Camshaft fitting problem

[Shyster]

Hello all, I am currently refurbishing my heads, new guides, valves,springs, cam buckets and new camshafts. The problem I have is that as I torque down no.1 camshaft bearing the cam gets really stiff and difficult to turn. I have put the old cam back in and I still get the same problem. The cam turns ok at 10ft/lbs anything more than that it gets tight and at 14ft/lbs almost impossible to turn.
I thought that maybe I had mixed the caps from left and right heads, but I haven't as the cap from the other head doen't fit.
any suggestions
thanks

[european voyager]

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Is the cam bent ?

[Thurlo Squire]

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Are you putting no1 bearing cap on last and then the cam locks up or is no 1 the first cap that you are fitting and the cam won't turn?

Nigel

[Shyster]

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I don't think the cam is bent, as it does it with the old cam as well. I am fitting all the caps together and torquing them down from rear to front. cam turns smoothly when caps 2 - 4 are tightened, only goes stiff as I torque down cap 1.

[Kevin Garrod]

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Has the engine overheated? Could the head be warped?

[alan_thomas]

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Do I take it the head is off the block? if so do you know whether it was free to turn before you took the caps off. The point being if the head is warped but bolts down flat allowing the cam to freely turn i'm afraid the head may be scrap because skimming the head / block face flat will remove the warpbut will still leave the cam bearings out of line.

I did read once you can get them line bored and fit shell bearings thereby getting everything in line but cannot remember where I read it.

- Alan

[adieturner]

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Good engineering practise: Head should be torqued down to either the block or something known to be flat and then the camshaft bearings from centre outwards i.e. cap 3, 2, 4, 1 then 5.
If it doesn't turn freely then, as a loose assembly without valve spring pressures, you'll need to find someone who is happy to sleeve the caps/head together and line bore it with the head clamped flat.

[john 4d]

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I hada similar experience when refitting mine, hopefully you will find the same remedy.I refitted one of the cam caps the wrong way round, as the bore is slightly offset, this had the effect of clamping the cam shaft to the housing. If you've done this, reversing the cap isn't a quick fix, torquing down the cap will have distorted or flared it out, making it 1) difficult to remove and 2) a poor bearing fit around the cam shaft, again clamping the shaft but for a different reason, the flared cap is now flatted out slightly so it comes into contact with the shaft before seating on it's side faces. I reshaped mine by applyinga gentle squeeze across the cap between the jaws of a vice, checking the cap bore profile against the cam shaft journal, untilthe correct profile was achieved. I admit this was guess work, be carefulover doing it could over stressthe cap beyond re-use.After this, without valves and springs, I torqued the cam shaft in place to check free rotation, the result was a rotation as smooth and free as the sideI hadn't incorrectly reversed the cap.

[Sheepdip]

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Have you tried just fitting cap 1 to see if its cam or the bearing? Also is it really tight or just "tighter"? Have you checked for burrs on the cap?

I hada similar recent problem when I tried the cam without valves and it had tight spots. My engineer advised using cigarette powder(!) tolap thebearing, it was slightly better when he tried it he didn't have concerns as the difference in expansion rates means the cam would loosen off. We shall see.....