Ignition Timing for 1098cc unleaded

[traveller1]

I think the timing is a bit out on my 1098 unleaded engine 10V (1971 Traveller) - a pit pinky and sooty plugs . I am also thinking of putting in an electronic points device. My book says Static timing should be 3 BTDC and 6 BTDC with strobe at 600rpm. Is it necessary to revise these figures in light of (a) unleaded fuel ( 95octane rather than HC engine recommended 96) and (b) using a lumenition type device. Is there a diagnostic way to check if everything is OK?

[Alec]

Hello Traveller1

it sounds as if you have already found the answer, if it pinks then retard slightly until it stops. The optimum timing is just short of pinking. Check your mixture first, it sounds rich from what you say. A rich mixture requires less advance than a correct or weak mixture. It's personal preference but I feel that electronic ignition is over hyped and not my cup of tea.

Alec

[bmcecosse]

As above - forget about 'static' timing - just retard until no pinking - then set the mixture to give best idle. There may be other problems - such as vacuum advance not working/carb float flooding/choke sticking on? It all needs checking.

[Alec]

Hello BMCE,

with respect, the mixture should be set before the timing is adjusted, particularly in this case as it seems quite far out?

Alec

[bmcecosse]

Important to stop that pinking!

[Alec]

Hello BMCE,

I agree, and weakening the mixture first will give a better result, how long would it take? It may well not pink then anyway, as it will take longer to burn.

Alec

[Neil MG]

Alec, takes a minute and the result is instant. Normally running leaner is hotter and more likely to pink, so if it was me I would retard the ignition straight away too.

[Alec]

Hello Neil,

it's fundemental, particularly as Traveller1 says "and sooty plugs ", which means the mixture is too rich. Adjust the mixture first then the timing. It's not to do with temperature but the burn rate and a rich mixture burns quicker so requires less advance. Weaken the mixture and more advance will be required. If it's done in reverse, i.e adjust the timing then reset the mixture the timing will need re adjusting.

Alec

[traveller1]

Thanks for the discussion. Can see a way forward - but first need to get a new battery, cos engine wont start due to worn out one - see my question under 'Electrical' - anyone know of a good make?

[bmcecosse]

Do them both together - it will take some back and forth trials to get it right anyway. But I would always stop the pinking as a priority. Costco for best battery buy!