Engine Timing

Phil Robson

Well-Known Member
#1
Please forgive my next 'Noddy' question :rolleyes:...

I've been setting the timing my 2000's engine with a strobe connected to No. 1 spark plug lead. I have marked the pointer under the flywheel inspection cover & have also marked the position of 4 deg BTDC (I think!).

Presumably this is when the timing is correct:

IMG_4162.JPG
and this is when it's not (too advanced in this case):

IMG_4163.JPG

When I rev the engine, the mark on the flywheel moves downwards out of sight. Is this correct, or is the vacuum advance on the distributor not working as it should?

I've still got a 'pinking sound' at getting on 3000 rpm (ie: about 55 - 60 mph on the road in top & at a lower speed in 3rd). Otherwise, the engine sounds good.
 

roverp480

Active Member
#2
Your second picture shows the mark after the pointer, if the points are opening at that point, the timing is retarded. As the timing advances both with centrifugal and vacuum, the mark will move further and further in front of the pointer (Downwards) as you have mentioned.
 

harveyp6

Well-Known Member
#3
The mark moving is the mechanical advance working, not the vacuum advance, (vacuum only comes in on light throttle and the overrun), and that's how it should be. The pinking, if it is indeed that, may mean that there is too much mechanical advance at higher rpm. You can combat this to a certain extent by retarding the timing at idle.
 

colnerov

Well-Known Member
#4
The mark moving is the mechanical advance working, not the vacuum advance, (vacuum only comes in on light throttle and the overrun), and that's how it should be. The pinking, if it is indeed that, may mean that there is too much mechanical advance at higher rpm. You can combat this to a certain extent by retarding the timing at idle.
Hi, Which probably explains why the mark is where it is.

Colin
 

Phil Robson

Well-Known Member
#6
Many thanks guys, I think I understand it a bit better now :)

What I did notice was that the mark I'd put on the flywheel was actually at 6 deg BTDC, not 4 deg:

IMG_4178.JPG

The arrow is pointing to the number "4" marked on the scale, so I've changed the mark to there & altered the advance/retard on the distributor to get the mark around where the fixed pointer is. It does vary somewhat in that it seems to 'hover' around the pointer a degree or two on either side when lit by the strobe. I presume this is normal, or do you think it should be steadier?
 

Phil Robson

Well-Known Member
#7
Here's a close up of the scale on the flywheel, for those who haven't seen one before:

IMG_4178a.jpg

The marks have now been cleaned up & amended :rolleyes:
 

cobraboy

Well-Known Member
#8
Before you start timing any engine you need to establish if TDC on the pointer is actually TDC.
Use a piston stop inserted into a plug hole and gently turn the engine over by hand until it stops and then mark that point on the flywheel. Turn the engine all the other way until it stops and mark that position on the flywheel. Exactly half way between the marks is true TDC, align your pointer with this.
Now you can set your timing. I set mine all in - 32-34 degrees ( on a v8 ) at around 3250-3500 rpm and it is whatever it is at idle, although if you get pinking you have to retard a little.
Main thing is to establish true TDC.
 

harveyp6

Well-Known Member
#9
It's a lot less likely that the pointer & TDC mark on the flywheel will be inaccurate.

Thinking about it, it's pretty unlikely that the 2000/2200 marks on the pulley and their pointer are going to be out of line either.
 
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