Th original BAE manual details a modification for the distributor that locks out about 5 degrees of mechanical advance. I haven't done it because I feel it is beyond my capabilities. I don't have a distributor advance machine so it would be difficult to measure and make sure I got it right. one of these days i will probably send it out and have it modified by a pro.
I believe Tsuter had it done to his dizzy.
Of course an easier way would be to just set it at zero degrees BTDC instead of 5, but it would prolly idle and run like crap when not on boost.

sammyg2, again.....beautiful words to hear.
My intent with this motor is to constrain myself within the limits of the system with 6 or so # of boost and make that work the best i can.
If that becomes "not enough", it'll be time for a 3.2 or something else to go in.

Playing around today (i bought THE allen wrench), i followed advice and began richening up the A/F a 1/4 turn at a time while it was running.
The richer i made it, the higher the idle climbed.
OK i'm thinking, let me lower idle speed screw a bit.
I backed the idles speed screw off until it was evident that the throttle plate was FULLY closed and the idle speed screw was no longer in control.
Hmmm, lemme check. Nope, nothing holding it from going any further closed, the throttle plate IS fully closed yet the idle is still at 1500 !!!

Am i to assume at this point that my next mission is to locate and correct the vaccuum leak(s) ???
THEN, readjust the A/F mixture and idle speed.

Excellent info sir !!!

PS
The car just became a whole bunch more fun to drive !!!!!

"Nellie, hold onto your hat and paleezz pull your teets back in the car !"

Playing with the a/f mixture is something that you need to be very careful with. A very small turn of that screw makes a large difference and it's easy to get it way out of adjustment.
It is normal for the idle to climb a little when it is richened up, but maybe not as much as you described.

The idle speed adjustment screw isn't a throttle stop, it is a bypass metering screw that lets air go around the throttle plate.
If you have it screwed all the way in and the idle is still too high, check your throttle linkage to make sure it isn't holding the plate open.
If the throttle plate is against the stops isn't held open by the linkage, and the screw is turned in all the way and the idle is still at 1500, I'd say you have a large vacuum leak.

The srew i'm calling idle speed has a locknut on it and actually does contact the throttl arm acting as a "stop".
I did see another screw going sideways into the TB that may be what you're talking about ?

Oh, OK. The one you adjusted is one of those DON'T TOUCH kind of things.
There is a large screw with a spring under it that sticks out the
left side (driver's) of the throttle body, that is the idle speed adjusting screw.
You will need to re-adjust the stop plate screw to factory settings, I don't remember what the factory setting is off the top of my head but it is an important setting. Once you get that set correctly, use the bypass screw to adjust the idle.
One more thing to check, after you get everything set, make sure you are getting full throttle. Lots of times the bushings or linkage gets worn or loose on these cars and the throttle body will only open 3/4 of the way. If that is the case with your car you will get plenty of extra free horsepower by getting rid of the slack and you will owe me a beer ;)

Hi Sammy,


No, that's not true at WOT. It has only an effect at idle and at part throttle. Because of the simple fact that the WOT switch is specifically there to tell the Lambda brain to IGNORE the O2 sensor and go to it's default WOT rich setting. Grounding the O2 sensor at idle and part throttle simulates a lean mixture to the lambda brain and it goes to full rich on the FV (90% duty cycle or so). This is typically way to rich for idle and part throttle and just causes the usual too rich running problems. At WOT the lambda brain defaults to something around 60% duty cycle. That means there's actually still quite a lot of enrichment capability left. By leaving the Lambda brain in closed loop and using the LM-1/LC-1 to 'fool' it to regulate to a desired WOT AFR, as described in some previous posts, you can make use of that capability AND hold the desired WOT AFR.
A quick and dirty way (without AFR control) is to disconnect the WOT switch from the Lambda brain (so it stays in closed loop) and then instead use the WOT switch to ground the O2 sensor. THAT will cause it to go full rich at WOT only, but then you might be too rich before boost comes on and you might have rich bogs when going to WOT from low rpm.
Whenever you disconnect the WOT switch, disconnect it at the switch itself ONLY, not at the Lambda brain. The 15degC switch is wired in parallel to the WOT switch and grounds the WOT-input to the Lambda brain when the engine is cold. This causes the Lambda brain also to go to it's default WOT setting (and ignores the O2 sensor). You want to retain than function.


Regards,
Klaus

I think I have a new hero. Klaus, you are the man. :)

The hobbs swith I have connected closes at 3 psig rising in the intake manifold and grounds the O2 sensor, making it go rich. Based on your explanation that does make it go very rich under boost EXCEPT at full throttle, obviously there are better ways to do it and the LM-1 is going to get me there. Basically the only time I hit boost is under full throttle, so the hobbs switch is useless.
While I am well schooled in the mechanical field, my skills in electronics are limited but I am learning with the help of folks like you.
thanks again.

Going back to the original issue:

If the car runs better with the 02 sensor disconnected, then why not just replace the O2 sensor? They're fairly inexpensive, and they do wear out...

ianc

Mainly due to what i have read where the lambda system is designed to keep the CO around .8% when the cars seem to like 3-3.5%.

The whole reason for disconnecting the O2 sensor (besides those who don't want to fix something that is broken) is to set the mixture the way you want it, instead of the way the O2 sensor wants it.

Some folks like the little bit of extra torque available from a mixture just on the rich side of stroichiometric and are not concerned that much with maximizing economy or minimizing emmisions.
I prefer to have a fully functioning O2 sensor, some others don't.

To add to what sammyg2 said:

Last but not necessarily least, if your car should have a catalytic converter, disconnecting the O2 sensor and running a much richer mixture than stoichiometric will result in the early demise of the cat. The main reason for the implementation of the O2 sensor was to put the air/fuel ratio in a range to make the cat do it's job.

Personally, i've never liked the furry little bastards !

Hi,

just FYI,

One of my engineers collects and races old Ferraries. One of them has dual CIS-Lambda with two O2 sensors (one in each bank).

He reprogrammed two of our LMA-3 Auxboxes to act as 'mappable' Lambda brain in conjunction with 2 LC-1's. The original Lambda brains are not used in this case. The CIS system with that is now programmable with a 16 x 16 desired AFR map based on manifold pressure, intake air temp and RPM. Also has programmable accel enrichment. All done via the frequency valves.
The MAP sensor in the LMA-3 can already handle up to 2 bar of boost.

If there's enough interrest, we can productize something like that as a kit for around $480.- to $500.

Regards,
Klaus

I found this thread because my plans with a late SC motor are to run it in an early car without the lambda system entirely, so I'm looking for a way to control the frquency valve or use another enrichment system to make the engine usable. What would be the simplest way to do this?

Change your Fuel Dist.

VicSmileWavy

Vic writes:

If you do this (change the FD) , you will also need to change the Warm Up Regulator to one from the earlier non-Lambda engines, like the 78-79, otherwise you will lose your acceleration enrichment.

If you go this route, you would also need to double-check that the throttle body used with the Lambda CIS has the proper port to feed the vacuum connection on the earlier WUR. I think this port may be just a straight shot to the intake manifold, but it could be located in a place that gives some transition from partial throttle. I think I have both types of throttle bodies, I could check on this if you decide to go this way.

Klaus, the programmable LMA-3 is something I am interested in but since I just bought a new LM-1, seems like I'm a day late and a dollar short.
Is there anything that can be done with the LM-1 or is it basically no longer needed if I bought the system you decribed?