Series 3 Ignition Timing 2.6 Litre Petrol

Recently bought a Series 3 LWB with a 2.6 litre petrol engine. The original workshop manual only lists timing for 90, 85 and 83 octane fuel.

Has anyone got any advice about best timing set up for modern 95 or 99 Octane fuel? And also whether lead additive is a good idea.

Not sure if mine is a 7.8:1 or 7.0:1 compression ratio. (How do I tell?)

I've read lots about timing it by ear, but as a novice I'm not sure what I'm listening for, so would prefer some BTDC / ATDC values.

Took my new toy around the block last week (with very approximate timing, just to make it run). Stalled if I didn't give it any choke. Ran rather hot. Left a trail of fuel up the road!

Thanks.

You only need additive if the valve seats haven't been replaced.
The higher the compression, the more you retard, the higher the octane, the more you advance
I don't know the actual values for that engine but I'd start at 3°btdc and take it from there especially as you don't know the compression though I'm sure it's on the engine somewhere

By ear.. get the engine hot and advance timing until it starts sounding rough or uneven, then back it off again until it sounds nice, smooth and regular. Go for a drive, change gear early to load the engine and listen for knocks/rattles. If you get some then back of the timing a bit more and try again.
To much advance and you get engine knock/pinking.. to much retard and you lose power.. you want the sweet spot between the 2

With respect to engine heat.. i remember the 2.6 known for it. Check the radiator is good and has good flow. Check the carb isn't set to lean

By ear is a thing that takes time to tune in the ear .

Do you have any basic tools?
For this I mean a timing lamp.
Get it up to temp on the drive and slowly turn the distributor till it don’t sound good, turn it back a smidge.
You will get to know the pinking sound (it’s a bit like a petrol engine sounding like a diesel)
Best found under load foot to the floor On the go pedal.
Kermit already said most of that.

You need to check the vac advance on the distributor and the pipe to it as well .

But needing choke and running hot I would say then a very good services of fluids and filters plugs, points would be first, then see what you have, getting hot for around the block don’t sound good.

where in the country are you based (roughly).

J

marjon said:

But needing choke and running hot..

Click to expand...

Sounds like it's running lean to me

Thank you both for the advice.
Based near High Wycombe / Amersham.
Have a timing light (if it still works).
All very new to this.