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MG TD TF 1500 - Timing with Pertronix

What is the experience of the group as to the best way to check/set the timing when a pertronix is installed?
Jim Merz

I did mine with static timing and a voltmeter, the same way I did with points. (Positive ground system)

Had none of the problems some have had.
Don Harmer

Hi Jim, Funny you should ask. I have just passed through the very problem that you are having. If you will quickly go to the very last thread still listed at the bottom of the page and read through it, you will come to the reply from George Butz, which will answer your question. I did what he suggested and it worked great. If you have any problem with it, I shall be happy to help you, as George B. helped me.
George Raham
TD 4224
G. L. Raham

Jim,

Used a timing light with the advance feature. Also positive ground, no problems.

Gene
Gene Gillam

Just did mine and used the old tried and true method with a Timing light and going by the sound of the engine turning the Dist.
TRM Maine

Since I dont have a tming light with the advance feature, I will have to learn how to set it static with a voltmeter (Don?).
George, where do I find the info from George Butz?
Thanks to all for a fast response.
Jim Merz

Jim, Go to the last item on the page titled "Thread Heading" with subject "Pertronix Puzzle" dated May 30. Read through it down to where George Butz explains how he times his Pertronix ignition. I followed his instructions and it worked very well. If you have a problem with the procedure, my e-mail is hhraham@shaw.ca and we can talk more directly with each other. I did not use a timing light but only a test light Are you a pos. or neg. ground?
George Raham
TD 4224
G. L. Raham

George, I still have the positive ground.
Thanks for the info. I'll go look.
Jim Merz

Jim, When I got mine timing set to where the motor smoothed out and the RPM was as high as it would get, I locked the distributor in that position. I hooked up my test light and marked the spot on the pulley. I had previously marked the pulley at 5 & 10 degrees advance of TDC. When I checked with the test light, it came on at 13 degrees BTDC. As mentioned I am neg. grd. and I do not know if pos. grd. would make a difference.I hope this is some help to you. Let me know how it turns out.
GEORGE Raham
TD 4224
G. L. Raham

Jim
I have a pertronix and use the static method with a colour tune which is very easy.
tw hager

I tried the static method, which I had done with points, and the car wouldn't run. Almost seemed to be running backwards. I just use a light bulb with some wires and clips soldered onto it.

So then I did it by ear, to where it ran well until the advance timing light I ordered came in. When I retimed it with that I found that the timing by ear method had been way off. So I set it a little before TDC using the timing light and it has been running great ever since. Better than it ever has, with noticably more power and a smoother idle, even though my distributer bushings are new.

It is interesting that when I was all done, the distributor is turned maybe 10 degrees from where it was with the points, even though I was careful to get the magnet ring properly seated on the lobes and fully pushed down. Be careful not to pinch the wires from the sensor under the distributor cap.

I think it was the best $100 I have spent on the car !
I looke at it as less than the cost of one tune-up if I paid someone else.

regards,
Larry
Larry Ayres

Hi Jim, I am curious to know if you got your problem resolved with the timing of your Pertronic Ignition. If you did, how did you do it, as I would like to know what if any is the difference between the pos. and neg. ground setting method. Hoping to hear from.
George Raham
TD 4224
G. L. Raham

There is no difference in timing for a positive or negative ground Pertronix Ignitor, that I am aware of. You do have to purchase the correct polarity part.

The instructions say to time the car statically, as you normally would. Regardless of polarity, some people find that this works, and others do not. A hypothesis that I have heard on other BBSs is that there is some variation of the magnet positioning on the sleeve that goes onto the distributor cam. Another theory that I have heard is that the hall effect requires motion (not stasis) and that by moving the distributor and leaving the wire on the number one plug off a bit so that you can hear the snap, you can statically time it that way.

Regardless, if the car doesn't start, or runs poorly using the static method, then you can time it dynamically, but to do this the easiest way is to use an advance timing light. If you just want TDC a non-advance timing light might work. It would at least get you in the ball park.

I have also seen that the latest Pertronix ignitors for the TD reorientated the sensor on the plate from the right to the left of the center cam. This allows the wires to be routed in a way that is not prone to getting pinched by the distributor cap, and damaged or severed, as was the case with the earlier ones. If you have the early ones you must be very careful when installing the distributor cap.
Larry Ayres

I have been quite suprised that no one has tumbled to the fact that with a Pertronix system the static timing bulb lights opposite for a positive ground car than it does for a negative ground car. The reason for this is the way Pertronix instructs you to wire their unit in for positive ground. Ignition (switched 12 volts)goes directly to the module, and the coil is connected to chassis. Which is the reverse of the usual point system. Not only that but the module is connected such that the current goes through it in the same way for each polarity. This allows them to use the same module for positive and negative ground. Why they don't put both sets of instructions in the same module puzzles me. But maybe they thought they would have too many modules returned because they were not connected correctly.

For a negative ground car connect the light from the distributor terminal to ground. Rotate the dist. till the light just comes ON.

For a positive ground car connect the light to the two terminals of the coil. Rotate the distributor till the light goes out.

I'll get off my soap box now.

Bob
R. K. (Bob) Jeffers

Bob

Thats exactly what I discovered when I set mine up. Purely by accident I noticed that the test light would stay on for a long duration and would be off for a very short period. Led me to believe that the firing was occuring during the "lights out" period. Just the reverse of what you would normally do. I think your the first I've heard of that confirms my theory. I'm not sure why they list one unit for positive ground and another for negative as the unit I have should work either way by reverseing the wiring.

LaVerne
LaVerne

Bob, so that's why static timing doesn't work for the pos. ground! Now we know. George
George Butz

It will work George. Just set the distributor when the light goes off instead of when it turns on. I then checked with a strobe and it was where it should be when firing.

LaVerne
LaVerne

LaVerne -- I think they just show the different part No's to indicate which instruction sheet is inside. The part No's are LU-146P or N (if memory serves).

There is a company, Automotive Essentials Warehouse in Brewster NY. <www.classicgarage.com> that claims to have a patent on modifying the magnet sleeve to fit the symetric and asymetric cams. I believe the standard Pertronix fits the hi-lift cam.
Cheers,

Bob
R. K. (Bob) Jeffers

LaVerne, I understand- I just meant it wouldn't work doing it like when points open when the light came on. I remember it would barely run, or not at all doing it that way. I'll have to check with the light out of curiosity one of these days to see where I ended up. George
George Butz

If all this is true (and I don't doubt that it is), who can explain the price difference between the positive and negative versions then?
Gene Gillam

Good question Gene. Seems like I had to provide the wire to ground to make it work. I'd have to dig the instructions back out, but the unit is obviously designed for negative ground, but can be made to work positive ground provided you rewire per their instructions. I leaning towards coverting the car to negative ground in order to add a cigarette lighter for a cell phone charger while cruising long distance, so may be redoing it anyway. That's after I get done bolting on the same thing you have in the box Gene.

LaVerne
LaVerne

This thread was discussed between 11/06/2008 and 19/06/2008

MG TD TF 1500 index

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