Cam Housing Refitting Problems

[Gray14]

I’ve taken the cylinder head off for an overhaul and with that off the car I’m fitting the camshaft housings to check the valve clearances.

When I refit the cam housing onto the cylinder head it’s impossible to turn the camshaft.

The cam followers are oiled and slide in the camshaft housing prior to bolting down, the valve stems in the guides also oiled.

I’ve tried fitting it with the cams in different positions, engaging different valves but the result is the same, unable to rotate the camshaft.

Before dismantling, measuring the valve clearances, the camshafts rotated by hand ok.

Any ideas anyone? I’m not sure if the cam followers are jamming in the housing.

Would it be ok to rotate the end of the camshaft with a spanner.

TIA G

[Pete Boole]

I wrap an old belt around the cam wheel to rotate them - you should be able to turn them by hand like this. If you use a spanner make sure you turn them clockwise!

Pete

[rbgosling]

Yes, it should be possible to turn the camshaft by hand - there's a fair bit of resistance when you are opening valves, but not difficult. You mentioned oiling the tappets and the valve stems, I assume the cam bearings are also well oiled?

What is the crankshaft orientation? If any cylinders are at TDC then valves could be hitting the piston top, preventing the camshaft from turning. I've never had problems with tappets jamming in their cylinders when I've done my engine. Are you using magnets to hold the tappets in position when you put the cam housing down onto the head, as recommended by the workshop manual? And then removing them before you try turning the camshaft?

[Gray14]

Ok, I think it’s just me being a bit over-cautious about how much force is needed to turn the camshaft.

Yes, cam bearings topped with oil, got oil everywhere. Heads off the car.

I checked there were no loose nuts, magnets or washers stopping it and turned it with a spanner and it rotated ok.

I also used the torque wrench that I using to bolt the housing down with and was surprised it takes 20 Kn/m, the setting for the housing nuts, to rotate the cams.

Seems a lot for the cambelt to take, albeit with it’s Kevlar core.

[Alan_M]

[quote=Gray14 post_id=108765 time=1746621084 user_id=20589

I also used the torque wrench that I using to bolt the housing down with and was surprised it takes 20 Kn/m, the setting for the housing nuts, to rotate the cams.

Seems a lot for the cambelt to take, albeit with it’s Kevlar core.
[/quote]

I’m no physicist, but I don’t think it will take the cambelt 20kN/m to turn the camshaft. The cambelt has advantage due acting at radius from centreline where the bolt is

[Marten]

I also used the torque wrench that I using to bolt the housing down with and was surprised it takes 20 Kn/m, the setting for the housing nuts, to rotate the cams.

Seems a lot for the cambelt to take, albeit with it’s Kevlar core.

I’m no physicist, but I don’t think it will take the cambelt 20kN/m to turn the camshaft. The cambelt has advantage due acting at radius from centreline where the bolt is

If you've fitted the camshaft wiithout, valves, springs etc it should turn freely. If you are turning the camshaft against followers and valve springs you'll get quite a bit of resistance