The Lotus Grand Tourers

Have you tried a plug on the coil ht lead to check spark?

Have you tried a plug on the coil ht lead to check spark?

Yes. Nothing sparking.

Did you try a direct feed to the coil ?

Bash

This gives the voltages you can check. (But I would guess you already have this)

Thanks Alan. I hadn't seen that before. It also answers a regularly asked question about the clearance on the Distributor pick up ( 0.20 - 0.35 mm)

Bash : Not tried a direct feed from Battery yet, but I have seen the Voltage drop is the same at the otter switch feed.

More investigation later.

Have you used proper contact cleaner solvent spray on the ab14 and limiter plug contacts? And squashed the plug terminals for better grip? Earth to coil also?
I reterminated all the coil spades on mine, replacing the +ve side with a ring terminal, properly crimped and bolted to the coil. No soldering. Crimping is more reliable. Used a pro level folding crimper plus heat shrink. Not the commonly available blue pinch terminals.

Lucas diagnostic sheet proved very useful.
Test 4 checks resistance of pick up coil. Found it VERY difficult to get a good reading whilst on the car. Looking for 2.5k ohm. Initially I was getting various reading between 5 and 40 milli ohm. I was also getting very different readings when switching the +ve & -ve leads on the meter.
Removed distributor to check rotor air gap and wiring. Gap spot on at about 0.3 mm.
With the dizzy lightly clamped in the vice and the lead to the AB 14 lightly clamped in a smaller vice ( to keep the croc clips in the spades absolutely still), wriggling the 2 pin connector and pulling etc, I could get the resistance to change significantly, but still no where near the target 2.5k ohm. Cleaned female parts of the connector with solvent, then plugged in and saw 3.18 k ohm for the first time on the meter. 50% higher than target, but at least in the right ball park. Eventually, after resoldering the connector with more contact area, I was able to get a steady 3.14k ohm on the meter, irrespective of how I moved the wires around.

Refitted and engine fired up instantaneously. Happy days.

If it plays silly b****rs again, first check will be the resistance. I've crimped some spades onto wires that can be plugged straight into my multimeter to ensure good connection for this test in future.

Tomorrow's another day though.

Happy days

Hope they continue !!

Award yourself a drink or two. Well done.

Bash

Yep - sounds like you might have got to the bottom of the problem - good one!

Pete

Was just reading back through this thread and came across this from HC180 at the foot of page 1:

I had the same symptoms. It was the connector in the middle of the AB14 to distributor wire (under the carbs/airbox). Pushed the bullet through the rubber housing and managed to re-use. It was hanging on by a wire.

I should have paid more attention back in August 22. Would seem a not uncommon occurrence.

MetBlue wrote: Fri Apr 04, 2025 18:38
I should have paid more attention back in ......

your school report was the same I believe!