Stem seals

[murray33]

Hi everyone, anyone know the correct type of valve stem seals for a 61 948 and where I can get them? The first type i bought were so tight i split a couple putting them on and the next type were quite loose so after a couple of hours running they've split! Can I get away with using the nearly new head gasket?
Thanks very much

[rayofleamington]

Can I get away with using the nearly new head gasket?

It's a risk.

where I can get them?

Moggy specialist will probably be fine if it is a completely standard head and if all those heads have the same seals, but if it's anything out of the ordinary, then you'll be back to square one.

I would try an engine reconditioning place - maybe one that specialises in A-series, and give them enough dimensions (and head part number) so that they can find the right seals. Engine recon places should be able to put you on to the right part (or the right supplier?) which is likely to be at least as cheap (cheaper?) than going through a spares agent. This principle can be used a few ways, for example bearings can be cheaper from bearings suppliers etc.. but you have to know which places to contact and what exactly to ask for.

[bmcecosse]

The old O ring type seals are a complete waste of time - useless. Better to fit newer type valve guides which have a wee external groove near the top and then fit the proper top hat seals - to the inlet valves only ! Your valve guides are bound to be worn anyway - new ones are very inexpensive and easy to fit. You could just chance the new type seals on old guides - they may be ok. Worst that will happen is a puff of smoke on the over-run. Hardly worth worrying about. New gaskets are only £3 or 4 - not worth chancing it. Why did it have to be disturbed ??

[murray33]

I took the head off to change the stem seals as I havn't got a compressor at home to keep the valves from opening. Could I combine the o ring type with the newer type?

[bmcecosse]

Not really ! Just use the new top hat ones - they seem to have a wee spring round them now - which will probably hold them ok. Just the inlets mind - not the exhausts - they need some lubrication !

[doobry]

Just the inlets mind - not the exhausts - they need some lubrication !

The inlet valve stem has a relative pressure caused by the inlet vacuum - this has a tendency to draw oil through the valve guide clearance, hence needing to be sealed.
The exhaust valve is subject to high pressure from the exhaust gasses therefore the opposite effect occurs, therefore (unlike some more modern engines) the exhaust valve stems dont get seals.

[Cam]

What's everyone's opinion on the quality of the seals nowadays? How long should they last before becoming ineffective? It's annoying to have a puff of blue smoke on start-up but it's not really worth it to take the head off and remove the springs. It does not detract from the performance of the engine and it's not hurting anything it's just really annoying!

[Kevin]

Cam I know how frustrating it can be I assume with your tuned engine that the later type are fitted like these ones.
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... eName=WDVW
Also they are a specialist and are reccomending fitting a full set of eight, I wonder which is best ?

[bmcecosse]

Keep the exhausts lubricated - no seals.

[murray33]

So should the seals actually push over the guide or just rest on top? I have fitted new guides but they have no groove (couldn't get any with grooves).

[bmcecosse]

They should push over - if they have the wee springs round the edge they should hold on ok.