Advance curves

[haggis]

Hi folks, can anyone supply me with advance curve data for a vitesse mk2, running Lucas distributor please. And if there is anyone running a 123 tune + dizzy on their late vitesse or Gt6 that might also supply their curve data, that would be greatly appreciated. 
 

thanks

Hag 

[Clive]

Don't have my (proper) work shop manual to hand, but pretty certain it is all in there.

If you don't have a WSM, the vitesseseteve website may well have one for free download.

[Pete Lewis]

blimey Clives up early 

http://vitessesteve.co.uk/

there is dizzy test data in the V mk2 manual 

you should find a note in most test data that is done  decelerating 

contrary to normal thinking 

Pete 

[Colin Lindsay]

Pitch dark this morning, and the clocks went back too, so all of the terrible TV programmes that should have started at 7am didn't really start to 8am....

This any use, Haggis?

http://mgaguru.com/mgtech/ignition/pdf/tuning_lucas_dist.pdf

https://www.sbmsclub.com/wp-content/uploads/2018/03/lucas-dist-chart.pdf

[JohnD]

This is from GT's little book, and as he was usually precise on facts, but liberal in interpretation, I think you can reky on it.

John

[haggis]

Thanks for all your help guys, I’ve set up my 123 dizzy and runs awful, gonna try some tweaking, any idea of vacuum data/curve for a 22D? 
 

thanks

hag 

[JohnD]

Hagggis,

Did you even look at the graph I posted?     Post before yours.  "22D6"

[Pete Lewis]

wsm gives for a lucas 22D6vacuum data 

ins hg 6    4deg @crank max.

8.5  ==  8deg

14 = 17deg

18 = 22deg

20 = 22deg

centrifugal  as decelerating 

300 dizzy revs  1 deg crank

750 = 9  max

1150 =  12

2300 =  19

3200 =  20

Pete

[haggis]

John D, you bet I looked at your curve, good to see some crank advance figures rather than centrifugal, as that’s what the 123 uses, very useful to compare to all other data I’ve gathered. And thanks Pete for the vacuum data, I’ve searched the internet for them, hopefully I can translate them into something I can get the 123 to understand.
It’s all new to me. 

thanks again 

hag 

[Pete Lewis]

dont forget the advance centrifugal is always decelerating  thats how they and we tested dizzy against the specified data

as i said this goes against the expected norm but its the way they do it  ,,,,,,,so take it up to 3000 ish+  and back it off checking as you go 

if you then re plot the curve accelerating you get a very different result and it shows the hysteresis of the climbing and descending variance in the springs and weights 

i dont know why the data was done this way  

[Pete Lewis]

here is some more bumf 

https://www.teglerizer.com/mgstuff/advance_curves.htm

Pete

[NonMember]

1 hour ago, Pete Lewis said:

dont forget the advance centrifugal is always decelerating

How much difference does it make? And which curve should you use for a 123 electronic unit that won't exhibit that hysteresis?

[Pete Lewis]

without doing a test i dont know ,  but its specified as decel so thats what the   WSM  says 

we tested  dizzy's returned under warranty and only matched results with the approved test , 

long time ago now , seem to recall lucas  was definitely decel .........but an american unit as tother way round ( but that was  80's  electronic)

rules of confusious  Ha 

Pete

[NonMember]

My guess would be that the mechanical advance could suffer a bit from stiction. If so, it will tend to be over-advanced on the decel test, which is probably the condition you want to avoid, and are testing for. Ideally there should be not very much difference, and with programmed ignition you can be pretty sure there won't be. So the WSM spec being "test on decel" means it's the maximum safe advance, which is probably what you want for setting up a 123-tune. At a guess, of course. 😉