Hello all.
I have a vrs for my head but instead of valve stem seals i have removed the kit has O rings. Do these do as good a job and do they just slide over the valve stem ? Thanks.
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| Author: | mmiller6512 [ Wed Apr 07, 2010 11:46 am ] |
| Post subject: | Valve stem seals |
Hello all. I have a vrs for my head but instead of valve stem seals i have removed the kit has O rings. Do these do as good a job and do they just slide over the valve stem ? Thanks.
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| Author: | simon k [ Wed Apr 07, 2010 11:50 am ] |
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If you removed seals, then you should be putting seals back on, unless they weren't meant to be there in the first place. The VRS kit should have come with seals... what sort of head is it? |
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| Author: | mmiller6512 [ Wed Apr 07, 2010 11:54 am ] |
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late 998cc from a moke. |
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| Author: | simon k [ Wed Apr 07, 2010 12:06 pm ] |
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this small bore kit has seals... 
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| Author: | mmiller6512 [ Wed Apr 07, 2010 12:19 pm ] |
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I also have a 12G202 head . What seals should it have ? Thanks. |
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| Author: | drmini in aust [ Wed Apr 07, 2010 1:15 pm ] |
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It depends which valves are in the head, regardless of which smallbore head it is. eg there are 2 different 202 heads, early and late. If the valves have a single 1/2 round collet groove (~1974>), they take the cup seals on the guides. If they have a wide square collet groove (>~1974), they take the O-rings, which sit in the collet groove before the collets are put in. But all 1275 heads take the cup seals. `Metro' cup seals which are commonly supplied in kits now have a spring on the lip, and are allegedly better. But they all go hard in a year or two. I buy Viton seals in from USA. There is also a Nissan 1400 seal that fits. Both these don't go hard. pic of the Nissan one- (used by guys on the Sth Africa forum) My USA ones look the same but the top is blue. 
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| Author: | graham in aus [ Wed Apr 07, 2010 3:28 pm ] |
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Hi Kev! 
I've always wondered about those O-ring types, can you see a point to them, how do they do anything? Sorry if i'm being a bit dumb, but dont they just sit up top of the valve stem? how can they prevent oil going down the guide? Do they have another function to do with the collet? Just interested in your thoughts 
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| Author: | drmini in aust [ Wed Apr 07, 2010 3:46 pm ] |
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Graham, I think the O-ring used on the old wide collet valves serves 2 functions: 1. It stops oil getting through the collets then running down the valve stem, 2. It keeps the collets tighter in the groove. Those old style valves used to have a spring clip around the collets too, but we found back in the 60s that if you revved a Cooper hard they all fell off and sat on top of the head.
These days if doing up an old smallbore head I fit the cup seals on the guides, with a bit of Loctite 262 inside to hold them. You need to check the valve caps clear the seals at full lift. I put Loctite in my metal yankee seals too. |
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| Author: | graham in aus [ Wed Apr 07, 2010 4:18 pm ] |
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Thanks Kev, that makes sense, I've just put that type of head together, I added Cup seals as well as the O rings, I did think about some loctite on them as well, cause it was a 295 head, and the inner spring got close to the cup seal as it spreads a bit without the semicircular slot to click into. I may well take them off again and dab on some loctite! I only put the cups on the inlets. Cheers! 
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| Author: | mmiller6512 [ Wed Apr 07, 2010 5:15 pm ] |
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Thanks everyone it all semms a lot clearer now. |
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| Author: | drmini in aust [ Wed Apr 07, 2010 7:01 pm ] |
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graham in aus wrote: Thanks Kev, that makes sense, I've just put that type of head together, I added Cup seals as well as the O rings, I did think about some loctite on them as well, cause it was a 295 head, and the inner spring got close to the cup seal as it spreads a bit without the semicircular slot to click into.
I may well take them off again and dab on some loctite! I only put the cups on the inlets. Cheers! You really only need cup seals on the inlets. Cooper S never had them on exhausts, nor did Fiat, Alfa, and a bunch of other performance cars. Vizard suggests leaving them off the exhausts, as the valve stems need some lube & there is no vacuum there anyway. |
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| Author: | Asphalt [ Wed Apr 07, 2010 7:19 pm ] |
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Interesting - I'm going to try some VW stem seals; they look very similar to the Nissan ones
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| Author: | drmini in aust [ Wed Apr 07, 2010 7:24 pm ] |
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The Nissan ones are for 7.0mm valve stems, this is so close to the 9/32" Mini stem size it ain't funny. They are 12.0mm dia inside the metal case, which fits Mini guides. |
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| Author: | Asphalt [ Wed Apr 07, 2010 11:05 pm ] |
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drmini in aust wrote: The Nissan ones are for 7.0mm valve stems, this is so close to the 9/32" Mini stem size it ain't funny.
They are 12.0mm dia inside the metal case, which fits Mini guides. Same dimensions as the VW ones But they'r a bit cheaper over here
I realy hope they last longer than the Rover ones... |
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| Author: | drmini in aust [ Thu Apr 08, 2010 8:29 am ] |
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Mine were still soft and working after 30,000 miles last time the head was off. They are still on the head after another 10,000M. |
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