Electronic Ignition

[George Arber]

I am considering fitting a unit known in the UK as ' The Igniter ' which is the same as the ' Petronix ' as sold in the USA. The unit is for positive earth and is suitable for the standard dizzy DKY 4A . I was asked however was the cam asymmetric or symmetric . Can anybody advise me on this ? I guess that it is to do with the dwell angle . Thanks...George TC EXU 7548 Derbyshire , England [Non-text portions of this message have been removed]

[ian thomson]

Hi George. This has to do with the shape of the distributor cam(not the other one). They changed it for some reason, at some point, though I have never really understood the ins and outs of it. Blower, I believe, tells you how to distinguish between the cams (I seem to remember that there are three types altogether) Sorry I can't be more helpful but I expect one of the more technical members will know. My only question is why do it? Is the unit visible? If so I would not fit it on the grounds that the car does not do the mileage, or need the reliability of these units. I like the old fashioned simplicity of the cars and that puts some mods (notice I said some mods for our more purist members) beyond the pale. Just an opinion you understand. Ian Thomson. --- george arber george.arber@virgin.net> wrote:

> > I am considering fitting a unit known in the UK as ' > The Igniter ' which is the same as the ' Petronix ' > as sold in the USA. The unit is for positive earth > and is suitable for the standard dizzy DKY 4A . I > was asked however was the cam asymmetric or > symmetric . Can anybody advise me on this ? I guess > that it is to do with the dwell angle . > > Thanks...George TC EXU 7548 Derbyshire , England > > [Non-text portions of this message have been > removed] > > > > > Yahoo! Groups Links > > > mg-tabc-unsubscribe@yahoogroups.com > > > > > >

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[Clive Sherriff]

See Blowers Workshop Manual Suppeiment 1 Pages 527 and 528 for illustrations Regards Clive --------------------------------------------------------------------------

----- Original Message ----- From: "george arber" george.arber@virgin.net> To: "mg-tabc" mg-tabc@yahoogroups.com> Sent: Friday, February 04, 2005 11:11 AM Subject: [mg-tabc] Electronic Ignition > > I am considering fitting a unit known in the UK as ' The Igniter ' which is the same as the ' Petronix ' as sold in the USA. The unit is for positive earth and is suitable for the standard dizzy DKY 4A . I was asked however was the cam asymmetric or symmetric . Can anybody advise me on this ? I guess that it is to do with the dwell angle . > > Thanks...George TC EXU 7548 Derbyshire , England > > [Non-text portions of this message have been removed] > > > > > Yahoo! Groups Links > > > > > > >

[joecurto@aol.com]

George the asymetric cam looks like 2 opposite lobes are "melted" while the other 2 are crisper looking. The asymetric and symetric cam was used in 40162 A to but not including suffix E dist, while high lift was in 40162 E, there is a good picture in W.E. Blower manual as well as in TD/TF book. given the amount of parts swapping over the years going by the numbers may not be the best way. Joe Curto [Non-text portions of this message have been removed]

[John Seim]

On the last page of the TD-TF Workshop Manual, section C, Ignition Equipment, also found in the Blower's MG Workshop manual (and I suspect in the TC Instruction Manual) is the figure showing the three different distributor cams installed into the distributors for MG TC's through TF's. Symmetric, Asymettric, and High Lift. Symmetric and High Lift use the same Pertronix ignition kit. The difference in the symmetric and High Lift cam is not visually obvious, with the exception of where the notch for the rotor is, in relation to a cam lobe. The distributor action is counter-clockwise. The notch for a symmetric cam is "ahead" of the cam lobe, while the rotor notch in a "High Lift" cam is "after" of the cam lobe. The distributor cam can be viewed with removal of the distributor cap and rotor. John Seim Irvine, CA george arber wrote:

>I am considering fitting a unit known in the UK as ' The Igniter ' which is the same as the ' Petronix ' as sold in the USA. The unit is for positive earth and is suitable for the standard dizzy DKY 4A . I was asked however was the cam asymmetric or symmetric . Can anybody advise me on this ? I guess that it is to do with the dwell angle . > >Thanks...George TC EXU 7548 Derbyshire , England > >[Non-text portions of this message have been removed] > > > > >Yahoo! Groups Links > > > > > > > > > >

[Terry & Lynda-May O'Brien]

The Petronics is a worthwhile modification and is invisable. No more concern about points and condesor . At least for me, discerning the distinction between a symmetric and asymmetric cam was not easy using the renditions from Blower and trying to relate them to the cam in situ. I got it wrong and tried to use a symmetric sleeve on an asmmetric cam. It dosn't work! I finally phoned Moss tech people and got the dimensions for both cams, the asymmetric is a greater diammeter and that is what I had. Pertronics replaced the ruined symmetric cam under warranty. Good people to deal with. Terry in Vancouver george arber wrote:

>I am considering fitting a unit known in the UK as ' The Igniter ' which is the same as the ' Petronix ' as sold in the USA. The unit is for positive earth and is suitable for the standard dizzy DKY 4A . I was asked however was the cam asymmetric or symmetric . Can anybody advise me on this ? I guess that it is to do with the dwell angle . > >Thanks...George TC EXU 7548 Derbyshire , England > >[Non-text portions of this message have been removed] > > > > >Yahoo! Groups Links > > > > > > > > > > >

[George Arber]

Fellow listers, Again thanks for your positive comments re. the Pertronix unit that some of you have installed . I have a query.............The unit that I purchased the other day is marketed as the ' Ignitor ' kit number LU 146 P12 which is I am advised ok for positive earth, and I understand it is the Pertronix unit as sold in the USA . I advised the supplier that the cam in the dizzy is asymmetric . The part number as moulded in the top of the cam ring is LU 142 ( not 146 ) and the recessed cam form looks as if it is of a symmetric form ! The supplier has assured me that the cam ring is ok for both asymmetric and symmetric. However on attempting to install the unit today, I confirmed that the magnetic ring that slips over the cam does not fit onto the cam because in my opinion it is not for an asymmetric cam. I have also determined that dimensionally it cannot fit or locate accurately The reason for this email is that if the unit is indeed the Pertronix under another name could you have a peek into your dizzy's and if you have an asymmetric cam fitted then what is the part number moulded on the top of the cam ring. Perhaps somebody in the UK has installed the Ignitor. Sorry if I am being a bit of a nuisance but I need some ammunition to convince my supplier ! I hope that you can decipher my description. George TC EXU 7548 Derbyshire England [Non-text portions of this message have been removed]

[joecurto@aol.com]

Tell the supplier that the one for the asymetric cam is LU 146MP 12. M is for modified, the piece has machine marks on the reluctor, and the LU 142 will have been machined off the top. Joe Curto [Non-text portions of this message have been removed]

[D&J Edgar]

George, For what it is worth I have a negative ground Pertronix unit (LU-146) in my TC. Distributor has the high lift cam profile and magnet ring marked LU 142 And I just noticed that on Skip Kelsey's web site, that he has a picture of the distributor cam profiles for identification. http://www.shadetreemotors.com/shadeparttd.html Pertronix info is about half way down page. And according to that, you should have (if I read it right) Pertronix kit LU-146MP12 if you have the asymmetric cam, and positive ground. I have run the Pertronix for about 5 years now and it has been absolutely fantastic. Only glitch when I installed was that the cam ring did not let my rotor seat all the way down. I had to shave a tad off the bottom of the rotor so it would bottom out and not hit cap as it spun. David Edgar, TC 5108 El Cajon, California

On 2/10/05 11:13 AM, "george arber" george.arber@virgin.net> wrote: > Fellow listers, > Again thanks for your positive comments re. the Pertronix unit that some of > you have installed . > I have a query.............The unit that I purchased the other day is marketed > as the ' Ignitor ' kit number LU 146 P12 which is I am advised ok for > positive earth, and I understand it is the Pertronix unit as sold in the USA . > I advised the supplier that the cam in the dizzy is asymmetric . > The part number as moulded in the top of the cam ring is LU 142 ( not 146 ) > and the recessed cam form looks as if it is of a symmetric form ! The supplier > has assured me that the cam ring is ok for both asymmetric and symmetric. > However on attempting to install the unit today, I confirmed that the > magnetic ring that slips over the cam does not fit onto the cam because in my > opinion it is not for an asymmetric cam. I have also determined that > dimensionally it cannot fit or locate accurately > > The reason for this email is that if the unit is indeed the Pertronix under > another name could you have a peek into your dizzy's and if you have an > asymmetric cam fitted then what is the part number moulded on the top of the > cam ring. Perhaps somebody in the UK has installed the Ignitor. > > Sorry if I am being a bit of a nuisance but I need some ammunition to convince > my supplier ! > I hope that you can decipher my description. > > George TC EXU 7548 Derbyshire England

[Skip Kelsey]

George; The LU 146P12 is for positive cars only, and is for symetric and high lift cams only. The 142 on the ring means nothing to you.They use the same ring on the 142 series, but cut a different cut out of it for the T series. Cheers: Skip Kelsey........................................................ At 07:13 PM 2/10/2005 +0000, george arber wrote:

>Fellow listers, >Again thanks for your positive comments re. the Pertronix unit that some >of you have installed . >I have a query.............The unit that I purchased the other day is >marketed as the ' Ignitor ' kit number LU 146 P12 which is I am advised >ok for positive earth, and I understand it is the Pertronix unit as sold >in the USA . I advised the supplier that the cam in the dizzy is asymmetric . >The part number as moulded in the top of the cam ring is LU 142 ( not 146 >) and the recessed cam form looks as if it is of a symmetric form ! The >supplier has assured me that the cam ring is ok for both asymmetric and >symmetric. However on attempting to install the unit today, I >confirmed that the magnetic ring that slips over the cam does not fit >onto the cam because in my opinion it is not for an asymmetric cam. I have >also determined that dimensionally it cannot fit or locate accurately > >The reason for this email is that if the unit is indeed the Pertronix >under another name could you have a peek into your dizzy's and if you have >an asymmetric cam fitted then what is the part number moulded on the top >of the cam ring. Perhaps somebody in the UK has installed the Ignitor. > >Sorry if I am being a bit of a nuisance but I need some ammunition to >convince my supplier ! >I hope that you can decipher my description. > >George TC EXU 7548 Derbyshire England > > > >[Non-text portions of this message have been removed] > > > > >Yahoo! Groups Links > > > >