Timing Chain Alignment on the M30

[myles]

Guys, I have a problem getting the alignment correct between the cam and crankshaft. The chain is always half a tooth out of alignment.

I had initially thought that it was that the old timing chain was stretched, but now with a new chain, tensioner and cam sprocket, the same problem exists.

I have checked the thickness of the head, and it is spot on correct at 129mm.

What have I forgotten about??

Would it be best to have the cam timing advanced or retarded half a tooth? (keeping in mind that this car pings and the timing was advanced half a tooth)

[winfred]

half a tooth shouldn't effect it enough to really matter, pick one and go for it, id go advanced

[joshua43214]

When you align the chain, rotate the engine backwards about 15-20 degrees, then rotate it forward to the mark on the crank. The cam timing is checked with the chain under tension in its proper rotating direction. Pry very gently on the tension rail to assist the tensioner in taking up the slack, or you can remove the tensioner and push in with a suitable tool to imitate tensioner pressure.

I don't think it is possible to put the cam gear or its drive flange on backwards on an M30, but worth having a fast look just to be safe.

[Kalevera]

Timing on the M30 is a bit subjective, as Winfred said. Make sure the HB point is accurate and get the cam sprocket as close to squared away with the head as possible. Not much more to it.


best, whit

[Rustam]

Guys, I have a problem getting the alignment correct between the cam and crankshaft. The chain is always half a tooth out of alignment.

I had initially thought that it was that the old timing chain was stretched, but now with a new chain, tensioner and cam sprocket, the same problem exists.

I have checked the thickness of the head, and it is spot on correct at 129mm.

What have I forgotten about??

Would it be best to have the cam timing advanced or retarded half a tooth? (keeping in mind that this car pings and the timing was advanced half a tooth)

Bentley's manual gives a misleading impression that the bolts on the sprocket have to perfectly align with the mark on the harminc balancer. This is not true - look closely and you will see that those bolts are not perfectly aligned with the diameter of the sprocket - they are not 180 degrees apart. This misrepresentation can translate into absence of half a tooth. Align the top tooth with the center of the sprocket paying attention to the pin dowel and the mark on the harmonic balancer. Once you find you need to adjust the positions move in the direction that takes smaller motion for things to coincide...

The engine is not designed for manual cam advance, I suggest you not to play with it.

[myles]

Thanks for the info guys.

Having had a sleep and got your info I feel better about it now.

I will let you know how I get on.

Cheers
Myles