I had the head on my 1968 4.2 L engine rebuilt. Now with the cams disconnected from the timing chain sprockets, I find the resistance to turning the can shaft with long handled pliers is great - I can hardly rotate it except a few degrees.
Is this normal? I have no experience with this and didn’t try the same thing before the head was rebuilt.
Did the shop do something wrong, such as tightening too much on can brackets?
It is difficult to rotate the cams because of the effect of the tappets. However, you may also wish to Plastigauge the bearings to make sure the clearance is coorect
To reiterate an earlier warning I hope you aren’t rotating it more than a few degrees, it it will collide with the other cam (unless the other cam bearings are removed.)
Assuming you’re just trying to move it a bit to get the TDC tool on, then the right tool is vice grips. I wrap a shop towel over it, and then clamp down. It rotates easy enough once started.
Phil,
Is the head off the car??
If the head is on stop trying to turn the cams independently as you could be striking a piston top.
Assuming the head is off the car and you can see if valves are about to touch you will still need at least enough force to overcome the springs. I would have not thought it would be easy.
Matt
Tell us if the head is off the block. Mine will turn great when fitted and torqued to the block, when sitting on the bench, not so easy. As said, do not attempt to turn the cams without the chain fitted properly.
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Phillip,
Do you realize that the valves extend below the level of the head when fully open and can hit the pistons if the camshafts are rotated when they are not properly connected and timed with the rest of the engine?
I suspect that you may have bent some valves by rotating the camshafts while they were disconnected from the rest of the timing gear and some of the valves hit their pistons.
The way to check for this is to set the engine at Top Dead Center, connect the camshafts to the sprockets using the timing tool, and then check your valve clearances.
Paul
One cam installed, no valves, you can turn the camshaft by hand. At least you should be able to.
One cam installed, valves installed, you cannot overcome the valve springs by hand. That is normal, and so are the few degrees that you can turn them by.
The valves cannot only collide with the pistons and each other, they can also collide with a tabletop so you need to put something under the head as to give them room to extend below the face of the head. Particularly the intake valves are at risk.
A few degrees are okay but never more. If the engine is put together completely it is easier to turn as a whole, possibly because everything cancels out reasonably well.
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From his previous posts, I’d say the head IS installed and torqued so moving the cams more than to set them correctly (a few degrees) is NOT a plan.
Camshaft bearing caps may have been installed in the wrong locating , the stamping on cap and head should be checked , starting at 1 thru 8.
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