Camshaft Timing

XK-Engine
1

At last the Cylinder Head is on and bolted down.

I have a question relating to camshaft timing. When the head was removed I noticed the Inlet Cam did not line up exactly with the cam timing tool. Figured would sort this out on reassembly.

The Inlet cam is out about 1/4 of a bolt hole, see attached picture. The shop manual (for me at least) is a bit vague as to how to make an adjustment. From my understanding tighten the cam eccentric, reinstall the four screws, then remove the large clip move the sprocket around to line up with the bolt holes…making sure the cam is in the correct position.

The engine has not been rotated and is lined up with number 6 piston at TDC, position has not changed since removal of the head…

Is the above procedure basically correct…or?

Jag-Timing
Jag-Timing1495Ă—1419 335 KB

Thanks

2

No, remove bolts, remove circlip, pull out plate, line up cams, match bolt holes. If off by half a tooth, turn plate 180°. Install at least one bolt and turn the engine over to recheck. Install circlip and bolts.

So mostly correct but you have to remove the bolts so you can pull the serrated plate out and match it up with the bolt holes.

2 Likes
3

davisdsxj6 is absolutely correct… I will add hand turn engine and rock to CW direction so as to remove any slack in the timing chain. The book is correct.- make sure you get this one right. keep asking if you need to.

1 Like
4

Removed the bolts and the circlip, tried to separate the plate by pulling the outer edge forward (by hand) however cannot separate, seems to be locked on solid. Have sprayed some penetrating oil (WD 40) around the serrations that I can see. Tried to gently tap, still no movement.

The car was on the road before the head removal, so plenty of oil, no corrosion around the parts.

Any thoughts on next steps

Russell

5

I’m not sure what you’re calling the outer edge. The outer edge of the adjuster can’t be touched until it’s out because it’s embedded inside the gear. It can be difficult to pop out the serrated adjuster if it’s under pressure, kind of like trying to turn an ignition key if the wheels are cocked and putting pressure on the wheel lock.

Slacken the chain and try again. You might have to back off the crank slightly to remove pressure from the exhaust side (just nudge it a couple degrees). Assuming the adjuster has a center spindle on it you can tug on that and wiggle it to and fro. If it’s a new chain or very tight, you might have to tap the gear off the cam end to create enough slack. Be gentle so you don’t bork anything. Be careful reengaging the plate to ensure that all the teeth are squarely engaged and it’s fully home before torquing down on bolts, otherwise you’ll ruin the teeth.

Be especially careful to not allow either cam to rotate by itself or you’ll be pulling the head off again with bent valves. This is an iterative process. You might be pulling that plate out 10 times before everything lines up perfect and remains perfect after it’s all together and you spin it over a couple times to test the accuracy.

Also, don’t get careless and drop something into the cavern. It’s good practice to stuff a rag in each time you go near with a small part.

1 Like
6

Then WD40 will not do much. Try what Erica writes. Tap off the sprocket with a soft faced hammer. Tap it off straight, with tension on the chain relieved. Once off you might be able to tap the sprocket off the plate. They bind sometimes.

The cams can move a little, don’t panic. If it turns by a few mm it will definitely not cause damage. You will have to try a few times until it lines up and you will have it far easier if you stuff some rags into the abysses.

7

Have taken the tension off the chain, with the tensioner and the sprocket is off the Cam, did all of this day before yesterday.

Now have a small nylon faced hammer, the plan is to hold onto the centre of the plate and tap,
gently around the outer (chain) edge, toward the engine. Hopefully the centre plate will separate.

Russell

8

You could put the bolts through, stick some washers on the back side and then bolt it back onto the cam. Now when you tighten it up there will be an air gap between the assembly and the cam and you can lightly tap around the outside gear until it pops off the teeth. One it does, take the opportunity to clean the parts well. There is likely sludge binding them together.

edit if you do this, make sure a catch rag is in place so the washers can’t drop down. Also tap using a brass drift so you aren’t banging on the chain. You might first try disengaging the entire gear assembly with the chain at full slack, so you can bring it over to the bench and take care of it there. Sometimes there’s a lot of sludge or filings in the teeth, or a tooth has a burr from rough previous assembly that needs to be filed so it works smoothly again. It might be necessary to unbolt the cam to make room for removal.

1 Like
9

Try from the camshaft towards the front and knock the chain forward, then when it’s off you can separate the plate. A temporary washer between plate and camshaft sounds good!

10

Great idea to put some washers between the plate and the end of the camshaft…will get to this in a couple of days. In the meantime will continue to work on the rest of the work reinstalling the head. Pipes, hoses and carby’s

Will post the result of the suggestion…reckon this should work.

Russell

11

Russell,
You don’t want to drop anything like washers or tools inside the timing gear. I always stuff a bunch of shop rags in every imaginable place that a small tool or loose part could fall into whenever I am working in that area.

Paul

12

Finished adding all the bits to the engine, carbys, dizzy hoses etc etc.

Attempted to get some washers behind the plate, however not enough space. Keeping the plate near the end of the cam there is very limited space. Had another person hold onto the outer edge (chain) and lightly tapped the plate outwards (toward the front of the engine) with a piece of 1/2 inch copper pipe used as a punch, without success. The parts seem to be locked together, solid.

Using the marks on the harmonic balance plate I measured the position of the inlet cam when the slot in the cam is in the correct position. It is 12 degrees ATDC, which equates to 6 degrees of cam timing.

Calculated by measuring the distance between the TDC mark and 10 degree BTDC mark around the permitter edge at 20mm (approx), so 2mm = 1degree. Then measured the position on the crank pulley when the inlet cam slot was lined up correctly, this I measured as 24mm, which equates to 12 degrees

If my calculation is correct the inlet cam is late by 6 degrees.

Before the head work, the car was driving OK, and when removing the head I noticed the cam timing was out of sync. Now with the work completed, new reseated valves , etc I am reluctant to crank over the engine. However, I have turned ithe engine over manually using a spanner on the crank pulley, and everything turns OK.

Any other suggestions regards separation of the plate and chain (sprocket)…or is the 6 degrees of late Inlet valve timing ATDC not going to make a much difference???

Paul, yep I am extra careful when working around the front of the cams. On disassembly, without thinking clearly I snipped off the safety wire and a piece dropped into the “cavern”. Luckily the piece landed on a bit of a ledge, so using a magnetised screwdriver was able to extract the piece of wire…sometims luck is on your side, also learnet a great lesson.

Russell

14

Hi Russel…have you actually removed the camshaft and then tried to remove the sprocket and serated plate so you can get it on the bench…you might have to remove both cams so that both sprockets can be moved and possibly turn crank slightly to slacken the chain…Im sure i remember getting these out…personally i wouldnt be reassembling with the cam timming incorrect…Steve …ps think about rigging up some kind of a press in situe to press the serrated plate out…a couple of bits of plate and bolts( or a small 3 leg puller on the back of the sprocket tonpush iff the plate)…also consider someone may have used locktite or similar…so a gas torch to heat the area is worth a try

1 Like
15

This is what I’d do. It’s usually not a big deal because timing goes along with setting valve lash so the cam is going in and out half a dozen times anyhow. I don’t think the gear/adjust assembly can slip out of the chain to the front because the aluminum housing is in the way but I think it can come out easily if the cam is removed. I don’t think there are any gotchas to removing it other than nuts and washers dropping into the oil returns. Put rags under the cam to cover them. Loosen the nuts evenly and cup your hands over in case the valve spring force wants to make something pop. You’re at top dead center…or should be, so it’s easy to reinstall it correctly. Have some new marked baggies ready to receive the bearing caps. Put the caps back in the same place. They should be stamped with the number.

On the bench you can soak it in parts cleaner and work out a way to push the two things apart gently. They probably haven’t been apart in half a century. Some ham fitted mechanic might have used the bolts to drive the adjuster into place and boogered a bunch of teeth. If so you may be able to touch them up with a tiny file. Worst case they can be replaced. They shouldn’t fight you like this. Mine come apart with a gently even nudge.

1 Like
16

On my engine one was very difficult to remove, thought it was rust but it was a burr on the sprocket.
A ½” copper tube tells me you guys are most likely too careful with it. If you can remove it from the chain that is your best bet. But if it’s that loose I’d keep following the washer sandwich approach.

17

Success at last!

Removed the cam and tried several times to slip the sprocket off the chain, however not enough space to maneuver the sprocket successfully. It is possible (quite easy) to move the chain around the sprocket, one link at a time. I marked both the chain and sprocket so it could be returned to starting position. There is a small circlip and some type of spring washer at the back of the shaft which goes through the plate…likely this could be removed, then remove the axle and the chain off the sprocket. Attempted to remove the circlip, without success.

It was looking like the head would need to be removed in order to get good access. Then tried one last time with a large brass drift and an engineer’s hammer (about a pound and half), and with assistance of another person holding the sprocket hard up against the head, a decent hit on the plate toward the front of the engine and the parts started to separate…couple of more hits and it was free.

Thanks for all of the suggestions

18

Nothing quite as effective – and as satisfying – as a good percussive adjustment.

:+1:t2:

19

Well, I uncorked the champagne a bit early.

After separating the plate from the sprocket tried to reposition the plate, however it would not seat correctly. So removed both the sprocket and plate from the car. As Erica mentioned in one post, looks like some previous ham fisted mechanic used the bolts to align the plate and cam. About a quarter of the teens on the plate are burred…hopefully I can tidy these up with a small file. Otherwise it looks like a new / used plate will be on the list.

Very frustrating, as except for this next fix the car is ready to start and drive, following the head job.

Russell

20

Bummer but at least it’s apart. Can the gear be savaged? The plate isn’t too expensive I don’t think.

21

You will be very fortunate if you are able to dress the burred teeth. It might be a better idea to replace both plate and sprocket.