How do I find TDC on a 77 bus standard engine?

I lost the end of a pen in my last attempt to find TDC and this was because the spark plug enters the cylinder at a perpendicular angle. Hence putting a pen in the cylinder results in it becoming trapped (and broken ).

My last bus, '71, you could put a pencil in the plug hole and the advancing cylinder would push the pencil out and when it reached TDC the pencil would stop etc etc.

My next task is to find my timing mark measured from TDC (there is no timing mark on the case)

Hi

Do have a 2 litre? Well supposing you, the timming scale has TDC on it, line up your timming mark to the 0 marking and then check where your rotor is pointing, that will be TDC on the cylinder.

The reason you broke your pen is because the plugs go in at a very shallow angle to the piston on the Type 4 motor, unlike the Type 1 engine.

1302Steve

Cheers mate, yes its a 2 litre

My problem is that I dont have a timing scale on the case or attached to the case. I only have a mark on the front side of the pulley.

How did anyone time the bus previously? I have no idea, can this be done with a timing stobe light?

[Edited on 12-3-2004 by 4 of 50]

I have the same problem on my bus (no timing mark) which I work around by having a mark on the pulley which lines up with the join between the case halves when the timing is correct. :thumb

Use the pen trick again, but as you turn the crank, use the pen to feel where the piston is. Don't just let it sit there and hope the piston will push it out.

Hi

I think you need to buy a timing scale, the last one probably got wiped out by a fan belt breaking I guess. When I worked in a VW shop, I often found that when tuning regular customers cars that after changing and setting the points the timing did not need to be adjusted. You will also need to find out where your timing is supposed to be set, from memory 7.5 BTDC on a single vac dizzy or 5 ATDC for a twin can, maximum measured on the timing scale with vac lines disconnected should be 32 degs total when you rev it up to about 2-3000 rpm.

Another thing I always found was that after changing the points and running the car for about 15 minutes the timing would retard about 5 degrees, this was caused by the rubbing block on the points scrubbing in, after this initial retard the timing on retarded itself a tiny amount as the rubbing block wore.

1302Steve

Cheers fellas

Is it possible to time by ear if you know roughly where the timing mark is to begin with?

I have the mark on the case I have made by using a static light when the no.1 cylynder is @TDC (plastic in the hole mark)

I will look into getting a new scale, thanks



[Edited on 13-3-2004 by 4 of 50]

DO NOT DO IT BY EAR!!!!!


It will end up too far advanced.

Find TDC then mark the pulley.

Find out the timing spec for your engine/dizzy combo.

Draw that angle on a piece of paper (ie 7.5 degrees) and measure the distance between 0deg and your timing spec at the same distance out as the radius of your crank pulley. Mark this on the crank pulley and time to that mark if you use static timing method. Ideally draw 32deg and mark that too so you can check full advance with a timing light. Nail polish is good to use to do the marks. Draw a diagram of the pulley with the dots labelled and stick it under the engine hatch so you dont forget what dot was what.


kkk

That is all sensible stuff thanks.

I will try to find TDC with a peice of wire and go from there.

here is the thread of my first round of timing mark questions for anyone who is in the same boat

Import Advantage, Brisbane 07 33576966

...you may be able to get the plastic bolt on timing mark from these guys.