I took off my head for rebuilding and it is now reinstalled after putting #6 piston at ttc on compression stroke and cams in correct position. So I am now ready to connect timing chain sprockets to camshaft and I am not experienced and am nervous about getting this critical step right, even though I have read and re-read both the original Jag and Haynes maintenance manuals. So would appreciate your confirmation or correction of following proposed steps.
As the cha in moves a little back and forth, my first step will be be to rotate the serrated adjuster ccw until chain is reasonably tight and does not rotate.
Then remove clips from sprockets, shift out The adjuster plate until holes line up with holes in cam.
Insert one setscrew.
Then, and this step which will make me most sweat, rotate engine so I can insert second setscrew
Finally rewire the set screws.
Is this the right sequence and, if so, what is most critical step?
I would keep some slack in the chain or you’ll find that you can’t get the sprocket to fit onto the cam.
You need to rotate the engine because you can’t access both holes at once. Once you have the sprocket correctly seated on the vernier and one bolt snugged down nothing can move.
To get this to work you need to have the holes in the cam and the vernier EXACTLTY right. It is sometimes possible to get the bolt to go in and start in the thread even though you have the vernier slightly cocked and not correctly seated. The bolt should thread in easily by hand. If it doesn’t, stop and ensure that you really so have the holes perfectly aligned.
Take your tlme and use a good torch to ensure that the vernier is seated all the way around. DO this by checking that it is equally deep in the sprocket all the way around. Don’t forget to stuff a rag in the top of the timing void so you can’t drop things down there.
May I suggest you set the intake cam at 4 deg BTDC and the exhaust cam at 2 deg BTDC. This way the cams will be correct after break in. This is how much mine were out at 1000 miles. I do not think being slightly advanced in the beginning will be noticeable.
While I understand what Bill is saying I would just set the cams at factory, which is what I always do…
The amount of change in timing you get even if you have a huge amount of slack in the chain to start with is small and probably won’t be extreme enough to objectively affect performance.
Furthermore the effect isn’t predictable; it depends entirely on how much slack you have, and where. So while Bill’s experience was 4 and 2 degrees, yours might be different.
Once you get one bolt in each cam plate, rotate the crank TWO whole turns to bring the cam notches back up to TDC. Sneak up on TDC. Now you can assess how much retard there may be in the valve timing. This will also allow you to tighten adjuster/chain to the proper slack since all slack will now be on intake side, advancing the intake cam in the process.
I’ll add a couple points to the answers you already have
Shove a rag into the cavity whenever you are fumbling with bolts or wire. It’s very easy to drop something
It’s unlikely that the cam gear vernier adapter alone gets you to perfect bolt alignment. It can happen, but it’s hit or miss. More often you’ll stab around with that verier adapter several times but the bolt is still slightly canted to the side. As Andrew points out, that’s not going to cut it. You should be able to thread those shoulder bolts all the way in with your fingers. If it requires a wrench them you are rotating the gear away from the correct timing in the process of tightening.
So in that situation you slacken the tensioner again, pop the gear off, and rotate the gear a single tooth on the chain. Then reverse the steps and try stabbing again with the vernier adapter until the bolt goes in cleanly.
Before testing I like to know that all chain slack is removed in the direction of rotation. It doesn’t matter if there is some slack on the other side. It only turns one way and that is the direction you are timing for. So after mounting the gears on the cams, I’ll rotate the crank backwards a few degrees until the cams just start to move, and then go forwards to TDC. Then verify the cam orientation again with the tool. Now all three parts are at TDC, and the leading chain segment is dead tight. Now test the bolts.
