oldmansteptoe
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| posted on 3/2/14 at 11:03 PM |
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damaged 234 cam
Hi, im about to build a nice fast road 1700 xflow and have a choice of cams to use. I have a nice bcf3 and kent 244. I also have a 234 but has slight
damage to one of the journals, does this now make it scrap, or can it still be used? Is damage to a journal as bad as damage to a cam lobe? What do
you fellas think?
Thanks
Not sure how i can post a picture on here!??
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Nickp
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| posted on 4/2/14 at 07:13 AM |
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Depends how bad the damage is TBH. It's probably not as bad as a damaged lobe and easier to repair if you chose that I reckon.
To post pics here you need to host them somewhere then cut & paste the IMG link into your post. This is how I do it, from photobucket in my case.
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Paul Turner
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| posted on 4/2/14 at 11:45 AM |
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The damage may not be bad but it could still damage the bearing that is pressed into the block.
Damage never gets better, it has a habit of getting worse.
The cost of a strip to simply replace the cam bearing will be more than a new cam costs.
If it all goes bad it could destroy your engine.
Is it worth it when you have 2 other cams, having used both the 234 and 244 I know there is not a huge difference between them in a light car, even a
254 drives OK in a Seven.
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SteveWalker
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| posted on 4/2/14 at 10:08 PM |
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What exactly is the damage like?
I once saw the crankshaft of a 30 year old, 150 litre, straight 8, gas engine that had an inch wide pit in it. The Engineer's advice was that if
it had no protruding edges or scores to scratch the bearing shells, then it would be fine!
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oldmansteptoe
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| posted on 5/2/14 at 07:48 PM |
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Thanks for the replies fellas. Hopefully there's a piccy now below to show the damage.
[img] [/img]
[Edited on 5/2/14 by oldmansteptoe]
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Nickp
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| posted on 5/2/14 at 08:08 PM |
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Bit blurry but that looks sh@gged to me.
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SteveWalker
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| posted on 5/2/14 at 10:58 PM |
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That looks almost like a flat across one area - how the hell could it wear like that?
If you were to use it, I'd expect it'd not be bad, as there is nothing to tear at the bearing, but the decreased area would increase the
wear rate on the rest of the bearing significantly.
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mark chandler
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| posted on 5/2/14 at 11:20 PM |
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I'd be worried if the oil feed for the journal exits over the shaved part as you will be dropping pressure, cams are not that expensive probably
better to bin it and use your more aggressive one or replace.
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oldmansteptoe
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| posted on 5/2/14 at 11:25 PM |
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yeah, shame but i might have to forget this one. im tempted to go with the bcf3 as ive done a dummy build with that and it wont need cut outs of the
pistons. the 244 i know will, but is there a set amount that would have to come off or would i need to dummy build again and measure the thickness of
the plasticine again?
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Nickp
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| posted on 6/2/14 at 05:58 AM |
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Even if someone told you how much to take out of the cut outs for the more aggressive cam you still need to do a dummy/dry build to measure the V-P
clearances.
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Paul Turner
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| posted on 6/2/14 at 01:30 PM |
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Looking at that photo it does not look like damage. It looks like damage may have occurred and the journal has been machined to remove it leaving
enough of the journal to run in the bearing. In truth cam bearings are not under much stress. The cam runs at 1/2 engine speed and the rotational
stresses are not that high. Its difficult to tell without seeing the cam but it may well be fine.
With regards to piston cut outs I always had mine machined to 6mm deep. That way they were deep enough for any cam I may have fancied fitting.
Don't forget that if bigger valves have been fitted it may be necessary to enlarge the diameter of the cutouts as well. After machining the
cutouts the compression ratio will be slightly lower. To get it back on a x-flow you need to deck the block slightly or fit a slightly thinner head
gasket. Only way to know for sure is to check the volumes before and after.
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oldmansteptoe
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| posted on 6/2/14 at 05:20 PM |
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You might be right there Paul. Thinking about it, it does look more like its been machined rather than actual damage. It was in a engine i was
informed was running alright and there was no other damage anywhere in the engine. Maybe it would be alright??
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