Spark Plugs--Again! - Page 3 - Alfa Romeo Bulletin Board & Forums
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post #31 of 37 (permalink) Old 05-10-2017, 10:09 AM
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Originally Posted by 180OUT View Post
Well, you are doing this all wrong, Gary. Obviously, you have made an error . . . that you have repeated 14 times! //sarc//
At least I'm consistent.

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post #32 of 37 (permalink) Old 05-10-2017, 10:41 AM
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I'd suspect that something internal is wrong with the MSD.
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Jim . . . '72 Super 1300, '70, 1750GTV, 2nd series,
'62, Lancia Flaminia Zagato3c, 2nd series
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post #33 of 37 (permalink) Old 05-10-2017, 12:59 PM
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I believe that MSD stands for "Malevolent Satanic Device." LOL.

However, I remain open minded, and given the carbon buildup on the chambers I've seen, may have to grit my teeth and give it a try. The multiple spark events at low RPM may be an enhancement.


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post #34 of 37 (permalink) Old 05-10-2017, 03:21 PM
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Just remember to make a blood sacrifice immediately after the MSD is installed and you'll most likely be OK. The electrickery spirits can be fickle.
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Jim . . . '72 Super 1300, '70, 1750GTV, 2nd series,
'62, Lancia Flaminia Zagato3c, 2nd series
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post #35 of 37 (permalink) Old 05-10-2017, 04:10 PM
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Quote:
I'd suspect that something internal is wrong with the MSD
Maybe, but hard to prove without buying a new one. I will do other things before I consider that step.
The Bosch "Automotive Electrical/electronic Systems" book has graphs showing loss of available spark voltage with inductive systems and a 4 cylinder engine with a single coil has falling voltage over 6000 rpm and may be insufficient at 9000 rpm. The equivalent rpms for a 6 cylinder engine are 4000 and 6000 and CD ignition can be a big advantage there. Inductive systems make big sparks at low rpm because the dwell time is sufficient to fully charge the coil between sparks. They don't do so well when the dwell time gets down below 2 milliseconds.

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76 Suzuki GT500
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post #36 of 37 (permalink) Old 05-10-2017, 08:00 PM
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Maybe, but hard to prove without buying a new one. I will do other things before I consider that step.
Unless you're running an MSD specific ignition, I was thinking that you could take the MSD out of circuit and just run on the inductive distributor sensor, assuming of course that is what you have . . . The new MSD's now have a self-test light

Jim . . . '72 Super 1300, '70, 1750GTV, 2nd series,
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post #37 of 37 (permalink) Old 05-11-2017, 07:04 AM
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It is easy to run the coil directly from the 123 distributor when I install a ballast resistor. If this gets rid of the misfire then I will install an HEI module and remove the ballast resistor.
I have a similar misfire on my GTV6 with a Crane Hi-6 and my next step on that car will be to run from the stock Bosch ignition module. Both of the misfires were most apparent when the cars were on a dyno. You can hear a lot more when you are stood next to the motor at WOT with the hood open and no road and wind noise.

Ed Prytherch
79 Spider
85 GTV6 3L
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
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