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MG MGA - Pertronix Timing

As the list is too quiet can I ask are there any issues with using the bulb method to set static timing with the pertronix electronic disi set up? I can work out where to fit it but can you damage the unit?

Paul
Paul Dean

Hi Paul
I'm not certain if the Pertronix disi will like you connecting it to a bulb to test it and I wouldnt risk it without checking with Pertronix first,

Electronic disi's are notoriously sensitive to short circuits, incorrect polarity and to input voltage.

(I burned out 2 Pertronix disi's in a 6 month period because, unknown to me, my faulty alternator was putting out over 20 volts!

It proved to be an expensive mistake.

I recall seeing a post on this subject on the US forum written by Jeff Schlemmer, a US ignition expert. These are his words.

"Line up your timing marks to 10 BTDC on the firing stroke.
Pull the #1 plug and ground it to the engine (plugged into its wire).
Turn the distributor CCW much further than you think it needs to be.
Turn on the key.
Promtly turn the distributor CW until the plug sparks.
Now hook up the timing light and actually set the timing once you start the engine. Static timing is just to get you running, NOT for setting the timing permanently. It gets you in the ballpark so you can set it far more accuratley. With a Chinese Pertronix disitrbutor you'll probably find a variance of 4-10 degrees between the dynamic and the static numbers."

This is the link to the forum pages

https://www.mgexp.com/phorum/read.php?1,1764246

Hope that helps
Cheers
Colyn
Colyn Firth

Hi Paul

Don't apologise, I hate it that this forum is so quiet these days.

I had an email from Marvin Grebow at Petronix back in 2010 to say it was not a problem, but as I would hate to be responsible for an expensive mistake, best you double check with Petronix. Especially as I may have a different unit from you (as he needed to know what unit I had before he gave his advice) His email address is (or was) marving@petronix.com. He was very helpful.

But in summary, the instruction he gave with an installed unit were very simple:
1. Connect the clip end of your test light directly to the battery negative or on the ignition wire (Paul -PLEASE NOTE I HAVE POSITIVE EARTH)
2. Place other end of test light on coil negative
3. Proceed with normal static timing procedure.

In the end, I bought a timing light and did it with that

Hope that helps

Graham

Graham V

Have done many times without problems
Dominic Clancy

The reason I asked was that the I had to refit my distributor but I chickened when it came to using the lamp with my newish Pertronix unit to give me the initial setting so I wondered. As I know the normal static setting if I start with the static method I can then clamp the distributor and then use my lamp, yes I have one, and finish of just using the vernier adjuster. This time I did all with the lamp. I will now do as Graham suggests and lamp connections with the guy at Pertronix.

Paul
Paul Dean

Re Paul's opening comment perhaps the Webmaster should extend the date the threads disappear off into the archives. They spend barely a month on the main BBS page.

Steve
Steve Gyles

Having an issue that the 2 timing lights I had access to seemed to disagree I took bull by horns hearing what Dominic and Graham said. I put lamp across my coil and using starting handle had the static reading in about 10 mins. I then used it to calibrate disi vernier and adjusted it to where I wanted it. By the way having a solid precise static reading allowed me to know which timing light to believe.

Many thanks to all.

Yes I have starting handle dog on my early B engine.

Paul
Paul Dean

Pleased you sorted it.
Not sure if anyone has tried this other simple way I have heard about?
Assume you have the engine running, take it for a test drive and see if it pinks under load. If it doesn't, advance the ignition. And keep advancing it until it does pink. Then retard it slightly so that the pinking stops.
Graham V

This thread was discussed between 01/10/2018 and 12/10/2018

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