9 replies to this topic

[minidave54]

Hi All, I have been trying to check the ignition timing using my strobe light. The vacuum advance hose has been disconnected and blanked.

The strobe leads have been connected one to the engine for an earth and the other to the battery pos lead on the starter motor. Induction lead on No1 plug lead

Revs put up to 1500. But whenever I press the button on the strobe to check my timing the engine revs die and the engine almost stalls.

By releasing the button the engine recovers.

 

Has anybody come across this problem before. Need to get the timing checked

[KernowCooper]

Nope not seen that before ? the pick-up is impulse type so remove the connection off no1 plug and try then you will know which circuit it is, unless your leads are shot and the gun is drawing what little spark you have away but you'd think it would just misfire on cyl 1? Try a new 12v feed point for the timing gun, slave battery?

Edited by KernowCooper, 25 September 2015 - 08:29 PM.

[gazza82]

I had a 1098 that ran on two cylinders .. Not well but it ran! (damaged valves)

[fenghuang]

+1 for Kernow's suggestion.
Does the trigger have the same effect with the clamp not on an HT lead?
Does it happen with the clamp on different HT leads? (You can't easily set the timing this way, but it should help narrow down the problem with the timing light.)

[CityEPete]

That is a good one, well done for finding a new problem!

I wonder if the gun wires are going dead short when you pull the trigger in? If you try feeding the gun with the 12V from a battery charger or a slave battery I wouldn't be surprised if it either blows the fuse in the battery charger or the gun wires just get really hot when using a slave battery but the car then will not faulter as you do it, that would be my guess.

Edited by CityEPete, 26 September 2015 - 07:28 AM.

[CityEPete]

+1 for Kernow's suggestion.
Does the trigger have the same effect with the clamp not on an HT lead?
Does it happen with the clamp on different HT leads? (You can't easily set the timing this way, but it should help narrow down the problem with the timing light.)

My gun will not activate without a pulse coming in so that might not prove much, although if it is shorted out inside then it might get hot if he pulls the trigger in for a while as you say.

[Rob1234mini]

Try a different 12v feed for the light also check for a good earth its sounds like your creating your own circuit which is taking the power from the coil

[monkey]

If it is going full short when the trigger is pulled, it may be easier and safer to test for a short with a multimeter rather than see if it all gets a bit hot

[CityEPete]

If it is going full short when the trigger is pulled, it may be easier and safer to test for a short with a multimeter rather than see if it all gets a bit hot

As there is supposed to be a circuit across red and black anyway and possibly only when a trigger pulse is being induced it's not going to be easy to test that way imo, if you use a battery charger as I said before it will pop the output fuse, if it does it's new strobe time.

[minidave54]

Thanks for all the replies.

 

Connected up the timing gun with the induction lead to the No1 plug disconnected, and when operated it made no difference to the engine revs.

Then used Kernow's suggestion and used a spare battery for the power and earth, and all worked fine.

 

Still don't know what caused the initial problem, but I have managed to check my timing.

When time allows I will do some further investigation and try and find the cause of the problem.