Bosch Blue Coils... for older OPUS systems?

[bmurphy7369]

Has anyone used a Bosch Blue Coil and done away with the ballast resistor on an early OPUS (1975 in my case, XJ6)?

Just wondering if this was a good step to make, especially considering the wiring mess I have run into lately. I assume the internal resistance just does away with the need for running the RUN wiring through the ballast, and nothing else changes? Let me know if there are benefits/drawbacks if you have run into this option.

Brian

 

[PeterC]

A Bosch Red coil uses an external resistor, fwiw.

 

[Exotexs]

Brian, check this site:

https://www.reopus.co.uk/Original%20Wiring%20XJ12.html

 

[bmurphy7369]

Hey guys,
Thanks for the info... the picture for the reOpus showing the ballast/starter relay helps me alot... On my car, this unit is rusted through, hanging off the fender well, and could be a source of the no-start while hot condition I was having. The coil checks fine, but with all of the trial and error I have gone through I doubt it will last. The red coil from bosch sounds like a good idea to me. I wish there was more info out there about the 4.2L OPUS systems. It seems like Jaguar didn't tell anyone they fitted the US Emmissions cars with the OPUS, Haynes even shows their information as part of the Appended information in the XJ6 Repair Manual, which was written well after OPUS was phased out of the line.... I am going to try to contact the ReOpus people about converting back to all OPUS components and hope that their product will work on the 6 Cylinder cars. If not, I will keep with Crane for now, but still no start to date. Thanks for all the help, every piece of info is getting me closer to understanding the complex igniton issues here. This weekend I am planning to jerk it all out and totally clean up every wire, test continuity and re-check plug wire order, etc.... the car will start, just not on my command! I hope it gets over its moodiness soon so I can enjoy some summer days in the country. The next option is the local electrical shop, but they park the cars outside and I can't really pin them down to a day that they can get to it. It can't stand any more rain, until I clear the body drains and get the door mirror back on, RH gas tank capped or removed (one fussy bolt holding it). It may be better to let the pros track it down though, and I can do the major cleanup to the wiring and relays later on to save some money. Thanks again, anyone with a 1975 XJ6 feel free to chime in as well. I hope you're having a better experience with your ignition! I really probably need to study a picture of the ballast coil wires from a 1975 4.2 or see one up close to grasp the mods made to my car and fix them..
Brian