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Originally Posted by bracurrie
My 061 works fine. The retardation system is wonky, thus evaluating whether to go with out retardation, fix OE system or go with 123 ignition.
I just had no idea the Service Manual was so wrong. I was thinking that the mechanical advance was limited to ~20 degrees and the retard was good for ~20 degrees. So with an 061 if set at 10 degrees BTDC WO vacuum or 5 degrees ATDC w vacuum at idle then at 2200 RPM before speeds witch turns vacuum off timing ~5-10 BTDC then above 2500 RPM all at once retard of ~20 degrees is removed via two way switch and the result is ~38 BTDC. What I don't understand is where does the extra 8 degrees of advance come come from?
BTW what is the difference between an 061 and an 062 distributor? Service Manual says they are the same, but given other errors I wonder.
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I believe that the 061 and 062 are basically the same and there are differences in how they're made but not how they work.
The mechanical advance portion is 20 degrees - you have that right. The vacuum portion is about 22 degrees and is a fixed amount meaning it can't be changed because it's built into the system.
If you set your idle timing to 3 degrees ATDC, the mechanical advance portion will advance to 17 degrees BTDC and that's it. You can buzz your engine to 6,000 RPM and you will still only get 17 degrees BTDC.
At or around 2,200 - 2,500 RPM, the speed relay will trigger the vacuum switch over valve to close and without a vacuum signal going to the distributor the spring inside the vacuum cell will force the distributor to advance 22 degrees. This movement is very quick and you can hardly feel it while driving. 17 + 22 = 39 and that's about where your full advance timing will be with a functional system set at 3 degrees ATDC.
The speed relay will sense that your engine is below 2,500 and it will send a signal to the switch over valve and it will apply vacuum to your distributor as yo return to idle. You really don't need 38 degrees of advance below 2,200 RPM and that was designed into this system. It turns on and off when you need it.
One of the problems with running ignition timing ATDC is that it will make your engine run hot.They added a 100c switch but I find it's too little too late.
If you have constant vacuum going to your distributor and the vacuum system isn't working, it's not really any kind of system at all. If the switch over isn't working only the mechanical portion will make your distributor advance and that's 20 degrees. Depending on where you set your idle timing, you could have anywhere from 17 - to as much as 30 degrees BTDC at full mechanical advance. If you set your timing to 10 degrees you will get 30 full and - 3 degrees you get 17.
It's unlikely that the work shop manual is wrong.
If your switch gear isn't working you can get a 123 distributor that you can program to mimic the way the 061 works.