Lucas distributor advance curves

[100SRV]

Hello,
I have a table showing the different Lucas distributor part numbers applicable to Rover V8 variants, one of the columns has alphanumerics for the advance curve e.g. "F" or "7"

I've had a quick search on the internet expecting to find a Lucas standard detailing advance curves against each letter but no luck so far, have any of you ever seen such data?

Reason for asking:
I have a 35D8 with Lumenition, the engine pulls well but does seem prone to pinking (timing at 3* BTDC at idle) the mech advance is 12* (i.e. 24* maximum)...I also have a 35DE8 (integral amplifier) which would have been fitted to an EFi engine; this has mech advance limited to 6* but I can't transplant the important bits to my 35D8 because that used to have points so the top end is different.

[100SRV]

Bobby Shaftoe said:

It seems odd that the engine is pinking with only 3 degrees at idle and 27 total advance, that's not a lot at all! What's the engine spec and what car is it in?

Have you checked for a) a lean fuelling issue or 2) weak mech advance springs causing the dizzy to hit 27degrees advance far too soon in the rev range?

Hi,
I am wondering about the advance springs too hence my recent dismantling of the 35DE8 distributor (was planning to swap the springs but wanted to compare advance curves first).

It is a 3.9 with 9.35:1 CR using 14CUX injection engine is in a 100" Bowler.

[Steve_D]

Always a good read here.
http://www.g33.co.uk/ignition_system.htm

Steve

[100SRV]

Bobby Shaftoe said:

If i were you, i'd use the piston stop method to verify the damper timing marks and the pointer are in the correct position and you do actually have the advance you think you have.

I'd than grab a dial back timing light, disconnect the vac advance and then record your timing figures at say 500rpm intervals.

Hi Bobby,
those two jobs are next on my to do list.

[Pumaracing]

100SRV said:

I have a 35D8 with Lumenition, the engine pulls well but does seem prone to pinking (timing at 3* BTDC at idle) the mech advance is 12* (i.e. 24* maximum)

Both the idle setting in particular but also the total advance seem far too low to cause pinking. I would have thought 10 degrees at idle and 30 or so total ought to be quite reasonable for such an engine.

[100SRV]

Hi Puma,
there is a definite "rattle" noise and I do wonder whether it is the fuel injectors I can hear rather than pinking, the noise becomes more pronounced at wide throttle openings when pulling hard. Perhaps I need a more skilled pair of ears to listen!

[Lesliehedley]

If you have a leak between an exhaust manifold and the head you get a noise that sounds a lot like pinking under load. Just a thought but it might be worth checking.

[100SRV]

Update

I checked the TDC position yesterday by means of removing number 1 spark plug and using a DTI with a long probe.

Actual TDC was 6 degrees later than advertised on the front pulley!

This explains the pinking noise under acceleration; actual ignition advance is around 9 degrees BTDC at idle.

[Georgie58]

Hi, would love a copy of the information on the advance curves for the different Lucas distributors as I have a couple and not sure if they are from carb or EFI engines. Cheers George

[100SRV]

Hello,
PM me if you want copies of the information I have concerning tuning Lucas distributors.
I checked and I have copies on my PC.
100SRV