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I’m rebuilding my head and have scrupulously torqued the camshaft caps to the specified 16lb/ft.

The cams seem very tight. I can turn them only with great difficulty, using snap ring pliers in the camshaft sprocket holes.

I have visions of destroying the cam bearing surfaces in the first 30 seconds after startup. I’ve used lots of assembly lube. Need I worry?
 

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The cam caps were machined in place then marked for position. (or perhaps marked then machined but the point is they have to be returned to their correct, original positions.

Exhaust side cam caps are numbered 1, 2, 3 front to rear.
Intakes are numbered 6, 5, 4 front to rear.
 

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Did you try them with the valves out? If, how did they turn? Even with the valves in, you should be able to turn the cam pretty easily with a cam turning tool to check clearances. Sounds like something's not right. Bent cam, bent head, caps in wrong places.
Andrew
 

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Sounds like something's not right. Bent cam, bent head, caps in wrong places.
Andrew
I agree with Andrew but suspect the wrong cam turning tool is the problem. "using snap ring pliers in the camshaft sprocket holes"

There will be some resistance while turning the cams due to the valve springs. Also make sure the valves are not hitting anything, like your work bench.

Mark
 

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I agree with Andrew but suspect the wrong cam turning tool is the problem. "using snap ring pliers in the camshaft sprocket holes"
While I agree that snap ring pliers aren't the optimal tool to use, I'm not getting why using them would change the torque. Heck, a lot of hack mechanics use vise grips for this purpose (which I do NOT recommend). Seems that there was a BB thread some time back discussing a commonly-available tool that approximated the Alfa factory cam turning tool.

The big question that Canadian Spider has left unanswered is whether his cams were trial fit into an empty head, or whether he is turning them with the valves & springs in place. With the valves & springs it does take a bit of torque to turn each cam.
 

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Richard Jemison
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Cams

Well, "very tight and with great difficulty" are nebulous descriptives.

There are several factors that change the turning effort.

Cam cap (bearing ) clearances. The specified clearances for cam to cap clearance is .0008"-.0015". at .0015 that is loose. You must measure with plastigage under the cam, not above due to springs holding the cam off of the bottom surface..

On the tighter side it does take effort to turn, In a empty head (no valves springs and followers etc) the cam should not spin easily by hand. You should be able to turn it though without much effort.
(Be aware that too much clearance is the primary cause of low oil pressure at idle.)

With factory cams turning them with channel lock pliers on the sprocket should be doable with little pressure, if the cam jumps ahead as a lobe is closing that is normal when clearance is not in the small range of clearance. There the effort to turn is reduced greatly, but no rapid turn on it`s own.

With modern fast ramp rate cams there is more "load" needed so open the valves and more pressure to self close. In a engine with chains attached the opening and closing effort/self closing force negate each other to a large degree.

Do you have the caps in the correct position. They are numbered but they also have to be oriented at that position as well. Look at the front caps with the timing marks. If those two are in the correct position the #1 cap is on the exhaust side. The Numbers are on the outside of the cap and 2 # 3 should have numbers on the same side. Intake is # 6 and #s are on the outside and same for 4 & 5.

If that is correct, and it`s still "overly hard to turn", loosen one cap at a time to see if it changes force needed. If not tighten that one and go to another until you find the offending cap.

If that doesn`t result in correction remove the cams & cam followers and using a straight edge on the center of the bottom of the bearings see if they are straight/flat. If it "rocks or does not tuch one of the bearing surfaces you have a warped head. These can be corrected by line boring the bearings & caps.
I have to do that frequently and had a tool built for that purpose.
 
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