cam clearance?? how much friction?

[el-saturn]

my motor man with all the infra structure and I have differing opinions: I don?t like the "handfull" it takes to turn the cams; inlet is less tight than outlet and both take the normal jerk BUT especially the HOT side takes a pretty healthy grip to turn it - should we get a reamer to the bores???? what do you experts think: HOW "SOFT" a grip is adequate OR what?s TOO much?? hope to feel better in a few hrs!! sandy 36/4982

[rgh0]

Cam should spin freely in the bearings with no valves and buckets installed.
Buckets should slide freely in the sleeve bore and be within the manual clearance specifications and and the bucket sleeves and buckets straight and unworn.

All resistance to turning should be coming from just the spring loads. Do not turn one cam with the other cam installed on an assembled head as the valves will clash and you will bend them.

regards
Rohan

[RichardHawkins]

Sandy,

I had a tight cam shaft, it was not straight. I suggest it is worth checking. A decent engineering workshop should have the facilities. The shaft either needs to be rotated between centres or in vee blocks whilst a dial test indicator is held against the bearing surfaces. As Rohan says a straight shaft should turn freely in the bearings. Don't ream or do any machining work to your cylinder head until you are sure of the reason the cam is tight to turn.

Richard Hawkins

[el-saturn]

thanks richard and rohan!! the head is back at the shop where my man will measure everything and thereafter will "make the adjustments". should be finished this afternoon cheers sandy