TDC

[Maggo54321]

Can someone confirm these 2 white dots on the cam pulleys are meaning I’m at TDC on cylinder 1?

[fjmuurling]

Check the marking on the flywheel. It is behind a rubber cover on the TOP right side of the bell housing.

A second best option is the small notch on the crankshaft pulley.

Cylinder 1 is in TDC firing when the dimples on the camshaft pulleys are pointing to each other. 

[Maggo54321]

Thanks. I can’t get under the car so having to do everything from above unfortunately 

 

[TAR]

Remove the no.1 spark plug and out a long screwdriver into the cylinder, when you turn the engine over by hand you can see the screwdriver raise to it's highest position at TDC. This should coincide with the marks aligning  

[EXCEL V8]

The marks on the cam pulleys that have to be aligned are on the front of the pulleys - your photo shows marks on the rear.

Pete

[Escape]

Those marks look to be non-factory. Nothing wrong with that, as it helps to avoid timing issues when changing the cambelt. But as always, trust but verify! So don't just assume the markings are correct unless you put them there yourself. You really need to check the crank position AND verify the marking on the cam pulleys coincide with the factory dimples in the markings. This seems to be the case, but as mentioned this is the rear side, not the front one, which is the one that actually matters. so double check the dimples align there as well.

For the crank position, either look at the flywheel through the access flap on top of the bellhousing or, as above, use a screwdriver or similar to determine when the front cilinder (nr 1) is at the highest position. If you can't reach the crank pulley to turn the engine, put the car in 5th, jack up one rear wheel and turn that to turn the engine. Easier with all plugs out of course.

Also, what are you trying to do? Verifying timing as is, or preparing to change the belt yourself?

[jonwat]

10 hours ago, EXCEL V8 said:

The marks on the cam pulleys that have to be aligned are on the front of the pulleys - your photo shows marks on the rear

They're on the rear for Esprits & I agree with Fillip they're normally (green) paint filled dimples.

Edited June 4, 2023 by jonwat

[EXCEL V8]

7 hours ago, jonwat said:

They're on the rear for Esprits & I agree with Fillip they're normally (green) paint filled dimples.

You learn something every day!

Pete

[JimmytheTurbo]

20 hours ago, Maggo54321 said:

Thanks. I can’t get under the car so having to do everything from above unfortunately 

 

The timing marks on the flywheel which are the ones you have to use are from the top side. In the boot.

I remove the plugs. Jack one rear wheel put the car in 5th and turn the wheel to move the car to TDC

Once aligned then check the cam dots.

Edited June 4, 2023 by JimmytheTurbo

[fjmuurling]

11 hours ago, jonwat said:

They're on the rear for Esprits & I agree with Fillip they're normally (green) paint filled dimples.

or red or blue

[jonwat]

16 hours ago, EXCEL V8 said:

You learn something every day!

If they were only on the front then you'd need a mirror to see them on an Esprit. 

[Chillidoggy]

This does of course only apply if your red/green/blue paint hasn't long since disappeared, as they had in my case. Then you're back to the dimples.

[Escape]

Just to confirm, there are dots on both sides, sometimes with different colors (red/blue) to identify different timings (on the same pulley). You do need to make sure IN and EX are on the correct camshafts, as viewed from the front. This is the case in the picture in the first post.

I am still wondering about the reason: verifying timing or preparing a belt change, or maybe something else even?

[Maggo54321]

ok, so it turns out that both my cam pulleys have 'in' and 'ex' on them and viewed from the front of the engine, they are correct.  There is indeed a little dimple on the front of the pulleys which someone in the past has transferred to the back with the white dots, these are what I used to align for TDC.  I do have a little cut through on the flywheel bell housing, but it doesn't have anything obvious marked on it?

I'm doing this for timing check when fitting a new 123 Tune + distributor.

[JimmytheTurbo]

2 hours ago, Maggo54321 said:

ok, so it turns out that both my cam pulleys have 'in' and 'ex' on them and viewed from the front of the engine, they are correct.  There is indeed a little dimple on the front of the pulleys which someone in the past has transferred to the back with the white dots, these are what I used to align for TDC.  I do have a little cut through on the flywheel bell housing, but it doesn't have anything obvious marked on it?

I'm doing this for timing check when fitting a new 123 Tune + distributor.

 

You dont need a mirror.

I think front & back are getting muddled up in this thread.

Front of the engine is the end close to the steering wheel.

The dots you need to worry about are the ones visible from the boot (rear) end of the car.

The cam sprockets have in on one side and Exh on the other with dots in on each side for that use.

As you have the sprocket on the correct shaft you only need to think about the dots you can see looking from the boot end of the car.

 

Looking through the cut out in the bell housing you need to rotate one road wheel with the plugs out so the flywheel moves until you see the engraved TDC line up with the pointer.

Dots on cams should then be aligned but you may need to rotate the end another full turn to get them in the correct position...

 

 

 

 

[Maggo54321]

Right then I feel like I'm getting somewhere.  I've done what you've all recommended and I've taken a video of the flywheel inspection hole whilst rotating the rear wheel in 5th gear.  It's too big to upload here - but here's some screenshots of it.

I seem to have 40,30,20,10 and TDC marked on the flywheel.  And TDC exactly lines up when the 2 white dots on the cam pulleys line up too.

So I assume that I leave it at TDC and when fitting the new distributor, the rotor arm should be pointing at the HT lead going to the number 1 cylinder?  Surely it's not that simple? 

Would this be just to get it the engine started, then I tweak the distributor cap slightly with a timing light?

 

[drdoom]

TDC flywheel markings will apply either to cylinders 1 and 4, or 2 and 3 on an inline 4, and yours will of course be the former. Convention is to address the markings in terms of cylinder 1, and it is when its piston is in that general vicinity that sparking is to occur so yes, rotor pointing to that cap post.

[Maggo54321]

Thanks for confirming.  I seem to have 2 holes in the bell housing.  One small circular one (which I took the above video through, and one larger one) see pic below.  What is the larger one for and shouldn't it be covered up!  Hate to think how easily debris could get into that!

So is this rough TDC just to get the engine started, then I should get someone to tweak the timing properly with a timing light?  Or should I be using one of the 10,20,30,40 marks to line up for the distributor installation?

[JimmytheTurbo]

The hole in the bellhousing my earlier (1985) car has a pointer and as the pistons and crank are all connected and fixed,TDC marked there is 100% TDC

 

The white markings on the back (boot) side are they by the dot which is stamped in? Its sometimes easier to see with a bit of white paint.

 

On my flywheel I have a red dot of paint at TDC and a mark of white paint at 11% before to dead centre (I think) which is where I set the engine timing with a strobe light. Its not always that easy to see and read the markings with the strobe with the engine running but the paint makes it easier.

[Escape]

Good, you have confirmed the cam timing is correct. As said, the dots are on the same tooth front and back, so no need to confirm with a mirror (but apart from the effort, no harm in double checking 😉 ).

As for timing, on a carb turbo you want 9° BTDC static and idle, on an Bosch injection turbo that is 15°. The later Delco injection cars have electronic ignition control. So set the distributor to fire cilinder 1 according to the markings on the flywheel (just before 10 or haflway between 10 and 20) and then finetune with a timing light. It is always better to err on the safe side, i.e. too little advance rather than too much, as a starting point.