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ernzo2 Avatar
ernzo2 Silver Member Ernie Stires
Denver, CO, USA   USA
Yes, I have a 1977 with the opus.

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Steven 67GT Avatar
Steven 67GT Steven Rechter
Imperial Beach, CA, USA   USA
In reply to # 3714881 by ernzo2 Yes, I have a 1977 with the opus.

The Opus is probably the most unreliable electronic ignition ever produced. It's likely the source of your running problems.

You would do well to replace the distributor with a Lucas 25D.



There are no bad days at the beach.



Edited 1 time(s). Last edit at 2018-04-11 12:47 PM by Steven 67GT.

ernzo2 Avatar
ernzo2 Silver Member Ernie Stires
Denver, CO, USA   USA
Ha, yes, my opus actually does work, the issue is intermittent which would be unlikely if my unit was bad. Additionally I bought a known good unit to test and the issue persisted. I have an flamethrower but I cannot really instill it until I can isolate the issue as I will be compounding my unknowns...

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ernzo2 Avatar
ernzo2 Silver Member Ernie Stires
Denver, CO, USA   USA
So replaced plugs, old ones were NGK BPES, they were carbon’d up, but to be expected with the starting issues. Old gap was 35/38...


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daharleydude Avatar
daharleydude Silver Member John K
Ashevillle, NC, USA   USA
About the gas pressure in Webers, I think 1/2 PSI is too low. I am more familiar with the Weber down draft carbs and they say that the optimum pressure is between
1.25 to a maximum of 3 PSI Maybe it is different on side drafts Webers, so check the specs and make sure your gas pressure is within the accepted range. Too much pressure is just as bad as not enough, so this is a critical adjustment.

lewk Avatar
lewk Silver Member Keith Lewis
Cambridge, ON, Canada   CAN
Fuel pressure for Weber is 3 PSI.

ernzo2 Avatar
ernzo2 Silver Member Ernie Stires
Denver, CO, USA   USA
Thanks, I was just guessing at the pressure, the car has the original pump running through a clear filter under the hood. I have a FP testing kit, maybe I’ll dig it out. Thanks for the info.

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ernzo2 Avatar
ernzo2 Silver Member Ernie Stires
Denver, CO, USA   USA
Little update, I did replace the drive resistor and she did fire up perfectly, but as expected, later in the day and the next morning, crank no fire. I will have time tomorrow to spend time again. At least the weather is getting warm!

Steven 67GT Avatar
Steven 67GT Steven Rechter
Imperial Beach, CA, USA   USA
In reply to # 3717200 by ernzo2 I did replace the drive resistor and she did fire up perfectly, but as expected, later in the day and the next morning, crank no fire.

High wattage (drive) resistors do not fail unless whatever is drawing current through it has failed. Trying to get your Opus ignition working is like beating a dead horse and throwing money into the wind.



There are no bad days at the beach.

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ernzo2 Avatar
ernzo2 Silver Member Ernie Stires
Denver, CO, USA   USA
Well, yes perhaps, I do know the fallibility of the 45DE4, initially I had a series of other issues that were perplexing, so while I have exchanged my old questionable 45DE4 for a know good,I do remain skeptical. Thanks, I appreciate your advise!

Wachtmans Avatar
Wachtmans Wouter Strodijk
OVERVEEN, Noord Holland, Netherlands   NLD
1974 MG MGB "The Bee"
1974 MG MGB "The Bee"
1974 MG MGB MkIII "The Bee"
I don't want to suggest I am an expert within this field of knowledgable people, however, I experienced alike problems with another car recently. Lotus Elan with hor. Webers. We found sticking valves in the fuel pump; slimy deposits of old fuel made the pump only work intermittent and pressure too low. The tiny little valves were taken apart and once they were thoroughly cleaned, the problems were gone.

ernzo2 Avatar
ernzo2 Silver Member Ernie Stires
Denver, CO, USA   USA
Hi Netherlands! A good idea, yes. The MGB fuel pump is easy to take off (I did it once to fix a wiring issue)

intermittent issues are so difficult to trace...

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