type. Do they fit all the way over the valve guide or does the top part of the seal grip the valve? Advice would be appreciated.
Rod Merrall

Types with a metal band round them grip the guide so they don't go up and down with the valve. Without that it's probably a bit hit and miss.
paulh4

On my Peter Burgess Fast Road head he has only fitted seals on the inlet valves. Apparently with the bronze valve guides he makes and fits, the clearances are reduced and the seals are omitted on the exhaust to make sure some slight lubrication gets down the guides.
Mike Howlett

Thanks for the comments. I had't thought about the point you make Mike, my head was supplied and fitted by Oselli and only had seals on the inlet valves maybe for the same reason. Think I'll do the same.
Rod Merrall

Rod
I'd still fit the original 'O' ring type seal up under the keepers on the exhausts to stop oil getting down the guides after turnoff and getting cooked on the backs of the valves and stems-
Even though you're running hat type seals on the inlet, I'd be running the 'O' rings on the inlets as well--they don't do any harm being there as a backup
William Revit

To be honest we fit top hat oil seals on all valves on all road heads. Without seals on the ex guides there is a puff of smoke on start up. Some folk complained so we decided to fit seals on them all apart from race heads which have no seals at all.
Peter Burgess Tuning

With my own valves having 8mm stems and shallow spring caps I could fit neither type of seal (o-ring or top hat) so 45 deg tapered the top of the guide to leave the flat on top of the guide only 1/2mm wide. Needed special tool for installation so as not to damage it but has given good results.
Paul Walbran

This thread was discussed between 26/01/2022 and 30/01/2022

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