Cam Slots

[911/Q45]

Why do the camshafts have reliefs machined into them to provide access to the head bolts? I can't come up with any scenario that involves the head bolts without removing the valve train first.

[DAEDALUS]

That sounds like the most plausible reason. Not conviced it allows enough access to the rear bolts though, but if not, then how odd. It's much easier to disassemble the head on a bench rather than under the hood. If you had to replace rings or a head gasket, you might decide to leave the valves alone, though I agree the valvetrain needs more attention overall than anything in the block usually. Are you in there now?

[911/Q45]

Not in there now, thank goodness. Just ruminating on things I saw last fall during my marathon session.

[forecast]

The slots are there for the installation process.

The valves need to be on and tightened down before the head is torqued down.

I did pull the heads with the cams in place, but it's risky because you can easily bust a valve handling the head.

[911/Q45]

If you're saying the cams need to be on and tightened down before the heads are torqued, why would that be?

[forecast]

yes,

the book said to

set the block to TDC on #1lay the heads on the blockrun the head bolts down finger tightinstall the HLA's rockers/ cams (tight to spec)fit the cam sprokets, chains, tensioners and timing coverstorque the head bolts (four stage method)

I THINK this has to do with any slight warping of the head that might occur as a result of the cams being torqued down.