2011 1.2 12v Polo camshafts

[123-yoyoman]

Hi
The timing chain slipped on my daughters car on start up. Fortunately the damage was limited to six bent inlet valves. I have replaced both inlet/exhaust valves and had a machine shop replace the valve guides. I am now reassembling the top end of the engine. I have refitted the cylinder head and the rocker/camshaft cover.
I have bolted the pulleys onto the camshafts ready to fit the timing locking pins. As per the Haynes manual, I have ensured none of the pistons are at the top of their travel.
However I am confused as to why the camshafts do not turn smoothly. When using a socket/bar on either of the camshaft pulley bolts the camshaft will need some force before it will turn. Then it will 'ping' free and require more force until it will turn again. I would guess the resistance each time corresponds to a camshaft lobe opening its valve but is this normal. I re-examined the camshafts in their housings and they both move freely and smoothly prior to fitting to the cylinder head.
Should there be so much resistance to the camshafts turning. Surely they should rotate more smoothly.
I am unfamiliar with these engines so any advice would be very welcome.
Many thanks
Pete

[RUM4MO]

I'd think that what you are describing is normal, do you not remember what the profile/shape of the cam lobs look like, ie they are circular for quite a lot of their "time" then rise quickly to a short peak then fall away quickly - so you will be "feeling" this as a change in effort required to rotate each of these cam shafts.