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MG MGB Technical - Electronic Ignition

More advice requested. My 81 reg mgb is running on points ignition and has been tuned to run well enough and to be compliant with emmissions regulations (by a professional mechanic). I have a lumenition optronic module that came with the car and seems to be in good order. My question is: If I install the electronic ignition will I have to re tune the carburettors? If so, would this be a minor change or a retune from scratch?
I would like to improve performance slightly but am concerned about carb tuning without a pro gas analyser.
Grateful for all assistance, Steve Elster.
SJ Elster

I have always tuned my carbs with nothing more than a gunson plastic balancer.
Its not difficult and most newer mechanics would not know what to do with carbs anyway, everything is electronic ignition these days.
Assuming that the timing is set exactly the same with the same advance curve, and with a module inside the dizzy it should be, all you may get is a fatter spark which is less prone to variation so it should not make any difference to the carb settings really. IMO
Neckieman

I fitted a lumenition complete with the d45 distrubuter that came with it to my 67b and have not touched the carbs. Very pleased with performance
R J Pemberton

I have run my 71 roadsters now for12 years with the electronic ignition from pertronix, it fits in the dizzy so still looks like original.definitely improved performance with no alteration to the carbs.
Trevor Harvey

It would be very unlikely that you would have to adjust the carbs as a result of fitting electronic ignition. Timing yes as some triggers put the firing point in a different place relative to the cam lobe for a given rotation speed.

But given the struggle you had getting your older engine to pass the later emissions limits, and depending on how close it is now to those limits, it may make a difference at the next test. You may like to fit it then get it tested before the next test is due, so you can go back to points if needed.

But in any event if any adjustment is required to carbs at any time after they have been properly set up and balanced, it must be by the same amount in the same direction on both carbs, or you will have to do it from scratch again.
paulh4

No need to adjust carbs. You might find the car runs better when timed again, as the Optronic tends to compensate for a worn distributor spindle.
Allan Reeling

I too went with electronic ignition after my points kept collaping some 15 years and 35 miles ago. I found better performance, smoother idle. I have a Weber DGEV carburetor.

Cheers

Gary
79 MGB
gary hansen

Gary

I think you need to use your car more often ;o)
Dave O'Neill 2

Dave, you are correct. The more I drive it the better it runs. When I finally retire, I will drive it a lot more. I truly believe if don't run these cars often enough you will have many of the problems we see posted here,

Cheers,

Gary
79 MGB
gary hansen

Point missed?
paulh4

Indeed.
Dave O'Neill 2

Or maybe not.
Peter Allen

I have decided to leave well enough alone for the time being. The testing rules are about to change here soon, with cars between 30 and 40 years old requiring a test every 2 years. I will get it through the next test then tune it for driveability rather than emmissions.
As ever, thanks for all contributions.
Steve Elster
SJ Elster

"the Optronic tends to compensate for a worn distributor spindle."

It's better to fix the worn part rather than mask it.
Steven Rechter

This thread was discussed between 26/03/2018 and 18/04/2018

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