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Hi Everybody,
Just in the process of fitting some aftermarket valve springs to a Holden 304, but the oil shield at the top of the spring does not fit. Not sure how this will go if I just use the standard valve guide seals without the shield in place.
So does anyone know if there is an umbrella type oil seal that is a direct fit to these engines without machining the guides? Something easily available? I have heard that umbrella seals from some Fords will fit but no idea what model.

Thanks

Generally you can get away with losing the oil shield and just running a retainer only.

No alternative stem seals that I know of without machining the guide - you can buy a simple tool which locates in the valve guide to cut them down though.

I have just found the Comp Cams CO 502-16 which is the umbrella style. They should fit given the dimensions, but can't be certain. Using the factory seals with no shield can't be any worse than the seals I pulled out.

if your referring to the metal bit that goes between the spring and the retainer and covers the first few coils of the spring then yeah its pretty common to run without them.

Yep that's the shield I am referring to. Do they go OK on daily drivers though? Don't foul plugs or use oil?

that's a good question, I'm not really sure .... most of the ones I've done it for a race cars so its hard to say....

I know one mates 304 never had them and I don't recall it particularly using oil or anything like that .... it was a daily, but it wasn't real practical due his choice of cam and converter

ive run no stem seals on exhaust valves before, small bit of smoke on start up and thats it

Macca97 wrote:ive run no stem seals on exhaust valves before, small bit of smoke on start up and thats it

So say that is better on the exhaust as it reduced valve guide wear.

I wouldn't run without the seals, you'll find a lot of crap on top of the piston in short order. It will be fine without the shields, running it more regularly is probably better than less. Mine hasn't had them for years and there's no issue, still has standard seals for now.

The bucket style seals will get close to fitting on some heads, depends on the casting. You don't really want them popping off though, the machining simply removes the rough casting and makes the outside of the guide circular/centred so they sit properly. If you're not going to the extent of machining for double springs at the same time you could probably do this with a flexi adapter using a hand drill. If you don't machine the guides then just stick with the standard o-ring style seals, they will be OK (just be careful not to destroy them on installation).

Thanks for the replies.
I ordered a set of umbrella seals lunchtime yesterday just to see how and if they fit. If not, will just run with the o’rings on the stem.

Some of the industrial engines get away with no seals on the stems at all, but on others the stems seals are critical. I have seen one engine which set fire to the carby from stem seals installed incorrectly – plug fouled and back fired into the manifold. Too much oil down a hot valve stem can also form a varnish that can stick valves open. None of this should be an issue on automotive engines though.