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MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - Pertronix Ring Too Tall

Back in 2010 Bud wrote an article in TTalk (www.ttalk.info/failure.htm) on the damage caused by the pertronix ring forcing the roter up so high that it crushed the carbon contact in the dizzy cap. I'm planning on installing a Pertronix Igniter (as soon as I can figure out if my '53 TD XPAG/TD2/25404 has a summetric, an assymetric or a Hi-Lift dizzy cam shaft) and wonder if I'll still need to shave 0.030" off the bottom of my red rotor. Has anybody had any recent experience?

Thanks.

Jud
J K Chapin

Hope you get an answer because I've been contemplating the same upgrade, but have been reluctant on the symmetric versus asymmetric decision. I've seen the diagram but still not sure, especially in light of the recent condenser thread. I was actually hoping to do the negative ground conversion simultaneously
Jon Levine

Oops! That should be "shave 0.030" off my BLACK rotor?" It's marked Lucas 400051. The rotor is 0.6695" tall. Thanks. Jud
J K Chapin

Jud, IMHO the only rotor that I would consider using today is one of the red ones from Jeff Schlemmer at Advanced Distributors. Bud
Bud Krueger

Hi Jud,
The only way I could get my rotor to work in the Pertronix was to shave some material off the bottom so it would not crush the carbon contact in the cap. I just kept filing until the necessary clearance was achieved.

George
George Raham [TD4224]

Bud, that's what I thought and I'd have sworn I had the red one in the dizzy. Pays to look once in a while. I'll order one from Jeff.

Based on the numerous threads in the archives, the drawings at Fig. C-20 on page C-12 of the WSM and the attached photo, I'm pretty sure that my dizzy cam profile is symmetric although the slot appears to be aligned like the high lift cam. Given that it seems that the same Pertronix fits both the symmetric and the high lift, I guess it does't matter which it is. One of the threads gave flat-to-flat measurements for the different profiles but, without removing the dizzy, I see no way to get a mic on the shaft to measure it.

I'll post a secnd photo after this one tht may be clearer. Please let me know if you agree that this is a symmetric dizzy cam profile.

Thanks.

Jud


J K Chapin

Second photo of dizzy shaft.
Jud


J K Chapin

George. That's what Bud'sTtalk article says you have to do so I guess you still have to do it. Jud
J K Chapin

Jud, based on your second picture, I believe you have an ASSYMETRIC cam. The lobes on the left and right look to be not as high as those on the top and bottom. This is the center cam as shown in the WSM. I had a heck of a time deciding which is which until I colored the notch for the dizzy with red pencil. Take a look.


Jim Merz

Jim,

The position of the cut out does not identify the cam type, if determines the direction of rotation.

The diagram in the WSM shows the symmetric cam as an anticlockwise cam, the other two are clockwise.


John


J Scragg

Is the only difference whether the Pertronix sensor donut fits or not? If that is the case maybe (assuming the donuts are fairly inexpensive) one could just ask for both and use the one that fits.

thoughts?

Jud
J K Chapin

Yes, Jud, it's only for the magnet collar to fit snugly onto the cam. Bud
Bud Krueger

If y ou look on the Moss web-site they give you the diameter of the three different cams. Mic. your cam.

I have a + ground Pertronix in my TF didn't have to file my Red rotor.
David Werblow

I'm with you David. I've had a problem free pertronix on my TF for several years. I do use the red rotor, but had no problem with the brown one a few years ago. It makes no sense to me that one needs to file down the ring sensor if you have a reasonably good dizzy and ordered the correct pertronix.
I too highly recommend the work of Advanced
Distributors. Jeff will install the pertronix for you when he refurbishes your dizzy.



Tom
T Norby

The current Pertronix kit is equipped with a cam lobe triggered sensor and does not use the plastic ring with magnet inserts, the Hall effect sensor reads magnetic field variations due to the contour of the cam. Which type of cam you have does not matter with this set up.

I am not sure whether the LTS version is available in pos ground, I installed it when changing polarity. All in all I now have 10.000 miles with Pertronix in my TF and I am completely satisfied.

regards,


Jan
Jan Emil Kristoffersen

Jan, do I understand correctly that the current Pertronix kit does not use any ring at all on the dizzy cam shaft?

Thanks
Jud
J K Chapin

yes, no ring at all. Bought it via Moss last winter.

regards,

Jan
Jan Emil Kristoffersen

A problem is that the 'no-ring' version must be used with noise-suppressed wiring. Such is not available from our normal sources. There was a thread about this a short while ago. Check the archives. Bud
Bud Krueger

From Pertronix catalog:
Need an LU-146LS

LS stands for 'Lobe Sensor'
It's the footnotes (13,56,57,79) that are the problem. Bud


Bud Krueger

Footnotes:
Note #79 is the killer:
Igniter II applications can not be used with solid core ignition wires.
From Moss:
I occasionally double-check my in-house references for accuracy. Usually it’s just an exercise, but once in a while I find a problem. This morning I double-checked the substitute distributor cap we suggest for the T Series cars in order to use suppressor spark plug wires.



I found the data to be wrong. In fact, we don’t have a distributor cap for the T Series cars that will accept suppressor spark plug wires.

And:
An option is to use suppressor spark plugs instead. The net result is the same.



I asked our Purchasing Department to see if plugs with the thread length and heat range we want for these T Series cars is available with the specific suppressor capability we need.



I just found out today they are available. The wheels are in motion. We will order in these plugs in our next ordering cycle. (I don’t know when that is.) The part numbers are being created. The information that will describe the plugs in the catalog and the web page is being created.



As soon as they have the new plugs in stock, they will show up on our web page within a day or so. They will show up in our next catalog in the next printing.



So, if you want to be first keep an eye on the web page. It shouldn’t be long.

That was in May.
Believe me, I'll be among the first to go to a lobe sensing Pertronix system. Bud


Bud Krueger

Interesting because i just found the LU-146 LSD at Summit for $113.97 (no shipping charge) and on Amazon for about $90 (Prime) so I think I'm going with it. No radio so I don't think I care about suppression. I'll look but I think my Yellow Jacket wires are not solid core so it should work. I'll let you know.

Wonder how you set the timing - hopefully there will be some helpfull instructions.

Jud
J K Chapin

Jud, the issue is that the EMF will interfere with the electronics of the module. It's not an issue of radio interference. I certainly wish you luck. Please keep us informed. I wonder what the suffix "D' signifies? Bud
Bud Krueger

Oooo! Hadn,t thought about the electronics in the thingy itself. Hope it works. Jud
J K Chapin

Jud, hang on a sec. Just had a closer look at the fine print, i.e., the footnotes. It's footnote #79 that puts the fly in the ointment. However, it states that Igniter II applications can not be used with solid core ignition wires. The LU146LS is an Igniter, not an Igniter II. I see no reason why it shouldn't work, based on their catalog. I'll try to call somebody at Pertronix tomorrow and get this straightened out. Bud
Bud Krueger

Bud, thanks. I'm ready to take the plunge as soon as you can confirm that the LU-146-LSP12 can be installed without having to use special plugs or wires. BTW, the "D" was from my faulty memory. LSP12 is the designation that I see in the catelogs with the "P" apparently signifying suitability for positive earth systems.

Jud


J K Chapin

Sorry, Jud, but after 10 minutes worth of listening to hideous music on hold, the rep at Pertronix confirmed that LS modules will run into problems from the EMF of solid wire ignitions.

Perhaps Jan can tell us what sort of wiring he has in his system that allows it to work. Bud
Bud Krueger

Drat! Jan, can you help us? Did you have to use special plugs or a different kind of ignition wires?
Thanks. Jud
J K Chapin

As I said above, I have had a pertronix without trouble for 5 or 6 years. I am at work now. When I get home I will post the specific model number I bought.
My car is postivie ground. I use bumble bee copper strand core ignition wires with Champion plug caps and a standard Lucas dizzy cap. All screw in. Red rotor. I use the standard spark plugs usually recommended for out cars. I have had no trouble whatsoever.

Tom
'54 TF
T Norby

Tom, is yours an LS model? If not, keep an eye on the inside of your distributor cap and the carbon brush.

Jud, there may be work-around. NGK makes a series of resistor plug covers.
http://www.ngksparkplugs.com/docs/Resistor_Covers.pdf They function with solid core wire. Still digging. Bud
Bud Krueger

Hi gents
Referring to my post above Bud...my unit is a LU-146P12. Dist is the 40367B with a High Lift Cam on it.
Bud, I've had the same Lucas cap for a few years. Just looked at it again. Perfect.

So, for what it's worth, this pertronix works great on my TF.

Tom
T Norby

Tom, take good care of that cap. Not all caps are the same. The carbon brushes are of different sizes. All it takes is about .030" to .040" difference in the distance from the rotor location slot to the carbon brush to cause, or eliminate, the problem. Bud
Bud Krueger

Bud
I will. It is a NOS Lucas cap. I will keep it until it falls apart.
Looking at the Pertronix website, I see that there are now 3 series of them. I guess mine is the "old technology".
But, the early one, like mine, is still available.
It works just fine. I am happy to be free from points adjusting.

Tom

T Norby

My spark plug leads are probably installed in the late eighties when the car was restored in ohio. Original dizzy cap with the screw in retainers. SLim straight spark pug connectors. I never gave this a thought before and reslay dont know if they are supressor leads and caps. Will have a look. Could this be a disclaimer from Pertronix as a problem has been reported but infrequently?

regards,

Jan
Jan Emil Kristoffersen

Checked it now. See photos. Seems to be iron core leads, soft and pliable plain rubber plug caps. Lobe sensor Pertronix works like a charm, a least up to my personal rev limit of 5500 rpm - 60 year old XPEG ....

Jan


Jan Emil Kristoffersen

Another


Jan Emil Kristoffersen

Jan, Pertronix indicates that the LS version is quite different from the standard version, and is an IgniterII. Is there any chance that you could get us an image of the inside of your distributor, with the rotor removed? For our distributors (DKY4A or D2A (late TD or TF)) the Pertronix Igniter module is attached to a plate that replaces the original points plate. The Igniter II, i.e., LS version, replaces the points and the plate stays in place. I'll be anxious to see yours. Any chance that you're running resistor spark plugs. Thanks, Bud
Bud Krueger

My car came with Pertronix when I bought it 3500 miles ago, so far without any problems. XPEG engine, D2A distributor, Pertronix LU146P12 on plate that replaces original "points plate", red rotor, Bosch super plus WR 7 DC+ plugs. Uses Hall effect doughnut over the cam lobes. I restrict engine to 3500revs normally, and up to 4000 revs occasionally with a Hi-Gear 5 speed box.
N D Wallace

For information,
The Pertronix site mentions that the Ignitor II requires a 0.6 ohm coil whereas the ignitor requires a 1.5 ohm

John


J Scragg

John, I think you'll find that the LS 146LS, Igniter II specifies a primary resistance of at least .45 ohms. The standard Igniter, LU 146, specifies a primary resistance of at least 3 ohms. Bud
Bud Krueger

Jan, could you pull off your cap and rotor and post a picture of your installed Pertronix? Did it come with installation instructions? If so, can you send a copy to me at jchapin3 at aol dot com? Thanks. Jud
J K Chapin

See http://www.pertronix.com/docs/instruction-sheets/9LU-146LS.pdf for the 9LU-146LS. There is no instruction sheet for an LU-146LS. See http://www.pertronix.com/support/instructions/ . I could be wrong, but the Pertronix folks that I've spoken with over the phone insist that the LS-146SL is an IgniterII. Bud
Bud Krueger

Here is a picture of the inside of my dizzy with the lobe sensor Pertronix. Seems that I have some wear on the Hall sensor.

Apart from that, a clean look under the distributor cap. Less is more!

regards,

Jan


Jan Emil Kristoffersen

Yes, that's an IgniterII where the module directly (physically) replaces the points. There should be no contact between the cam and the module. I'm not certain that the module is designed for that cam profile. But, as Jan says, it works. Bud
Bud Krueger

There is no contact between the Ignitor II and the cam, but a narrow gap is probably important to enhance the signal strength from the cams inherent magnetism.

regards,

Jan
Jan Emil Kristoffersen

Jan, it looks as if the bottom of the rotor has been in contact with the top of the module. I notice that Pertronix sends a new rotor with the 146SL kits. Did you get the new rotor with yours? Are you using any form of EMF suppression? Resistor plugs, resistor plug caps,etc., ? Thanks for the image. Bud
Bud Krueger

No, they did not send me a new rotor. I have no EMF suppression at all. I use a Pertronix coil as well, HT wires have multistrand iron cores. And no issues, this is my fifth season on Pertronix, and second with LS variety. Had to put the old Pertronix on the shelf when I changed my TF to negative ground.



PS: Has anybody out there experienced interference problems with the LS setup? Or just concerns about the producers info?
regards

Jan


Jan Emil Kristoffersen

Now that's a smooth idle. Prosit!
My long-time contact at Pertronix is trying to resolve this for me. Thanks, Jan. Bud
Bud Krueger

I must admit that it was a very smooth single malt (Balvenie triple cask) - but no idle :-)

regards,

Jan
Jan Emil Kristoffersen

Aww! that's cheating. That's quite a 'wee dram' of a great whiskey.

Jan, do you happen to know the model of your distributor? I would expect it to be a D2A 40368A, or a 40367. Bud
Bud Krueger

I can't remember its number at the moment, but I did check it once and concluded that it is the correct dizzy for my car, with engine XPEG 1292

Regards,

Jan
Jan Emil Kristoffersen

Just a note re Bud's post above.

"I found the data to be wrong. In fact, we don’t have a distributor cap for the T Series cars that will accept suppressor spark plug wires."

Not sure if I'm reading this correctly as I'm not clear where the statement comes from, but the fact remains that the original Champion bakelite plug caps & the original Lucas distributor cap CAN be used with modern 7mm suppressed ignition cable, having successfully done so myself. I used magnecores’ Electrosports 70 – Ignition Cable –SS25 – Metallic Inductance EMI Suppressed Conductor – All Silicone Construction. The use of suppressed cable is recommended with an Electronic Ignition such as the EI 123 & it seems the Pertronix as well.

All original Champion bakelite spark plug caps are constructed with a screw that the original copper HT lead screws into. When using the Magnacore cable it is necessary to drill out the screw & the metal spark plug sleeve, along with some of the bakelite as the wall thickness has to be reduced to ensure a snug internal fit of the new brass cable connector. Remove too much & the cap will be loose on the lead & the wall thickness will also be compromised. I purchased brass fittings from the cable supplier for both the distributor & the plug ends, both of which crimp over & into the cable & are invisible once installed.

As my crimping tool wasn’t designed to secure this type of fitting, I cut the leads to the correct length, allowing a little extra for the core to be folded back under the fittings & took them to be crimped at the local auto electrician, as a special tool is required. It is essential to fit the leads into the circular fibre cable manager with the leads cut to the desired length BEFORE crimping on the brass connectors. It's impossible to retro fit it. Don't ask me how I know. By using some thinners the manufacturer’s branding on the Magnacore cables can be removed.

This method enables the use of an original looking ignition system including suppressed plugs, suppressed leads (overkill I know), Champion plug caps, Lucas dizzy cap & connectors, Lucas dizzy converted to the 123 EI & an original looking coil, with all the advantages of a modern suppressed electronic ignition system.

I'm aware we have moved away from Jud's original query but felt it was important to set the record straight on the use of suppressed leads in our cars. Cheers
Peter TD 5801


P Hehir

Peter, the quote is from an email received from a tech specialist at Moss. What sort of fitting is on the end of the cables that allows them to be retained by the screw caps on the distributor cap? Bud
Bud Krueger

Bud I'll take a pic when I'm next at the car but if you contact a supplier of the Magnacore leads in the States they should be able to supply you with the info. The dizzy end has a brass cap just like the original except it also has a sleeve attached which slides over the lead & is then crimped. I bought the leads & the two types of brass crimped fittings from Melbourne as they weren't available here in Sydney. Cheers
Peter TD 5801
P Hehir

This thread was discussed between 02/09/2014 and 11/09/2014

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.