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Discussion Starter #1
So bit of a mini update (see what I did there? 馃ぃ ) I've recently taken possession of a JCW cylinder head with all valve gear still attached and is currently awaiting to go to the engineers for a p/test,skim,new valve guides as required,seats recut and a thorough clean. But on removing said valve gear I found that the cam is shagged! Cylinders 1 & 2 mainly, highly worn out lobes and lobe deterioration. Now the cam was always gonna be featured in B 1 N fodder as I've also taken possession of a spanky new PH2 (y) But I've seen posts like this before..... so did they just get the specs wrong at the casting stage or what?
Going off the few score marks in the cam journals If it were cylinders 3 & 4 you would say lack of oil pressure/ Infrequent oil changes+ high miles, iirc the head has done 125K and the score marks will come out with a light application of 2000 grit wet and dry (y) but cylinders 1 & 2 are at the oil feed end ??????
And what knock on effects does this have on the roller rockers? Am I gonna get premature wear of my new cam by using the old rockers? Do the rollers in the rockers stick? I know, by my own choice of replacement parts, I'm gonna get butt fucked by the man from Knights BMW, but if I order a new set of rockers I may get cavities invaded that really shouldn't be! :eek:
 

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Discussion Starter #3
Cheers mate, but bought the head to re build anyways. It just shocked me the amount of camshaft wear and lobe degredation on a modern ish engine that has roller rockers which are obviously designed to prevent this. Don't think I've seen a cam like this since the old pintos and Vauxhall OHC engines. 馃ぃ
Technically I've got two sets of rockers.... the ones that came with the head and the ones on my car at the moment, but the swap over has to be a weekend job, no more, as I'll be doing it at work, so there is a possibility of making a good set out of the pair.
 

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they might well be poor quality blanks who knows, maybe the factory thought a certain grade would do alright with roller tips, then maybe they're just affected by deteriorating oil pressure and/or maintenance, including cooling systems contributing to poor oil condition, exacerbated by typically ignored oil leaks and many cars running low on oil, as well as daft service intervals often exceeded. The rollers will either be marked or they won't, most get away with it I think, I have similar cams here, the worst had worn ends and mains plus a cracked inner pump gear. I think one roller only just had a mark forming in one spot and another around the circumference despite the disaster of a cam state. Still running quiet too, this you can see by the rocker arm colour wasn't a heavily varnished engine. Maybe the use of roller tips just allowed the use of a steeper lobe angle a swept follower would have struggled with. I think maintenance and related engine wear is the crux of it.
 

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Discussion Starter #5
That's it, its like poor casting quality and poorer heat treatment. While I'm waiting for the head to come back I can give the rocker units a good clean and inspection. We've got a parts bath at work which gets cleaned out regularly and very rarely gets used so the cleaning fluid is nice and clean. Then I'll just check for roughness in the roller bearings and inspect the contact faces. (y)
 
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