Series 3 1500!! The SU SAGA

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Heres an online comparison chart ...

http://www.mintylamb.co.uk/suneedle/

Put the BGB in first and then take a look at a BDH
I understood that not all the steps on the needle actually make a difference .. the first 2 steps are idle, the next step is empty, the next 4 steps are acceleration and cruise, the next 3 steps are empty, the following 5 are top speed ...
The most frustrating thing is that now the Landy is in the local garage .. my drive way seems so empty .. and i have nothing to mess with ..;-)
 
BENT! .. yes the original needle was bent ... slightly curved but enough to cause the issue.
However it was still going to be too rich at idle so we settled for the BBB needle and the Co2 is now fine ... but NOT the HC ...

HC .. this is basically the amount of unburnt fuel and is reliant on engine timing, try as hard as we can, we can't quite get the levels correct ...
Noted that I changed the timing chain and sprockets a year or so back, it's run kinda ok but now having had the engine on proper test equipment it is clear that there is a big loss of power around 1500 to 2000rpm.
This according to my mechanic is likely to be that the sprocket is just a single tooth out of adjustment.

So next job is .. front off the engine ..

oh joy
 
A tooth is a lot, I would be suprised if its that. I'm more inclined to look at the advance and retard curve. You probably have both a mechnical advance (cetrifugal weights) and a vacuum advance or retard. These work together, the mech A/R advances the timing with RPM and the vaccuum either advances this futher or retards it under load depending on the year as there was a change in philosphy when more focus came on emissions. You can't mix and match, if the vaccum advances then the mech should only do some of the advance, if it retards then the mech advances more and the vacuum pulls it back. If you don't already have one a fully electronic set up may fix this.
 
Great news you got the CO2 down,

I would go through the ignition side first now as ^^^^

But progress is good :)

J
 
rob1miles said:
A tooth is a lot, I would be suprised if its that. I'm more inclined to look at the advance and retard curve. You probably have both a mechnical advance (cetrifugal weights) and a vacuum advance or retard. These work together, the mech A/R advances the timing with RPM and the vaccuum either advances this futher or retards it under load depending on the year as there was a change in philosphy when more focus came on emissions. You can't mix and match, if the vaccum advances then the mech should only do some of the advance, if it retards then the mech advances more and the vacuum pulls it back. If you don't already have one a fully electronic set up may fix this.
Click to expand...

Thanks Rob,
Actually I have an electronic distributer from 123Ignition ... so I have i think 12 choices of curve ... good point .. I wonder if he realizes that?
 
rob1miles said:
A tooth is a lot, I would be suprised if its that. I'm more inclined to look at the advance and retard curve. You probably have both a mechnical advance (cetrifugal weights) and a vacuum advance or retard. These work together, the mech A/R advances the timing with RPM and the vaccuum either advances this futher or retards it under load depending on the year as there was a change in philosphy when more focus came on emissions. You can't mix and match, if the vaccum advances then the mech should only do some of the advance, if it retards then the mech advances more and the vacuum pulls it back. If you don't already have one a fully electronic set up may fix this.
Click to expand...

Thanks Rob,
Actually I have an electronic distributer from 123Ignition ... so I have i think 12 choices of curve ... good point .. I wonder if he realizes that?
 
Backtoback said:
I'm still trying to get my 123 ignition setup but not found anyone who knows what the curves should be
Click to expand...
Me too ... i have had mine now since 2016 and in all that time no one has been able to interpret the data given by 123 and say oh yes for a 2.25 you need this curve, it seems the curves do bear a relationship to an MG and we think that 123 just say that its ok for a landrover as the original dizzy was the same type on an MG and on series land rovers. the only guy it seems who really knows about dizzy and Series land rovers is Martin from Distributor Doctors http://www.distributordoctor.com.
I'm sending him my original mechanical dizzy and he will referb it to spec.

What i can say about the 123 is that i'm currently using curve E for no other reason than that was as far as I got when comparing the them and can't be arsed to go any further with all the fat of having to take it out and set the bloody curve .. the bluetooth version it seems saves all that as you can do it on an app ..

Actually she runs fine but theres a big hole in the acceleration around 1500 to 2000, i have thought this could be timing chain stretch, one tooth out of line and an ACR power plus camshaft would actually sort it out .. one day.

I must say that the biggest improvement was with out a doubt getting the ACR SU carb and manifold.

Having said all that i'm very much up for a discussion on the 123 .. it could be we are one curve and a slight timing adjustment away from land rover heaven .. sadly swiss law forbids me going for a stage one head and i'm only allowed to increase my power by 20% .. or there would be a 6 cylinder in there by now ..

Simon up the Alps
 
Simon Perks said:
Me too ... i have had mine now since 2016 and in all that time no one has been able to interpret the data given by 123 and say oh yes for a 2.25 you need this curve, it seems the curves do bear a relationship to an MG and we think that 123 just say that its ok for a landrover as the original dizzy was the same type on an MG and on series land rovers. the only guy it seems who really knows about dizzy and Series land rovers is Martin from Distributor Doctors http://www.distributordoctor.com.
I'm sending him my original mechanical dizzy and he will referb it to spec.

What i can say about the 123 is that i'm currently using curve E for no other reason than that was as far as I got when comparing the them and can't be arsed to go any further with all the fat of having to take it out and set the bloody curve .. the bluetooth version it seems saves all that as you can do it on an app ..

Actually she runs fine but theres a big hole in the acceleration around 1500 to 2000, i have thought this could be timing chain stretch, one tooth out of line and an ACR power plus camshaft would actually sort it out .. one day.

I must say that the biggest improvement was with out a doubt getting the ACR SU carb and manifold.

Having said all that i'm very much up for a discussion on the 123 .. it could be we are one curve and a slight timing adjustment away from land rover heaven .. sadly swiss law forbids me going for a stage one head and i'm only allowed to increase my power by 20% .. or there would be a 6 cylinder in there by now ..

Simon up the Alps
Click to expand...

I've got the USB version so I have to plug my laptop in to program up the curves, i'll email Martin and see if he can help me with the curve data. A rolling road would be a great help, at the moment I change the points on the curve, take it for a drive, come back and repeat but never had enough time to really sort it. Currently it's fine at tickover and 4000rpm but it's not right between that under load.

Stephen
 
OK, it looks like the 123 unit has a vacuum retard. How does it get its vacuum signal? If the idle and top end are right then I would test it when its hot GENTLY accelerate on a long hill mid range and listen for pinking. If its down on power pick a curve with more mid range advance, if its pinking then less. BUT this depends on my understanding off the vacuum and I'm not sure how 123 do that. Can the vacuum retard be adjusted?
 
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rob1miles said:
OK, it looks like the 123 unit has a vacuum retard. How does it get its vacuum signal? If the idle and top end are right then I would test it when its hot GENTLY accelerate on a long hill mid range and listen for pinking. If its down on power pick a curve with more mid range advance, if its pinking then less. BUT this depends on my understanding off the vacuum and I'm not sure how 123 do that. Can the vacuum retard be adjusted?
Click to expand...

Yes I guess on the version Stephen has he can .. on mine the curves are fixed .. it gets it vacuum signal from a pipe to the carb like normal ...

Heres the curve data .. can you make any sense out of it?

curve advance starts [rpm crankshaft] - 1000
max. advance [rpm] - 4500
[degr. crankshaft] - 26
vac. adv. starts [mmHg] - 100
max. vac. adv. [mmHg] - 300
[degr.] - 14
replaces - Lucas
remark - 2000/12,0
 
The short answer is "no". Is the vacuum advancing or retarding? I would expect it to retard to stop pinking at high load in the mid range and so allow more advance earlier, is this correct?
 
You get a greater vacuum at low throttle positions (light loads). When you boot it, the throttle opens to let more air in, and the vacuum drops. So the 'vacuum advance' provides less advance at high loads, but it's still an advance rather than a retard, if that makes sense.

With an ECU, you can map advance on throttle position (effective vacuum) and engine speed. On a clockwork engine, you don't really have the luxury to do it accurately, but the dizzy uses the vacuum (from the carb) and speed (from spinning weights) to approximate something similar.
 
Thank you. I was wrestling with this. I've had vehicles with both a vacuum retard and a vacuum advance. I think the vacuum advance gave better performance but the retard was better for emissions. Are we clear on what the electronic dizzy does with the vacuum?
 
I've got the USB programmable version of the distributor. I had worked out the curve from the official engine data. The curve Simon lists above is almost the same as I had, a member of another forum gave me what he has running on his which I also tried but it didn't make any difference to the running. I've now changed the coil for the Blue Bosch which is recommend and now it's running perfectly. So although I had the curve correct the coil I was using (although only 2 years old) didn't give enough spark when the engine was under load around between around 1500rpm and 2500 rpm.
 
Backtoback said:
I've got the USB programmable version of the distributor. I had worked out the curve from the official engine data. The curve Simon lists above is almost the same as I had, a member of another forum gave me what he has running on his which I also tried but it didn't make any difference to the running. I've now changed the coil for the Blue Bosch which is recommend and now it's running perfectly. So although I had the curve correct the coil I was using (although only 2 years old) didn't give enough spark when the engine was under load around between around 1500rpm and 2500 rpm.
Click to expand...

Oh that sounds interesting, can you give me an idea of the difference in your curve and the part number of the coil please.. thanks
 
Bosch blue coil 0/221/119/027

The rise in advance at 500 RPM keeps the idle RMP very constant
Land Rover curves.jpg
 
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