aggravation

Here, I found a pic I took after locking the flywheel, but before removing the belt.

UKKid35

Initially I thought you could tell from the position of the rotor in your picture that the crank was at 45BTDC, now I'm not so sure....

It doesn't look as if it is exactly 180deg off the position shown in Wally's write-up...

I'm starting to think that the crank is at the TDC mark - 0|T

aggravation

I don't see how that could be, the crank has a key on it and I've slid the balancer back on to check and it is definitely showing 45....due to the keyway in the balancer it only slides on there one way.

UKKid35

You must be right. The two pics are taken from different angles which makes them difficult to compare. Looking again at the photos the notch in the cam in your pic does seem to be 180deg from the notch in Wally's pic. I was trying to compare the angle of the rotor arm, but the notch is a much more accurate indicator.

mark kibort

is it possible to retrofit that support bracket to the idler arm on the earlier pre-84 type water pumps and tensioner attachments? i have the S4 type ARM, but 84 pump with S4 tensioner and senor wires.

Garth S

From the pic, ypu are exactly 180 deg off on the cams - reread through my posts, and perhaps all will be clear You can then advance the cams so their notches are 3 teeth before the backing plate indexes, rotating clockwise: with the TB restrung at that position, remove the flywheel lock from the 45 (BTDC) position, and then a slight clockwise rotation will have you back to O/T on the crank - which is true TDC . The cam gear notches will be smack on their index marks:.
Then, you can do the fine tuning with Kens tools.

Hilton

From your pic, you are at #6 45º - you can tell by the direction the rotor points, and also the notch on the front of the original sprocket.

Its fine for installing the sprockets, but you'll want to check the timing once you've tensioned the belt and hand-cranked a few times, at TDC.

I did the same for my TBWP job a few months back.

If you look at the timing belt cover, you'll see that in addition to the cylinder numbers embossed on it (where they plug into the dist. cap), there's an arrow that points towards the rotor from TDC on #1.. its near the 3pm position relative to the hole for the rotor.

PorKen

Why bother?

aggravation

Thanks guys,
Just for clarification, generally speaking, if the crank is locked at 45 deg BTDC and the cam sprocket notches are both sitting 3 teeth before the backing plate reference marks, then the cams would be timed correctly and if I then rotated clockwise, both or either cams, 360 or 720 or 1080 degrees, they would still be timed correctly?

Likewise my cams, which were sitting at 180 degrees away from being 3 teeth BTDC when the belt came off can be advanced the 180 degrees, plus or minus the distance the cams moved as a result of the belts sudden release, and then my cams would also be timed correctly. Then remove the flywheel lock and advance the whole arrangement the small amount clockwise which should put everything at TDC, balancer mark showing O/T as well as the notches in the cam sprockets lined up with the reference marks on the backing plate for the final timing adjustment?

So when the crank is locked at 45 degrees BTDC, regardless of what stage of the cycle the cams happen to be sitting at when you locked the crank, if you rotate the cams 360 degrees they and the valves are right back where they were when you started the rotation. Unlike the crank, which must make two 360 degree rotations to put the valves through one complete cycle, the cams travel one 360 degree rotation to complete a cycle as far as the valve timing is concerned.

Are those statements correct? If so then the mystery is solved for me and probably any other newbie reading this in the future will be able to wrap his mind around the valve timing scenario.
Thanks!