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Avery Wise
New User
Username: hans3

Post Number: 15
Registered: 08-2017
Posted on Tuesday, 02 July, 2019 - 20:32:   Edit PostDelete PostView Post/Check IP

Does the Opus sytem have an integral mechanism to cut ignition at redline? I was exercising the 76 Corniche recently and experienced bogging or cutting-out right after the floor kickdown was engaged at highway speeds ~100 km/h. I was probably close to redline but without a tach could not confirm. On one occasion there was a backfire upon lifting off throttle. At no time did the car stall, but it took several seconds for the bogging to clear. Thanks for thoughts.
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Brian Vogel
Grand Master
Username: guyslp

Post Number: 2875
Registered: 06-2009
Posted on Wednesday, 03 July, 2019 - 02:44:   Edit PostDelete PostView Post/Check IP

Avery,

To my knowledge, no.

And what you describe, including the backfire, is precisely what I had happen when my Lucas Opus distributor was days from biting the dust entirely.

One can buy either replacement distributor electronics (Pertronix is one often used) or I've actually found, though not used, instructions for rebuilding the electronics in an Opus distributor: Repairing and Modifying the Lucas Opus Ignition 35DE8 Module

You do not want to find yourself in the same situation I was in when I started the following topic: A Christmas FTP!! . . .

Brian
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Mark Aldridge
Frequent User
Username: mark_aldridge

Post Number: 618
Registered: 10-2008
Posted on Wednesday, 03 July, 2019 - 03:48:   Edit PostDelete PostView Post/Check IP

Avery, check that you do not have a broken wire on the OPUS unit,where they enter the sealant on the unit. The continual movement of the advance retard unit causes the wire to fracture and become intermittent.
Mark
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Martin Taylor
Experienced User
Username: martin_taylor

Post Number: 150
Registered: 07-2013
Posted on Friday, 05 July, 2019 - 17:09:   Edit PostDelete PostView Post/Check IP

Much more likely you only have one fuel pump running and your carbs emptied out under the load
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Brian Vogel
Grand Master
Username: guyslp

Post Number: 2879
Registered: 06-2009
Posted on Saturday, 06 July, 2019 - 00:00:   Edit PostDelete PostView Post/Check IP

Backfires are extremely rare if fuel starvation is the issue.

SRH33576, unbeknownst to me, was running on one side of the dual pump for over 3 years when I acquired her. The discovery of that fact was entirely accidental, and probably never would have happened if a completely unrelated issue had not occurred, but where I suspected the possibility of fuel starvation.

Brian
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Avery Wise
New User
Username: hans3

Post Number: 16
Registered: 08-2017
Posted on Tuesday, 13 August, 2019 - 05:30:   Edit PostDelete PostView Post/Check IP

Attempted to post an update yesterday but it didn't go through. On my next outing the car FTP'd upon exiting the garage. Timing light revealed no current through sparkplug wires on cranking with current (very rapid flashing) only though the coil-dist cap wire. Giggling the wires to the black capacitor within the Opus unit somehow allowed the car to start again. During road test there was no cutting-out at high rpm or backfiring. Thanks for all replies thus far.
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Jim Walters
Frequent User
Username: jim_walters

Post Number: 264
Registered: 01-2014
Posted on Tuesday, 13 August, 2019 - 06:09:   Edit PostDelete PostView Post/Check IP

If you have no spark at plugs but spark at the coil to cap lead then your rotor is failing. Flashing of the coil to cap lead indicates the OPUS is switching the coil to fire. Replace your rotor or at least carry a spare to replace if it quits on you again. I'n not saying the OPUS module wasn't at fault, but the flashing you describe by using your timing light is the classic rotor failure scenario.

SRH8505 SRC18015 SRE22493 NAC-05370
www.bristolmotors.com
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Alan Dibley
Frequent User
Username: alsdibley

Post Number: 204
Registered: 10-2009
Posted on Tuesday, 13 August, 2019 - 17:31:   Edit PostDelete PostView Post/Check IP

Quote: - "but the flashing you describe by using your timing light is the classic rotor failure scenario. " - often caused by people who still will insist on checking ignition faults by having plug leads disconnected while the engine is running. The spark energy must go somewhere, so it tracks across or inside somewhere that it should not, and burns a track through the insulation. It could have been started down the failure path several owners ago.

Sorry to repeat one of the bees in my bonnet.

Alan D.
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Jim Walters
Frequent User
Username: jim_walters

Post Number: 265
Registered: 01-2014
Posted on Wednesday, 14 August, 2019 - 02:27:   Edit PostDelete PostView Post/Check IP

As Alan says the spark energy has to go somewhere. Spark plug leads should never be pulled off a running engine to check for spark. Use a timing light or a spark tester tool.

SRH8505 SRC18015 SRE22493 NAC-05370
www.bristolmotors.com

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