Boss Kettering's Revenge
Here are some posts on the subject from the TR7/TR8 mailing list:
From: Carl M.
I took the back off of my Lucas CEI amp so that I could paint it and noticed the same kind of Delco ignition amplifier that I've seen in GM HEI setups. I also noticed the same kind of amplifier on the Delco amp/coil.
So after examining both more closely, it seems that they are identical, with the exception of an unknown device tied into the - side of the coil output on the CEI unit. If it's a diode (it looks like a hockey puck diode, just smaller) then mine must be open. I can't read the number or I would look it up. Otherwise [it] is the same.
I've heard that the module has a GM part number and I have called a local dealer who says it is the same part as on an 85-87 Chevrolet truck.
The following info was taken from a website that gave technical information for Spitfires. The TR7 and Spitfire distributors are largely the same.
Part: CEI ignition box (75-80 only)
Replacement: standard 4-pin GM Ignition Module
Notes: Take the box off the firewall, pull the screws off of the back of the box, pop the panel off, and... there it is, a GM 4-pin ignition module (along with a capacitor and a zener diode).
Switch the wires from the old one to the new one (straight swap, spade connections), apply the conductive goo (usually included) to the back of the new module, and carefully secure the new module.
Further note - watch all the grounds. Particularily be aware that the GM module body grounds to the Lucas box which grounds to the car body.
Also note that if your distributor has a vacuum unit, it is most likely for retarding the timing at idle rather than advancing it when the engine isn't loaded. If the vacuum capsule diaphragm splits, it will cause the engine to idle too fast. If you're trying to diagnose a suddenly too-fast idle and find the timing advanced, resetting it without checking the distributor's condition may result in a significant performance loss or overheating due to retarded timing at speed.