Advance Curve info for P5 3 litre Mk3

[Geoff]

Hi,
Does anyone have data for the ignition advance curve for a 3 litre Mk3 auto? I have fitted a 123 Ignition and all is OK as far as starting, running, etc., but we are a bit unsure as to the correct switch setting to use on the 123. Currently I have it set to switch position 1, which gives an advance of 16.5 degrees at 2000 rpm, and a maximum of 27 degrees advance at 3600 rpm. Is this about right, or does anyone have the advance data so I can set it correctly?

To assist, the engine (including carburetter) has had a complete overhaul, so should be almost as new, and I am using 98 octane rated petrol. I am not hearing any pre-ignition or "pinking".

Cheers,
Geoff Rogers.

[Phil Nottingham]

The so called advance curve can only be adjusted by springs/weights in the dizzy Electronic systems can be far more flexible. Never hrad of yours!

Base Ignition advance is set statically at 3º BTDC

Centrifugal Advance is between 10º-14º which begins at 900 rpm and ends at 4200 rpm.(LC engines 22º-26º) Its unlikely yours is LC engine a sthese were for export usually

[Geoff]

Thanks for the reply, Phil.
Yes, the 123Ignition device is an electronic unit, made in Holland for several makes of vehicles. Their details and information on the unit are available on their web page www.123ignition.nl

It replaces the distributor and cap, and still connects to the vaccum advance tube, and has a 16 position rotary switch (small) with which you can set an appropriate advance curve, and the idea is to select one which closely matches that of the vehicle in question. For example, the unit I have is a 123/GB-6-R-V which replaces Lucas distributors for 6 cylinder engines. The idea is to advance the settings on this unit until pinging is just detected, and to then back off one setting.

It can offer (via the switch settings) advance curves from 15 degress advance @ 2000rpm - 27 degrees advance @4200 rpm (first switch position 0) right up to switch position F, which gives 24 degrees advance @ 2000rpm and 36 degrees advance @4500rpm. (all crankshaft related)

I suppose that somewhere in this range the Rover 3 litre Mk3 sits most comfortably. If I know the approximate settings for both 2000rpm and around 4200 -4500rpm, I can set the 123Ignition to closelymatch the engine needs.

My particular engine has engine number 80003531A which identifies it as an 8.75:1 engine, auto, RHD Export model, (which it is!), so we know the compression ratio is 8.75, I just require some figures for the advance curve. Are you indicating that the advance is 10-14 degress at 900 rpm? , and do you have any information what it should be at around 2000 and 4200rpm please

many thanks,
Geoff Rogers.

[enigmas]

Geoff, you've obviously got plenty of money or only want the highest quality equipment. The 123 distributor is a top shelf item (just google it Phil).

Someone may be able to post the curve if they can find it anywhere?... but for an auto you want as much initial timing as it will take...use a vacuum gauge for this reading and then use one of the built in advance curves that runs it just below any pinging.

If you have the old distributor take it to an auto-electrician who still has the equipment (distributor machine) and they can record the details of the advance curve for you and then you can select something similar.

Its one thing to know the advance curve but its another to know the rate of the curve.

[Phil Nottingham]

Begins at 900 and ends at 4200 rpm @ 14º per manual. I does seem low but its clearly the figures.

They were only a compromise though