Cam run in proceedure v8 thor

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Willos

Active Member
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Huntingdon Cambs
Just about there with my new cam rebuild with loads of other new gear thrown in to make sure it's a kitten purr. Cam lobes covered in cam grease. Lifters soaked for three days.
What's the official run in proceedure on first start up. It's difficult to keep the coolant topped up whilst keeping constant revs
 
There's no camshaft running in, just make sure you top up the engine to the correct level, I presume you have covered the camshaft/camshaft followers with good quality rebuild engine oil/grease. Start the engine just don't rev it until the hydraulic followers have filled up and taken out the valve train slap..
 
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martynv8 said:
Thought you had to run a cam in @ 2000 rpm for 20 mins or so?
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Would you rev a completely fully rebuilt engine at 2000 rpm for 20 mins?

I prefer to break an engine in gently, but if I had only replaced the cam/followers. I'd wait until the lifters have taken up the slack then drive as normal for a while before caning it.

Never heard of a camshaft having to be run in.
 
From first principles, limited bits that I know.
You are principally trying to avoid galling. It used to be that high zinc phosphate greases were used for this, or molybdenum disulphide. Maybe something better exists these days.
Also, camshafts used to be Parkerised (see Parco-Lubrite for example) - this is a black or grey oil-retaining coating - again, there may be something better these days.
Whichever way, you need to make damn certain that it's all well lubricated - the first few minutes is going to be crucial.
 
sassanach said:
yup, bearings are pressure fed, lobes are splash/oil mist from internal engine activity.
Click to expand...

Nothing to do with over spill from pressure fed tappets or the pressure fed oil being thrown from the crankshaft as it rotates then?
 
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Thanks. I think i'm going to chuck in some extra lube in with the oil so not to take chances. Already has Joe Gibbs building grease on all thing rubbing .
Good article from Castor on V8 builds Just goes to show even the top builders get it wrong now and again. My last cam had 2 rounded lobes so keeping fingers crossed or its Bay of Pigs for her (spares or repairs of course). 11 years I've had her so purrrrrr or else
 
>>Joe Gibbs Assembly Grease

I'd not heard of this, but reading up it sounds just like the stuff we used years ago. Sticky, glutinous stuff.

>>>purrrrr or else

Yeah, purr dammit.


Good luck.
 
Just don't let it idle - cam wear is highest at idle - cams are lubricated by building up a hydroscopic wedge of oil between the lobe and follower due to the relative difference in speed between the parts. once the cam rotates as far as the nose of the lobe, that wedge breaks down and spills away, at lower engine speeds the wedge has more time to spill away exposing the lobe to metal on metal contact. 2,000 rpm for as long as you can bare it is the best best. And don't idle it unnecessarily for a while after.
 
StuckAgainSteve said:
Just don't let it idle - wedge of oil between the lobe and follower - 2,000 rpm for as long as you can - don't idle it unnecessarily
Click to expand...


This sounds very wise and totally correct, but is counter-intuitive. I'd have run it slowly and "gently" which is clearly wrong. Good insight, thanks.
 
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