Author Topic: 123 Ignition and Distributor Vacuum Issue  (Read 7499 times)

Nicolas Aristodemou

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  • 280SL Auto 1970 W113, 380SL Auto 1982 R107
Re: 123 Ignition and Distributor Vacuum Issue
« Reply #25 on: October 06, 2019, 02:42:58 »
At the moment the car works fine... smooth idle and revs up very well..... I have driven the car since tgus modification for more than 200 miles .... hope speed relay (connected to coil negative together with 123 ignition black wire) will not be affected.
Nicolas Aristodemou
Nicosia - CYPRUS
280SL Auto 1970 US spec (W113), 380SL 1982 R107, Citroen DS23 Pallas 1973, Triumph TR4 1963, Triumph Stag 1973, Mini Cooper S Mk1
1965, Jaguar 3.8 Mk2 1962, VW Beetle 1978 Karman Converible, 1987 Ferrari 328GTS

Nicolas Aristodemou

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  • Cyprus, Lefkosia, NICOSIA
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  • 280SL Auto 1970 W113, 380SL Auto 1982 R107
Re: 123 Ignition and Distributor Vacuum Issue
« Reply #26 on: October 19, 2019, 15:18:50 »
As an update to my previous posts, I have now driven the car over the past month for more than 800 miles (1300km) and it seems to run fine. I have also tried temporarily installing a series resistor of 50 Ohms between the  speed relay (pin 4) and the coil -ve terminal to check operation and the car still runs ok. Maybe I will leave this resistor there permanently to avoid any risk of damaging the speed relay.
Nicolas Aristodemou
Nicosia - CYPRUS
280SL Auto 1970 US spec (W113), 380SL 1982 R107, Citroen DS23 Pallas 1973, Triumph TR4 1963, Triumph Stag 1973, Mini Cooper S Mk1
1965, Jaguar 3.8 Mk2 1962, VW Beetle 1978 Karman Converible, 1987 Ferrari 328GTS

Tyler S

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Re: 123 Ignition and Distributor Vacuum Issue
« Reply #27 on: October 19, 2019, 15:34:47 »
What is the voltage drop across the resistor? In the original setup with the speed relay hooked to coil positive it would have probably been around 8 volts with the ballast resistor while running. You can check with a volt meter between battery positive and the lead going to the speed relay with the ignition switch on. Keep in mind the 123 shuts off the ground path to the coil when it does not have an RPM signal. 
1968 (67) 250sl. 4 speed manual. DB180 Silver
1955 220 Cabriolet A. White Grey
2019 E450 Wagon. Majestic Blue
1936 Ford PU Flathead V8. Creme on tan interior.
1989 Volkswagen T3 Westfailia Campmobile. Dove Grey (blue)

Nicolas Aristodemou

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  • Cyprus, Lefkosia, NICOSIA
  • Posts: 214
  • 280SL Auto 1970 W113, 380SL Auto 1982 R107
Re: 123 Ignition and Distributor Vacuum Issue
« Reply #28 on: October 19, 2019, 16:50:07 »
I will check it out Tyler; I had originally tried a 33Ω resistor and measured about 9V; I think with the 47Ω  resistor I should be somewhere between 7.5 - 8.5V, but I didn't actually measure it since I only used the resistor only to check if the car started and revved up normally, which it did. All the mileage I have done was without ballast resistor.
Nicolas Aristodemou
Nicosia - CYPRUS
280SL Auto 1970 US spec (W113), 380SL 1982 R107, Citroen DS23 Pallas 1973, Triumph TR4 1963, Triumph Stag 1973, Mini Cooper S Mk1
1965, Jaguar 3.8 Mk2 1962, VW Beetle 1978 Karman Converible, 1987 Ferrari 328GTS

Tyler S

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Re: 123 Ignition and Distributor Vacuum Issue
« Reply #29 on: October 19, 2019, 20:53:34 »
Sounds great. You should be just fine then. 👍🏻
1968 (67) 250sl. 4 speed manual. DB180 Silver
1955 220 Cabriolet A. White Grey
2019 E450 Wagon. Majestic Blue
1936 Ford PU Flathead V8. Creme on tan interior.
1989 Volkswagen T3 Westfailia Campmobile. Dove Grey (blue)