Old car, weak ignition spark.

[Chris Moller]

I have a 1972 Mercedes 280SEL 4.5 that, until recently, was running fine, but a couple of months ago it started chugging a lot and it felt like some of the cylinders weren’t firing. I just used a spark-measuring gadget and found out that at the spark-plug end of the ignition cables I’m getting only about 6kv of spark rather than the 20kv or so I think I’m supposed to get.

I just looked at a similar thread on this site concerning weak spark and the suggestions were a weak coil and/or old cables, but I replaced the coil and the cables, and the ballast resistor, two or three years ago. Are there any other possibilities? The car is almost 50 years old–could it be distributor points? Or anything else about the distributor? Anything else come to anyone’s mind?

Thanks.

Topic

[Richard Kirshy]

Hmmm… going deep into old school.
Points, condenser and or rotor / cap may be a cause.

[Chris Moller]

Thanks for the reply.

If there’s a condenser in this beast, it’s not in the distributor, so I suspect it doesn’t have one, and if I’m going to go to the effort of replacing the points, cap and rotor, I might as well stick a Pertronix ignition in it.

[Richard Kirshy]

https://www.pelicanparts.com/catalog/SuperCat/W108/MBZ_W108_ELIGNT_pg2.htm
Mercedes-Benz Ignition Condenser – Bosch 02006
Quantity in Stock: 30
Time to Ship: Ships Tomorrow!
Weight: 0.06 lbs.
Warranty Info: 2 Years
Application Notes:

250S Sedan (1966-67) | 250SE Convertible (1966-67) Coupe
250SE Coupe (1966-67) Coupe | 280S and 280SEL Sedan (1968-71)
280SE All (1968-70) Coupe, through engine # 012487 and with a Cast Iron Distributor Housing. Manual Transmission;<br>Coupe, through engine # 026281 and with a Cast Iron Distributor Housing. Automatic Transmission | 280SE Sedan (1971-72) through engine # 012487 and with a Cast Iron Distributor Housing. Manual Transmission;<br>through engine # 026281 and with a Cast Iron Distributor Housing. Automatic Transmission
300SEL Sedan (1968-69).
Restrictions: Electrical items are non-returnable except for an approved warranty replacement.
Brand: Bosch

[Chris Moller]

Thanks, missed that…

[Billy]

Pertronix beats the hell out of points.

[Chris Moller]

Yeah, I went back and forth a few times, whether to spend the bucks on a Pertronix, but I figured, after almost half a century driving the car, it would be worth it.

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