Valve timing setup

[doffo25]

Im a bit confused about valve timing setup.

I set cylinder A1 at TDC and could insert a cam setting tool in the slot. However in this position I noticed that on bank B the cam slot is about 1 sprocket tooth out (and cylinder B1 is not at TDC)

Is my timing out?

Thanks

David

[MarekH]

Yes, your timing is out - you should have addressed this a fortnight ago, instead of pulling the heads.

Measure your valve timing first.

There might be a simple reason why one bank is different from the other, e.g. one camshaft isn't at the same angle (at cylinder 1A TDC) as the other. There is nothing unusual about the intra-bank variation. Your main question ought to be "why is A consistently lower than B?". Use the cam timing tool to check where the cams are when cylinder 1A is at TDC.

...

kind regards
Marek

EDIT:- If your cams turn out to now be subtly mismatched to each other, take a look at https://www.jag-lovers.org/snaps/snap_v ... 1381505777 and see whether your timing chain is how worn and stretched.

The B bank is 60' askew of the A bank, so where 1B is has no bearing on setup of the camshafts.

Since you are where you are, rotate the crank forwards to put cylinder 1A (front right) to TDC. Fit the cam tool to the A bank camshaft. If necessary, disconnect the two piece A camshaft sprocket via its circlip and adjust the A camshaft until the tool fits, then reassemble the A sprocket. Now disconnect the two piece B camshaft sprocket and adjust the B camshaft until the tool fits, then reassemble the B camshaft. Lastly, verify that the jackshaft sprocket and chain are positioned to make the distributor rotor fire 1A spark plug when you are at 1A tdc on the compression stroke. (That's the purpose of the jackshaft retaining tool.)

Now, if you haven't already done so, address the Nov 8th question of how B got to be so mistimed to A. The likely answer is timing chain stretch, so if you assess how far across the tensioner/chain sits by comparing the previously posted pictures of an old chain versus a new chain, you may need to roll on a new chain at the master link and then go back one paragraph to once again make sure both camshafts are squarely pointing up when at 1A is at tdc.

The pictures come from a snapped timing chain tensioner repair. Replacement of the tensioner involves taking the timing cover off.

kind regards
Marek

[MarekH]

Just so you understand, the tiny vernier teeth between the two parts of camshaft sprocket are off-set against the four mounting holes for the camshaft. This means the inner part of the sprocket fits multiple (8?) ways against the outer half and this how you reconcile and eliminate any mismatches between the crank and cam. (Obviously, the number of tiny teeth is not a multiple of four.)

kind regards
Marek

[doffo25]

Thank you Marek!

Best

David

[lowact]

Is it possible that someone has moved the timing mark scale (& subsequently messed with the A bank sprocket)?
If so, since B compressions are good:
Rotate the engine until the cam timing tool fits on the B cam.
Adjust the timing mark scale (position) to indicate that this is the A1 tdc position
Disassemble and reassemble the A bank sprocket so that the cam timing tool fits on the A side also ... ?

[doffo25]

Hmmm...that's another way of looking at it. However, when the timing mark is on TDC on A1 cylinder, the A1 cylinder is at the top of its stroke.....