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Chris H
Forum Moderator
Joined: 02 Mar 2004
Posts: 19978
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| Posted:
Fri Jul 22, 2005 1:15 am |
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I wasn;t sure where to stick this but here will do I suppose.
Docherty sent me a head for headwork a coupel of weeks back, due to me being busy its only 2 nights ago I looked at it and popped the cam carriers off.
I had a quick glance before the the teppet bores were in decent nich and the ports and chambers again in good condition with 100% seal! Which is rare tbh.
anyway cam carriers popped off, look at the cam bearing journals
a close up
on the head itself, not oil feed hole and lines emmiting from it
anoher head shot
The rest of the head is in good nick, there seems to be no oil issues in the tappet bores only the cam bearing journals.
So either oil changes have been neglected or maybe a pocket of sand from casting had opened and sent sand around the engine.
I don't know.
The head could still be used but like Doc said another head is cheap and its foolish to use it especially when ghes gettign cams and I would never be fully happy with it myself. |
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Neal
Forum Moderator
Joined: 18 Feb 2004
Posts: 7432
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| Posted:
Fri Jul 22, 2005 1:18 am |
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They look nice dont they!  |
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Chris H
Forum Moderator
Joined: 02 Mar 2004
Posts: 19978
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| Posted:
Fri Jul 22, 2005 1:21 am |
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yeah.
I was saying I could clean them up a bit and iot could be used but I would never be 100% happy with it.
You can catch your nail easily on them. Its like 120 grit sand paper really.
The 2nd pics the best, if you look you see the plain nice line about 2mm wide, thats where the channel in the cam is so theres been no wear there. If you look to the left of it ypou can see how much the bearing face has worn down! |
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Doc
Site Subscriber
Joined: 11 Feb 2005
Posts: 2929
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| Posted:
Fri Jul 22, 2005 1:36 am |
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first time i've had a chance to look at it.
Thats definatly not too clever!
Ah well, I'll soon have a new one with Chris.
I'll put some bit's on that one and use it as a spare or something? |
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Chris H
Forum Moderator
Joined: 02 Mar 2004
Posts: 19978
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| Posted:
Fri Jul 22, 2005 1:37 am |
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yeah you can do.
I won't bother cleaning it! |
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Neal
Forum Moderator
Joined: 18 Feb 2004
Posts: 7432
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| Posted:
Fri Jul 22, 2005 1:40 am |
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how come they dont use bearing shells on the cams like the crank and rods anyway? |
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Chris H
Forum Moderator
Joined: 02 Mar 2004
Posts: 19978
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| Posted:
Fri Jul 22, 2005 1:45 am |
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aluminium is a good bearing material thus no need.
OHV engines with the cam in the block use bearings.
But OHC/DOHC cams run directly in the heads if they are aluminium.
If the oil changes are kept up and assuming theres no problems with trapped sand no longer being trapped there shouldn't be any wear.
As you know a plain bearing operates on the floating principle so there should be no contact. If there is its either on 1st start up after a long sit or a 3rd party beign involved, like grit.
Itsd a pain in the arse in situations like these though! |
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