does anyone have the "factory" advance curve specs for a MK1 or MK2 Cooper S distributor? (no vacuum advance)

I'd like to know the exact specification of what the mechanical advance degrees will be through the rev range - from no advance, to fully open

were such details ever published? has anyone measured it from a standard dizzy?

Mk 1 S dizzy specs are in most manuals.
numbers checked when decelerating-
taken from p31 of Leyland black book.
40819B- (Mk1 I think)
dizzy rpm degrees
3800 14-16
3500 14-16
2600 11-13
800 5-7
500 3-6
300 0-1.5
225 0

I have the Mk2 and GT ones here as well.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

thanks Kev...

As I understand it, those numbers are added on to the static advance (5 deg standard for an S) so an S at 3800rpm and above would have a total advance of about 20 degrees. Since there is no vacuum advance, that will be the maximum advance...

IF there was a vacuum advance, what would the maximum advance be?

Doc - if it's not too much trouble I'd like to see those, or at least have a reference to where you found the data.

Out of interest the Lucas Australian Vehicle Equipment Specifications catalogues list the following distributor part numbers:

Catalogue 1958-70 : Cooper S 1968-70 - 62941090A
Catalogue 1971-75 : Leyland Cooper Clubman 1971 - 62941090D
Catalogue 1971-75 : Leyland Police Mini 1971 - 62941122B

All those are 29D4's. I assume the last two are meant to be Clubman GT's. I wonder why the different part numbers for them?

BLMCA Service Letter 4/71 about the Police spec Clubman GT's quotes: Standard production AYG0175 (Lucas 62941090), contact points - Lucas No. GL568 with fibre rubbing block.

The English MKII had a 23D4 P/N 40819H and the Oz Cooper S MkII and GT both had 29D4 P/N AYG0175. The curves on these were both the same;-

Distributor RPM

3800 rpm 14 - 16 deg
3500 rpm 14 - 16 deg
2000 rpm 9 - 11 deg
500 rpm 4 - 6 deg
415 rpm 2 - 4 deg
325 rpm 0 - 2 deg
225 rpm - no advance

It is a little interesting if you plot these and the MkI curves on graph paper.

Simon, yes, these characteristics are for the dissy. Any static timing would be added to these figures, however in both cases check if it is engine or dissy degrees. Sounds like you are setting up another curve for the meggajolt in time for Hay, hey?

For Unleaded fuels these are too slow.

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Interesting!
My Mk1 Cooper S would not like to idle at 500rpm, even struggles at 800rpm.
I think My distributor has been reset to give a maximum of 30 degrees at 3500 rpm with 0 at idle.

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1969 Cooper "S"
1967 Mini Deluxe
1973 Clubman Van (the fleet spare)
1978 ex 1275 LS ("Wizard" Eaton Supercharged)
2015 HSV GenF GTS(occasional drive & tow car)
2019 MINI F55 Cooper S

Like GT alluded, multiply the RPM by two as this is distributor RPM, not crankshaft RPM.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Oops! Missed that.

_________________
1969 Cooper "S"
1967 Mini Deluxe
1973 Clubman Van (the fleet spare)
1978 ex 1275 LS ("Wizard" Eaton Supercharged)
2015 HSV GenF GTS(occasional drive & tow car)
2019 MINI F55 Cooper S

kinda - curious to see what the difference is between the megajolt and a standard dizzy, but also wondering if I have way too much advance. I can take those figures and load them into the alternate map in the computer and toggle between the maps with the switch on my dashboard.

My map is basically the one on this screen, no vacuum (full load) is the bottom line, when I'm cruising along the freeway at 100kph with my foot barely touching the accelerator, I'm running 45+ degrees...



A change I made to the map a while ago was to give it a little more (~2 degrees) advance at idle, it made sense in my head to advance the idle to counteract the cam overlap. Did clean up the idle

Ah correct me if im wrong but you'll still have the same amount of total advance, non?

I was always under the assumption the vac advance job was to give you more advance under low load situations, ie: idle, highway cruising for better economy.

Just for reference, I run two different setups in my ute...
I run 5 deg static advance at all times. In summer I run the vac advance directly off the manifold and adjust the idle down to suit. This gives me ~15 deg more advance on idle which helps it keep cooler. In winter I have the vac adv work off the port on the carb (no vac advance at idle) to help it warm up as the manifold vacuum setup takes ages to heat up on a cold night.
With either setup I still have the same total advance.


Also I've heard most engines like ~30-35 deg total advance and too much can actually sap power... no idea how true that is tho. These are just things I've gathered from reading and playing around with my distributor. I will be switching to MJ soon.. sooo sick of messing around with springs and adjusters for the right curve!

Simon, there are 4 good reasons why a Cooper S advance curve won't give the best results in your motor:
1. cam is way different.
2 fuel is way different these days, burns different to leaded super.
3. C/R is higher.
4. head is modified too.

If you think yours is way advanced, check mine-
NO vac advance:
dizzy advance plate 9° (so 18° at crank)
static advance 20°
total advance 38° @ 4000rpm (at crank)
Why so much advance??
1. head shape (bathtubbed- hardly any squish)
2. cam (RE282)


If I reduce advance, I lose HP and torque.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I would have to agree with the doc.

Generally and I do mean Generally, a 1275 in modified form, Higher CR, Over-lap Cams etc need about 28 to 34 degrees (on the crank) TOTAL advance with wide open throttle and again generally you need that all in by somewhere between 2800 and 3500 rpm. The Cooper S dissy won't give you that kinda advance until your up around 7000 rpm.

Add Vacuum Advance and you it may give you another 8 to 15 degrees on part throttle.

Truely to optimise it, dyno would be the why forward although that Ignition System I mentioned in one of our previous PMs is coming closer to reality

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yeah, I wasn't expecting the cooper s map to be anywhere near right for my motor, just trying to broaden my understanding...

Yes, do need to get it on a dyno, haven't had it on one with this ignition. My guru is too busy to give me some time on it



yes, with either setup there you still have the same total advance, because both situations are using the vacuum advance. But if you disconnected the vacuum advance and locked off the vacuum advance plate, then you'd only have the mechanical advance - which would be less total advance than either of your setups



yep, that's what it's for.... lots of advance to make the best of a small amount of fuel. Holden's research (I think for SIDI) found that the engine only needs to produce 8kw to make a Commodore cruise at 100kph, so they cut the fuel to nothing, advance it till it's about to run backwards, then turn it all forward a bit - hello amazing fuel economy, but of course when accelerating it's still a 2 tonne slug

At full throttle you will have no vacuum advance. It is just an economy thing really.
Be aware that if you have a vac advance dizzy and a cam of 270° or more, the vac is doing sfa when you use any throttle at all... you may as well disconnect it.
So says the man that grinds the cams.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

it's interesting to watch the manifold vacuum jump around at idle from the exhaust overlap interfering with the intake stroke