Thread: Lucas ignition amplifier replacement by Bosch 024

Some observations:

1. I avoid open crimp connectors like the plague. The one you have on the +ve side of the coil needs to be tight to the point of resisting pulling off by hand. Pop a small bit of hose over the exposed terminal to keep it clean.

2. Wrenching off the amp may have opened up the connectors on the dissy. The same thing with tight terminals applies here, make sure the new connectors go in with a little force. You can tighten the sockets through the blue rubber with small pliers.

3. Test the ignition output by setting the star rotor just before the pickup. With the cap off and the ignition on, bump the rotor button so the two points meet and pass. You should get a good spark at the coil out of it. If not, check all the terminals, the earth through the bolts for the coil and amp bracket, check there is a good voltage at the coil +ve. If the rotor-to-pickup gap is too high it will fire the Lucas amp but not the Bosch. They are slightly different.

4. You will probably have to advance the timing somewhat, the voltage generated by the pickup has to be slightly higher to fire the amp, which means retarded timing. With a smaller gap this is less noticeable but still necessary. I don't recall not being able to get to the dissy clamp nut, a decent 9/16 inch spanner should get it.

Thanks for the quick reply Bee Utey.

Replaced the open crimp connectors with o-ring ones - no change to ignition but good to do. Other connections seemed pretty good, including nice and tight going into the blue thing with the cut down spade ends (once working I'll add some silicone over these).

Will open up the dizzy in the morning and check for sparks - haven't done the timing thing before so should be interesting...

The dizzy clamp had me pulling my hair out - could get a 9/16 spanner on but no room to turn it, got a ratchet one on, not enough space to turn for a click, socket could get on but not with a universal joint on the end, didn't want to buy a complete crows foot set so eventually, eventually, gave up!

hi Simon - re trying to loosen dizzy nut, on my disco the top of the radiator shroud unclips and comes off. makes it easier to swing a spanner in there. just a thought - you may have done this already.

I use a socket and a long extension with a ratchet handle for the dizzy clamp and it just does the job. Very strange design. I will probably put in a capscrew one day as getting an Allen key socket in there would be easier.

Originally Posted by pibby

hi Simon - re trying to loosen dizzy nut, on my disco the top of the radiator shroud unclips and comes off. makes it easier to swing a spanner in there. just a thought - you may have done this already.

That rings a bell, I remember poking the spanner's other end into the fan to get the nut to move. Tap the spanner with a hammer or lever it off something else.

The fan belt also seemed to be perfectly aligned to prevent a spanner turning when between the fan blades - might be a different experience for w/o air con.

Will attempt it again this morning with the tips above, maybe cut a spanner down or something too.

Yes an allen key would have no issue, good call if I do get it off...

Is taking the fan belt off an option ?

Mine is the 'Serpentine' belt, easy(ier) to remove I think...
Fan a viscous hub? - turn the blades to find the bigger gap.... Spacing (should be) is uneven to modify fan-noise.

Darkly muttering threats to replace with 'japanese bolts' is counter-productive, but wearing a grey dust-coat over a shirt & tie does the trick for me!.

Allen heads might not work, due to the 60 degree rotational spacing/limited access, whereas the open-ender with its off-set angle gives more 'tiny bites'.

Or use a bigger hammer as suggested...

Spent some of yesterday working through the list:

Checked the connections on all the wires in the amp, coil and into the distributor, all looking pretty clean and tight.

Opened up the distributor, checked visually everything looks how it should, and that it spins when trying to start the engine and hand cranking it.

Adjusted the air gap of the star rotor to 0.10mm (0.004in), tried to slip a 0.25mm (0.010in) gauge between after to double check that my adjusting had actually done something, and there was no way it was going in though it had initially.

I'm a bit of a novice with a multimeter, but with the ignition on, checked for voltage on the + and - points on the coil - both getting a shade under 12V. I used the bolts holding the coil to the body as earth, to ensure the coil was getting a proper earth. Also used another earth line - left over from previous coil install, to go from one of these bolts to the + point on the coil.

Also with ignition on, tried lining up the rotor button just next to the star rotor pickup, and flicking the rotor with the dizzy cap off, and also hand cranking forward and back across this point with the cap on. I couldn't hear anything in the coil, and with the high voltage cable off couldn't see any spark - is there a better way to check the coil during this to see if it's sparking?

Managed to loosen the distributor clamp nut - 9/16 dwarf spanner and a grey lab coat to the rescue. I rotated the dizzy to visually check it, and then statically adjusted the timing. I haven't done this before, but given I hadn't removed it (not really seeing the value in that for solving this issue) hopefully I haven't gone too far wrong. I hand cranked to TDC, rotor was at #1 position, positioned the dizzy body to line up my #1 mark on it, and hand tightened the clamp nut. Then cranked to 6deg BTDC and rotated the body very slightly so my #1 mark was - maybe 2mm - further counter-clockwise from the rotor centre and tightened the clamp bolt further, this was to advance the timing from factory as suggested.

Throughout it all, car turns over when I try to start it but doesn't fire (also checked for petrol and yes, petrol!). Battery starts to tire pretty quickly when trying it, so just charging it up presently. Any leads or tests to run would be much appreciated!

Cheers, Simon.