is there supposed to be a valve stem seal on each valve?

i have not disassembled the head i have just bought, but it looks as though there are only 4 stem seals fitted?

the invoice from the head builder says i have been charged for a quantity of only 4 stem seals.

either he has only charged me for 4 and fitted eight or am i seeing things?

may have to pull the head apart and double check? or just call him and ask if he fitted 4 or 8.

jason

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'66 BRG Morris Mini Deluxe 60HP ATW

Some only fit them to the Inlets, which is OK

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is there any advantage in this?

i bought a full gasket set aswell which has a set of stem seals in it. should i put the other 4 on the exhaust or not worry about it?

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'66 BRG Morris Mini Deluxe 60HP ATW

I fit them to every valve. By not fitting them on the Exhaust is being a tight-arse.

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Cooper S only got 4 valve seals on the inlets originally.
There is no real vacuum on the exhausts, and Vizard and others recommend no seals there on performance engines. Particularly if you run bronze guides or K-liners (which need lubrication).
850, 997, 998 & 1098 motors up until the mid 70s didn't get these seals. They got O-rings in the spring retainer, under the collets.

From mid 70s on, `99H' prefix (late 998) motors got 8 seals.

The ones that in the gasket sets are pretty worthless, after a year or two they go hard and useless.
Whether you fit 4 or 8 won't matter much.

I buy good Viton seals from USA, but I only fit 4.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

ok good to know. i did see some orings on some of them under the collet.

i trust the builder of the head that he has put it together correctly, as i am not experienced with these engines yet, but just wanted to ask the question as usually you have a valve stem seal on every valve.

ok so stem seals on just the inlet are ok? cool

thanks guys

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'66 BRG Morris Mini Deluxe 60HP ATW

There is a theory that a scavenging exhaust (just like the LCBs) can suck oil past the guides when the valves are closed at high revs.
I know that some very high performance engines engines have had problems with the guides carboning up and causing valves to stick open when they are not fitted with seals as well as the problem of high oil consumption.

But if this is a problem with the A-series I don't really know.

I gotta say I had some problem on my engine, it was using a little oil I couldn't account for at first. The guides were new with the rest of the engine and it wasn't getting past the rings as far as I could see. I put the seals on the exhaust valves and oil use is now zero from that moment on. It was with a set of LCBs if that is of any use...and as I said the guides were new..

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Is that what it was? I remember you mentioning the oil use, but never heard what was the cause. Interesting...

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Simon

The adventures of an owner builder in the Tallarook Ranges

Maybe the factory fitted 8 seals on later cars for emissions reasons.
Pity they didn't choose a decent material that stayed soft and working!

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.