Yeh g'day. I'm looking for a set of seals for my YT head on 202. Last few times the manifold has been off I noticed what I thought was fuel residue in the ports. After having a think, and noticing the blue puff on startup, I figured it was oil... leaking down the almost new guides... the valve stems still have machining marks on them. The stems are 11/32 or .344", and the guide boss is 14.8mm or .5827" . I measured the old YT head but it seems different to the new YT head... the seals I bought from Summit are too big! Bugger! Anyone have any ideas? Googlising doesn't help any.
Umbrella valve stem seals.
Started by
Dave6179
, Dec 30 2014 04:04 PM
8 replies to this topic
#1
Dave6179
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Posted 30 December 2014 - 04:04 PM
#2
EunUCh
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Posted 30 December 2014 - 05:30 PM
#3
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Posted 30 December 2014 - 05:38 PM
... the valve stems still have machining marks on them.
WTF???
Care to elaborate why the valve stems are not smooth?
#4
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Posted 30 December 2014 - 05:46 PM
Was thinking the same thing?..they should be smooth (polished almost),the guide is is usually honed for clearance...and no machine marks visible.
Some of the early V8's actually had "rifling" grooves in the guides...oil pumps?
Let's hope they have not gone back to that mentality with the six?
#5
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Posted 30 December 2014 - 06:26 PM
They hang on,but need a "special tool' to fit them.
http://www.ebay.com....lpid=107&chn=ps
To fit these don't you have to machine the valve guide casting boss?
#6
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Posted 30 December 2014 - 06:49 PM
Yes,the boss needs to be cut back from it's ugly standard cast shape,there is cutter available for this and the 50 odd thou difference in ID of seal and boss equates to a good fit,they do stretch quite a bit.
#7
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Posted 31 December 2014 - 11:20 AM
All the heads I reco'ed I never machined the valve stems, valve faces and tips but never the stems, if the stems are worn it is time for new valves.
#8
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Posted 31 December 2014 - 02:12 PM
WTF???
Care to elaborate why the valve stems are not smooth?
Can't tell ya why not. They have what I would liken them to as ribs similar to the ARP waveloc bolts I used. Hardly noticable to the touch but visible. The old head... which I had on for over ten years, looks identical, 173 with the chambers machined out, and of course, with the miles on it the stems are smooth, and move sideways! It did have seals on it but don't think they were correct for it as they must have been fouling on something and came apart.
#9
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Posted 31 December 2014 - 02:14 PM
To fit these don't you have to machine the valve guide casting boss?
The YT heads I have have the boss diameter deduced to fit the small inner coil spring. Obviously the one I measured before I bought the seals are a different size to the head they were to go on. Dammit!
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