Eightbanger

Hi Guys,

Out of the 8 valves only 4 have O rings, the 4 with seals have a groove for the seal to sit in, but the other 4 stems haven't....is this correct or should there be seals on all of them?

cjsdad

The grooves in those valve stems are for the spring retainer locks, not for seals or o-rings. Valve stem seals will fit over the valve guide that sticks up in the middle of the spring pocket.

Eightbanger

In the first pic you can see that the stem on the left still has the O ring/seal attached, sitting just below the the spring retainer grove, the stem on the right in that first pic has only one groove which is only for the retainer but no second groove below it for the seal.

I have 4 valves each with two grooves and 4 valves with only one, the four with the two grooves all had a O ring/seals fitted (see first pic) and the others had none as they have no second groove for a seal.

So i'm confused as to why I have two different styles of valve stem....is it something to do with exhaust and intake?

cjsdad

That may actually look like an 0-ring in that groove, but it looks more like part of the valve stem seal has broken off and landed there. There is nothing to seal against where it is located, there would be oil on both sides of it on the valve stem. The umbrella type (brolly to you Brits) valve stem seals have an 0-ring like section that rides on the valve stem and if the seals have deteriorated enough that part would come off ending the sealing properties. This would cause excessive oil consumption and perhaps lots of tail pipe smoke. The exhaust valves get much hotter than the intakes and they would deteriorate faster so it could definitely be the reason for some valves having them and some not.

Rocketowner

Nigel ,there's an old post on the site called (Valve stem,umbrella seals) that explainsthe replacement Umbrella type seals. If you cannot find it let me know by P.M. Larry

Ozzie

I am assuming that you are talking about only one of the cylinder heads and not the entire engine. If there are no "umbrella" type seals, and the rubber stem seals are only on the intake valves, all is correct. The intake valve stems operate under a vacuum from the intake manifold and having oil travel down the stem is much more likely than on the exhaust valve stem which operates under a slight pressure. The small rubber piece sealed against the spring retainer which prevented oil from running down the stem and into the guide. Instead, the oil traveled across the retainer and down the spring to the cylinder head, missing the guide. Some of the older engines were constructed this way before the umbrellas were put into use.

Eightbanger

Sorry Larry didn't receive any email notifications that there were any further replies on this thread, only as you mentioned it on my thread about the skirts I came here...I will try and find it now.


Ozzie thanks, thats what I needed to hear, just nice to have your mind put at rest that all is as it should be.
Yes, just one head, so for now I can just renew the four square cut 'O' rings on each head or look into fitting umbrella type seals to all sixteen valve stems...where would I get them for a 303?
I'm still curious though as to why all sixteen valves in this Ebay listing come with the 'O' ring grooves and only eight out of my sixteen have provision for the 'O' ring.?
http://www.ebay.com/itm/1949-50-51-5...dU55EJ&vxp=mtr

Ozzie

After doing a bit of research, I found that it appears that a production change to the exhaust valve was made which affected the late production 1953 models which added the stem seal. (While less oil would go down the exhaust valve stem, some will go through.)(I have tried running without the exhaust valve seals. It burns more oil.) The 1949-early 1953 models did not have the seal on the exhaust valves. Also the part number for the 1954 exhaust valve is different from the late 1953, while the intake remained unchanged from 1949-54. Hence, if you wanted to utilize the "top hat" type of seals on the exhaust valves also, you could probably use the Wolverine aftermarket valves shown in the eBay ad. If you wanted to utilize the umbrella type seals, you would have to find some which accommodated the valves' stem diameters, the guide diameters, and would still fit inside the spring. This is probably possible, but I don't know a guaranteed fit source. The Olds parts book says that an umbrella type was available for the 1958 intake and exhaust valves. The O.D. of the umbrella is shown as 0.914 inch, group 0.308, part number 575142. Often the same umbrella can be used even with slightly different stem diameters as they stretch a bit.
Something like this may provide some ideas:

http://www.cometic.com/catalogs/sportcompact.pdf

cjsdad

So sorry Eightbanger, I never heard of such an oil control system. Glad someone else was able to help you out.

Eightbanger

Ozzie, we're lucky to have you....thank you for taking the time to research this...interesting reading.
So to keep things simple and as GM intended back then, I'm going to fit new 'O' ring seals and not stress to much about whether or not I should update everything, it's worked fine for 60+ yrs the way I found it, so if it ain't broke.

CJ, that's not a problem at all, you took the time to reply and that's appreciated, it's all a learning curve.

cjsdad

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Eightbanger

OK, here is another a pic of my valve stems with the two different types of seal provided in my Fel-Pro engine gasket set....
My question is, which one should I use? or is it just down to personal preference? baring in mind that it's only the four intake valves that have any second groove to install either type, sixteen of each type came in the kit.
Pic shows one exhaust valve and two intake valves with the different seals.

Ozzie

Often the kits contain "extra" parts so they can have more than one application. In this case personal preference may partially be the determinant. The kit has given you that prerogative. The newer engines often have the umbrellas on all valves, but that doesn't mean you have to. You can duplicate the original if you want. I wouldn't use the "O" ring on the exhaust if you put something there as there is no groove for it. If you used the aftermarket exhaust valve with the groove, it would be O.K. But without the groove, I'd use either the umbrella if you wanted "tighter" oil control, or nothing, as original. On the intakes, I'd use either the original or the umbrella (if it fits properly inside the spring). (But it would be lower on the stem, as the groove would be next to the retainer.) If you decide to use the umbrellas anywhere, be sure there is enough room for them inside the spring and between the retainer and the top of the guide when the valve opens. They are usually placed all the way down during assembly and then they get re-positioned on the stem when the valve operates for the first time. Use lubricant during assembly; it will help to keep the rubber from being "pinched", cut or distorted.

Eightbanger

Lost without you Sir. Thanks for your time again mate.