Can't find TDC marks

[cass3958]

Yes I know that cylinder 1 is the one at the back. This is on TDC according the mark on the pulley (and the check you mentioned with the screwdriver)
In this position the rotor of the distributer should pointed cylinder 6 according to me.
Is that right?

As far as I can remember and it was eight years ago that I timed my engine after the rebuild, if cylinder 1 is at TDC and the timing mark is pointing towards the marker on the bottom of the sump then the rotor arm in the distributor should be pointing at the HT lead that goes to that number one cylinder. The whole point of the rotor arm is to allow the spark to jump from the centre point to the HT lead of the cylinder that you want to fire. The timing of the engine means the spark will fire the fuel in the combustion chamber just before TDC. With an 8 to 1 compression engine this will be about 7 degrees before top dead centre. As Glyn has said some times you can put the distributor in 180 degrees out so the engine is trying to fire cylinder 3. When cylinder 1 is at TDC it will be on its compression stroke. Number 6 you have said is also near TDC but this one will be on its exhaust stroke.
If the timing mark is correct, cylinder 1 is at TDC but the rotor cap is pointing directly away from cylinder 1s HT lead you are 180 degrees out so turn the distributor 180 degrees and try again.

[Glyn Ruck]

Please note that I'm not talking about the drive dog being 180 degrees out.

On a Lucas 22D6, by removal of the central screw you can take the main cam lobe shaft piece out of the distributor with the weight plate and re-install it 180 degrees out. An easy mistake to make. This places the Rotor 180 deg out.

Distributor cam.JPG (175.11 KiB) Viewed 807 times

[HG_S-type]

Hi Rob, Glyn,

Thanks for the detailed explanation. I will check it again.
The reason why I'm confused about it is that the Haynes workshop manual of my E-type discribed the opposite.
I attached the Cylinder_numbers, firing order and Valve_timing part in that manual. There you can read that the No. 6 should in TDC.

It is confusing isn't it?

Regards,

Harrie

[cass3958]

They are correct in that they have numbered the cylinders correctly. They are also correct that if a cylinder is at TDC then the distributor arm should be pointing at the corresponding HT lead for that cylinder. I think the confusion here is that what they are describing is VALVE timing not ignition timing. The blue service manual for the S Type is exactly the same but if you go to page B48 there is a section on Ignition timing.

Now I am confused because I have just looked at this section B48 and you are correct that even the ignition timing is set off cylinder number 6 according to the book. As I said it was eight plus years ago that I set my engine timing and I am sure I did it off cylinder number one but I might be totally wrong and I apologies if I have miss lead you.

[Glyn Ruck]

Rob. We assembled the distributor cam ( & thus rotor) 180 deg out which is why I know from experience how to foul that up. Thought I'd blown a new silencer when we tried to start. The bang in a garage was huge.

IIRC you can time off of cylinder 1 or 6. Most time off 6 because of length of timing light leads.

My first restorer that I fired insists it's cylinder no 1 (rear). In fairness he has built one hell of a lot of XK engines. My Cape Town help uses No 6 to get our 7 deg BTDC. Seems to make zero difference. (with the Pertronix Ignitor you can't do static timing with a lamp. The engine has to be running with a timing light breaking the No 6 HT lead to the plug)

I have not examined the crank carefully to see if there is any difference. I don't think there is.

If in doubt follow the book.

[HG_S-type]

Hi Rob,

No need to apologies. I always appreciate your quick response.
B.T.W. I found the root cause of the confusion.
The distributor itself is ok. But when I took that out of the block I saw that the drive shaft position is opposite compared with the manual.
See attached pictures.
That's why it seems that the rotor is pointing to the wrong cilinder when 6 is in TDC.
I can turn the engine 1 cycle and remove the camshafts and place them back in cilinder 6 TDC position.
But for the moment T choose the exchange the numbers of the spark plug wires. So 1<->6, 2<->5, 3<->4.
Started the engine this afternoon and it runs well with less tapping noise as before valve clear adjustment.

Regards,

Harrie

[Norton]

Hi.
When timing ignition on a 6 cylinder engine it does not matter if you use cylinder 1 or 6. And not important whether no. 1 is at front or back. No. 1 and 6 are at TDC at same time, they move together, but fires alternately near TDC. But of course rotor arm ( whitch moves at half engine speed ) must point at the cylinder whitch are on compression stroke.
Harald.