Ignition Timing

[alanworland]

I have had the Morris setup as per the workshop manual for ignition timing ie TDC as set with a lamp across the points.
It has been suggested that the timing should be advanced to a point where 'pinking' occurs - then back a bit so when pulling hard there is none, sounds good advice.
Nearby to us we have a rather steep hill which will require second gear to climb it. The ignition setting was marked and advanced and the hill tackled, full throttle up the hill and the revs were falling! - but we got up! Ignition a bit more advanced and the hill tackled again, full throttle in second and the revs were again falling (fast) a quick double de clutch into first saw us arrive at the top!
On neither occasion was there any sign of pinking.
With the timing returned to its original position (TDC) the hill was tackled, and we powered up (in second) and could even accelerate, but not make third (showing the old Morris a bit of respect!)
So, what's all that about? I was of the understanding that by advancing the timing I would be able to establish the ideal point to optimize the burn in the combustion chamber and extract a bit more power.
I did even consider (still might) actually retarding the ignition and see what happens!
Any thoughts?

[katy]

How good is your hearing? If you were alone in the car during testing, it's possible that you were not able to hear the pinging.
I know that I cannot hear higher frequencies and usually cannot hear an engine when it's pinging, I need somebody with me to tell me if and when the pinging occurs.

[alanworland]

I've never not heard it before! (on other vehicles)

[MikeNash]

Alan,
This method is advocated by Our Scottish Friend (who I'm sure'll be along soon) but I suspect its best used on relatively high compression engines where too much advance induces pinking fairly easily. On low compression engines like untuned side valves, current standard fuels are such high octane that too much advance just slows things down and heats things up - at least it does so on my Ariel VB 600cc side valver and my 1935 Oxford. Even my standard Traveller will tolerant a bit too much advance that reduces performance with only roughness rather than pinking.
Regards, MikeN.

[mike.perry]

I agree with Mikes comments. The low compression of the side valve engine will tolerate any grade of petrol and a wide range of timing. The best method is to follow the w/s manual, first checking for any slop in the distributor shaft as in an earlier topic. If the engine is in good condition and you have the patience to get the timing spot on then it should pull enthusiastically up your test hill which sounds very similar to my test hill.

[MikeNash]

Alan,
I'd recommend you set up the timing with a strobe light. (I'm unfamiliar with MMs - I suppose it can be done.) On my Trav its the best way of overcoming slop in the works and the floppiness of a v old chain drive to the camshaft.
MikeN.

[mike.perry]

The slop in the distributor comes from wear in the drive dog pins and in the slots in the jack shaft. If you take out the dizzy and the jack shaft and fit them together they should be a good fit. If you can fit the dizzy 180deg. out then there is excessive wear!!!!!

[alanworland]

I think you would be hard pushed using a timing light on an MM - there is just not enough room to see - in fact the only way I can see the timing marks (at all) is by looking through the radiator fins!
Any advance from TDC (atatic) will produce a deterioration in performance, which is strange because when I dug the manual out again I found that it mentioned advancing the timing as discussed (don't remember reading that before!) I can only assume that it will pink with poor petrol - 'pool' or the old 2 star?
I don't think the drive is particularly worn as the setting is very repeatable with the engine being turned by hand the point will open exactly on the mark.
As an aside I carried the Sat Nav with me to check the speedo readings as the needle seems to have stopped its swinging around, which I found quite accurate - 40 was reading about 41, 50 was reading about 52 and 60 (yes 60!) was about 63 still with some to spare! (dread to think what the piston speed is!)

[mike.perry]

They obviously did not think about the engine being fitted with a water pump when they positioned the timing arrow on the timing cover. The most accurate way of setting TDC would be to set No 1 piston at TDC with the head off, replace the head and dizzy then set the dizzy with a test light and mark TDC on the base of the dizzy and the top of the head as a reference which you can come back to. Or alternatively take the radiator out and set the engine on TDC. I think that I will use the 2nd method when I refit my engine.
I would have thought that it was possible to get some advance on the timing with 95 octane compared with 80 ish octane available when the car was designed.
Another point I have come across on the later cylinder head when trying to set fastest tickover is that with the engine running as soon as you slacken the cotter clamp the dizzy starts to rise out of the head and if you don't hold it down it will lift clear of the drive and the timing will be lost!
It is worth giving the rotor arm a twist to see how much free play there is before the springs take effect.