mk1-forum.net

Two questions, really...

1) Later type, just use them on the inlets, or both the inlets and exhausts?
Road engines:
1330cc & 1480cc
Both have 1.468"/1.218" Rimflows. Manganese bronze guides.
643 & 276 cams, 1.5 Rockers...
14" Steering Wheel, NO DICE!

Mostly, I have only put on 4, but I thought I'd just ask here to find out what others
think about this...

2) Early type, a more general question. These 'o' ring type, are they really a seal,
or just there to take up the initial slack in the collet groove? It's been many years
since I had these, but I may be about to look at a Morris Minor which has this type.
How do they "seal"? ... or don't they?

OK, three questions...

3) Is it worth putting the late type seals on the early heads as well as the 'o' rings?

Ian

Personally speaking I have never seen the point of those stupid little rubber ring things. As you suggest, I have always been of the opinion that they were there to hold the valves in during assembly more than anything else.

As for the "S" type cup ones. I use these on inlets but don't bother with the exhausts. If however the guides are the early smooth type with no recess to accept the lip of the oil seal I doubt if they would fit or stay on. Whenever I get guides fitted I always use the 1300 type with the groove for the cup type oil seal.

the little o rings are designed to go in the collet groove on the early valves that use the 2A11 large keepers

I think they are more to stop the collets shuffling in the top caps / collets grooves than anything to do with stopping oil going down the guides.

some people just poke them onto the valve stems, but this doesn't really achieve anything.

the later top hat stem seals are a far better idea, fitted to the inlets only - the expensive brown vitron ones are great

Thanks, gents...

Pretty much what I had thought.

Just before I wrote, I'd ordered some of the "expensive" ones
from MiniSpares. I got 8, so I probably have 2 heads' worth!

I did have that problem once where I tried to put the later seals
on a head with groove-less guides. They got dragged off quite
quickly by the inner valve springs... Lesson learnt, the hard way!

The Minor had a supposed engine rebuild a few years ago, along
with again, a supposed conversion for unleaded. Until I get the
chance to have a proper look at it, I shall reserve judgement.

I might be lucky and find "groovy" guides. I am a bit dubious of
what I might find as post "rebuild" it still sported its original totally
knackered rocker shaft assembly. This was at a time when you
could still go down to a breakers yard and pick up a good/better
used one off virtually any 'A' Series engined car...

Ian

Ian,

I am currently 'refreshing' a head for my 1275, was running with just the 'top hat' seals on inlets but was getting a bit smoky and I suspect there is oil getting down the exhaust guides when engine is hot. Quite a bit of muck and soot at lower end of exhaust guide... and there does not seem to be excessive wear or clearance between stem and guide.

I will be putting the 'worn' top-hat inlet seals on the exhaust guides and fit new top-hat seals to the inlets, and see what effect this has.

mk1 wrote:As for the "S" type cup ones. I use these on inlets but don't bother with the exhausts. If however the guides are the early smooth type with no recess to accept the lip of the oil seal I doubt if they would fit or stay on.

I recently had a bad experience where a very well known A-series specialist fitted the cup-type seals to guides that were not machined to retain them properly. They worked well at first, until they came off the guide, and started riding up an down on the valve stem. The then started working like little oil pumps, forcing copious amount of oil down the guides....probably more than would have been te case with no seals at all.

When I was first troubleshooting this, I mentioned that there were no seals on the exhaust guides, and this resulted in a lot of grumbling on this site. I have spoken to many engine builders who don't bother with seals on the exhaust, so I wasn't wiling to accept that the "missing" exhaust seals were the root cause....especially when it didn't smoke at first. After resolving the seals on the inlet guides, there is no longer any hint of smoke, even without the exhaust seals.

I've always used the cup type on all 8 valves. The Pinion 8 port head keeps alot of oil up top, which is why I do this. In fact I have recently put a drain on it.

I am in the process of building a couple of 850s for early UK Mokes and a 997 Cooper. Most on my work since the early 70s has been with 1275 based units. Funny to run into the wide keeper valves. It sounds like some here like myself before I went to work for 25 years in an auto machine shop don't understand the o ring seal. The correct assembly is to place valve in guide, fit spring and retainer in place and compress, force the o ring into the wide groove on valve above retainer. Then place the valve cotters above the o ring and release spring compressor. This way the o ring seals the valve stem to the retainer forming a very large umbrella seal of the whole assembly. All small block Chevy engines used this and only this until the new generation engines appeared. That was longer than the mini was in production. Steve (CTR)

CooperTune wrote:This way the o ring seals the valve stem to the retainer
forming a very large umbrella seal of the whole assembly.

I'd never thought of it this way! Great logic...

It does assume, however that the oil would be dripping vertically
downwards from somewhere above the top of the valve for it to
be of maximum benefit. I am not convinced that this would always
be the case. Hence, possibly the later idea to halt the oil
movement much lower down on the stem, immediately above the
top of the guide.

Ian

I run 8 standard ones

But MRA use to do some good ones but depends if anyone new the brand I didn't unfortally