Timing Light puzzle

[twincamman]

remove the plug lead for number one with the motor at tdc and put a put a plug in the lead ground the plug on the block and slowly rotate the distributor with the ignition on until it sparks --then do it again at 26 degrees advance ---that will tell if all is well electrically-and your timing is set very close ------- -ed

[Hamish Coutts]

Bob,

I take it that the full rebuild included a rebore and new pistons?

If so, I had the same problem years ago with an autocross mini. I spent ages trying to get it to start after a rebore without success. I must have checked the wiring/timing dozens of times.

Then an engineer pal suggested putting a little oil down the plugholes to get a better seal with the new rings and squirting a little petrol down the carbs with a syringe. Damned thing started after a few seconds churning!

Hamish.

[bobashton]

Dear all,

Thanks for the various replies, I have been working away for a few days and had no internet access, I have returned for the weekend ready to rejoin the battle. The support from this forum is far better than the Samaritans!

I'll try and deal with the issues as they have arisen:

I agree with the view that the inductive timing light is probably just compounding the confusion as opposed to diagnosing a fault. I am satisfied that the light works correctly as demonstrated with the Lotus leads connected and running to another engine. IIRC when I fitted the electronic ignition last year I used the light to set the system up then and fitted the leads at the same time. The light certainly worked and the ignition ran flawlessly thereafter. Therefore, for reasons I cannot explain, (I'm useless at electrics) I suspect if I got the motor to run the lamp would operate (just a hunch). The spark generated at the plug when grounded on the block is very healthy and will jump over an inch. The plugs are BP6ES's (non resistor type) and had run beautifully, I cannot imagine they would all totally refuse to fire....would they?

On the subject of ignition leads, I will be checking them again tomorrow as part of my routine and I hope I don't regret this statement, but I am confident they are in the right positions. The Magnecor leads are clearly labelled at each end and I did not detach any from the dizzy cap when I started the strip-down. I swapped the rotor and cap on Tuesday night and checked the order again when I refitted them. However at the stage I am at I am beginning to doubt everything so I will heed Martin's advice and check again.
Thanks for the tip from twincamman, this is something I have not tried up to now but it does sound like a very useful idea. The other methods suggested of adjusting the timing either side of the setting whilst turning over the engine has produced the usual results to date but I will persist. A point that Alaric raised has made me think again about the grounding issue that others have also raised, so I will check the spark plug whilst grounded against its own thread tomorrow as well.
I note with interest Hamish's tip about putting oil in freshly ground bores. Mine only required honing with the pistons and rings remaining, however I did find a similar string in these archives where some guy across the pond tipped a teaspoon of engine oil into each bore, the thing magically sprang into life. Needless to say, this did not work for me. I have also tried the petrol in the chokes thing but then I took off the webers and cleaned everything and all four pump jets have a healthy delivery and I currently spend lots of time in the kitchen flame grilling them dry!
Once again, a big thanks to all for your suggestions, they have managed to keep me going whilst in the depths of despair. My short break away and your ideas have renewed my appetite. I will let you know how I get on.

Regards,

Bob

[rgh0]

Bob

It is possible for the plugs to fire out of the engine but not when installed.

If the rotor or distributor cap or coil is marginal you may be getting breakdown inside the distributor or coil if the plugs in the engine require a slightly higher voltage to fire than when removed.

I would swap out the whole distributor and coil and try spare ones if you have access to spares. If not at least change the rotor and cap and coil.

regards
Rohan