Laddis

Doing the timing belt, water pump and the tensioner for the first time, the time has come to attach the new timing belt. Driver side camshaft has moved 2 teeth counterclockwise, but can easily be handturned back to the mark. Passenger side camshaft had been rock steady at its mark, but when trying to fit the new belt, the teeth didn't match 100% so I thought I should nudge it a bit. Then CLICK the camshat jumpet about 10 teeth or so counterclockwise. With great effort, using the old belt to pull, I pulled it clockwise agin, but with the same CLICK as it passed the mark and ended up 10 theeth too far clockwise.

When looking into other TB change procedures I have found that my 45 deg marks are not at the same plce as the once on pictures. I quite sure I dod not turn the cranck 1 and 7/8th turn from TDC but only 7/8th of a turn.
1. Where does that leave me with the valves and the pistons?
2. Shall I remove the distributor rotor ang turn the passenger side camshaft clockwise until it ends up at my mark , or
3. Shall I turn it counterclockwise again 10 teeth to reach my mark.

Thanks.

Hilton

1. Which way up are the timing mark numbers on the harmonic balancer? They should be the correct way up when read standing in front of the car. If the numbers are the right way up and you're at the 45 degree mark, then you don't have to worry, and there has been no contact. The valve springs are strong, and will move the camshafts pretty hard.


2. The camshaft should be held in position by just the main center cam gear bolt, so you'll need to loosen more than just the rotor bolts (altho' they do add to the clamping force.

If you remove the distributor rotor and look in the slots in the cam gears where the bolts go, the bolts (and holes in the spider behind) should be pretty much in the centre of the slot. If they're at one end, then your cam gear isn't timed properly and that would explain being off more than the standard 3 teeth from the TDC mark on the cam gear.

To fix it either use Porken's 32'vr tool, or the factory method of using a dial gauge. If neither is an available option, just eyeballing it in the center will be within 2 degrees of correct in my experience.

3. Turning them clockwise is the only sensible way to go - otherwise you run the risk of loosening the cam bolt which is a problem.

Laddis

Thanks.

1. The Flywheel lock is in and the pointer was at the 45 deg mark on the damper. But I only turned the crank 7/8 ths and not one full round first. Which means my camshaft TDC marks are somewhere at 5 o'clock. When the TDC marks on the damper and camshafts are aligned, it is for the compression stroke TDC or Exhaust stroke TDC? As far as i can think (which is not far when it comes to V8 engines I must admit) the 45deg position on the crankshaft should be a non-interfering position regardless if the cams are 180deg off?
2. I don't think there is anything wrong with the camgear posiotion on the shafts. I just need to get to the hex washer and not the bolt to turn the camshaft, is that it?

Hilton

That's correct - use a 30mm ring spanner to turn the washer (its the only 30mm fitting on the car from memory).

Here's a picture of where it sounds like you are - TDC on cylinder 6. This is from my first TBWP on a 928, years ago.

Mrmerlin

FWIW when the engine is at TDC both of the rotors will point to the left fender.

NOTE the rotors can only fit on one way

NOTE The crank will be at TDC when the keyway is at 4 O clock.

NOTE the crank will be at 45 BTDC when the keyway is at the 3 O clock position

The cams will be 4 teeth before lining up when the engine is at 45BTDC.

When the crank is at 45BTDC then cams can be rotated in a complete revolution and the valves will not contact the pistons

NOTE the crank damper is positioned correctly when you can read it while Facing/looking at the engine,
If the numbers are upside down then it is on backwards and needs to be flipped around.

Laddis

Thanks.
Hilton thats exactly my situation, except that my PS camshaft has clicked 10 teeth counterclockwise. See pictures.

So: 45deg on the crank is "safe" nomatter if it got there by turning it 1 and 7/8th turn or only 7/8 turn? I think yes since the pistons are in the same location.
So then why do all the procedures specif that you have to do the 1 and 7/8th turn to get to the safe 45 deg mark?

Adk46

Good question. Perhaps it is exactly your problem of finding valves in a position that makes the camshaft move. My experience (with 1 and 7/8) was just as others have described: the port-side camshaft didn't move at all, while the starboard camshaft moved about one tooth CCW. Nice.

I noticed in Dwayne's tutorial that the "1" in the 1 and 7/8 business could be easily missed. That is, I almost missed it.

You shall overcome!

Hilton

Yes, 45 degrees on the crank is safe no matter what, as you're right, the pistons are in the same place.

When turning the crank to check the new belt, assuming you were at 45 BTDC on cylinder 1, you need to turn all the way around 1 7/8 crank turns (which is almost 1 camshaft turn) back to TDC, otherwise you're checking the belt tension at TDC on the wrong cylinder in the firing order, and the valve spring pressures are not the same as at TDC on #1.

In your case, once the cam is back on the right tooth and the belt is back on, you'll only need a 7/8 crank turn to get to TDC on cylinder 1.

BTW - my own experience of my first timing belt job mirrors yours, I had one of the cam shafts rotate round under valve spring pressure. If you do the job at #1 TDC, they're much less inclined to do that (I've done a few timing belt jobs since then on my other 928's)

Laddis

Thanks Hilton. I now unbolted the rotor on that camshaft and turned it with a 30mm wrench so that the mark is aligned again.

i guess that the cams are slightly less loaded on the cyl 1 45deg BTDC position as you mention. Thanks for the advice on checking the tension at that position.

My next problem is that i cannot seem to get enough belt slack to get it around the tension pulley. I starded another post on this...