Welcome to our resource for MG Car Information.
MG TD TF 1500 - Distributor TD
I'm considering rebuilding my distributor with a pertronix or similar. My car is neg. gnd. but I believe I also need the distributor type to get correct Pertronix unit? I don't see any type on my distributor so how do I determine what type I've got? My engine has the early vertical canister type oilfilter.
|Torben. TDs to chassis number 22734 left the factory with Lucas type DKY4A, part no.40162. Later cars had type D2A4, part no. 40368. The details should be stamped on the flat face of the distributor body together with the date of manufacture.|
|From what I understand the important part of knowing which Pertronix to get is wether you have a symmetric or asymmetric cam in the distributer. I have two distributers and each one has a different style cam, but the distributers are the same. The grounding is of course important. + or-.|
I believe and stand to be corrected there is a part of the Pertronix that fits snuggly on the cam. Important to get the right one.
|Torben, I would not rely on the distributor numbers. There probably have been changes made by prior owners to make that information useless. Here is a picture of how to tell what cam you have which is needed for the proper Pertronix ignition along with the grounding polarity. I have colored the slot for the rotor to help identify the type of cam you have.
|See http://www.ttalk.info/Tech/pertronix_igniters.htm for a bit of info on the installation. Bud|
|I love my Petronix, but dont miswire it or it is toast.|
|Tom Maine (TD8105)|
The Pertronix units are basically the same there is a disc shaped magnet that fits over the shaft and it is shaped on the inside to fit one of the configurations that Jim pictured above.
I recently installed a Pertronix in my TD but since then I discovered that some DPO had assembled the weights and springs from various junk yards. In response to one of Ed Wessons threads, John Scragg posted a nice picture of what it is supposed to look look like inside the distributor. When I compared that to mine I realized my parts were off.
I sent the distributor to Jeff at Advanced Distributors for a complete re-build. He knows his stuff and did a fine job.
|Mort 1950 TD1851 Möbius|
|Actually, there are three cams in different TD's and you do need to determine which you have. Shadetree motors(http://shadetreemotors.com/shadeparttd.html) has the picture of the different cams. This is the late Skip Kelsey's web page and I don't know if it is still in business, but the picture of the cams are listed. Just scroll down.|
I have had a petronix in my TD for at least 8 years and just love it. Have not had to set a set of points in so long. (put petronix in the B also). No problems, and easy to install.
PS. I do have a fully setup point plate in my in-car spare parts as a just in case.
|Bruce don't forget that if you ever need to put the points in while on the road you might want to carry the re-wiring instructions.|
|Mort 1950 TD1851 Möbius|
|I'm not in the pertronix camp. Yes, Jeff installs them on quite a few of his rebuilds, but he sayes that the best thing about them is that will mask worn bushes or other distributor problems. A refurbished distributor from Advanced Distributors will have tighter than original tolerances, a more precise stop arm, and properly adjusted advance springs. Reports on increases of horsepower (dyno pulls on the same engine) with pertronix (usually in the two to three horsepower range) are due to being installed in less than optimal distributors. Jeff sees the opposite in his refurbished distributors... i.e. the points out perform the pertronix.|
I've also never ran into a set of points that I couldn't make work with some emery paper and a matchbook cover. I've seen plenty of failed pertronix including the ones that came on the MGB. That set was not properly secured inside the distributor and eventually chaffed through the positive wire... taking out the ignition (white) wire from the ignition switch to the coil, by way of the tachometer, which also allowed all the Lucas smoke to be released from the white wire and inside the tachometer.
|Dave, I'm a Pertronix fan, but you might also want to revisit this glitch - http://www.ttalk.info/Failure.htm Bud|
|Bud, I forgot about that little issue. Thanks for reminding me. Another reason to enjoy my points!|
How did you shave down the bottom of the red rotor?
|Mort 1950 TD1851 Möbius|
|I have to vote Pertronix. Yes, you do need to file the butt of the rotor down. Dave, I bet you couldn't have fixed my points that had the rubbing block break off! Even when the dizzy is in great condition with no wear, points start deteriorating the second the car starts. The electodes burn, the gap changes, etc., etc. If you want someting to fiddle with continually, great. Electronic ignitions are to me also the greatest innovation in small gasoline engines in the last 50 years. I do still carry a spare loaded breaker plate on long trips however!|
|Mort, I just pressed it lightly against the side of a grinding wheel. Bud|
|Most of the people in the Octagon group that I belong to use a Boyer-Bransden ignition unit. It uses the points only as a trigger for the transistor switching device. The unit does not care about the points gap, it also has an ON led which makes timng a doddle.|
If anything goes wrong it only requires two wires to be swapped, to date the only one to go wrong was because the points insulating washer disintegrated.It is also small enough to hide under the flasher relay box.
Ray TF 2884
|Not sure how you can't be a "fan"...have had the same pertronixs in the TD for 8 years...in the B for 14 years...I'm sure points wouldn't last that long...|
Look in the archives under distributer.
somewhere there it says to measure over the
"flats" Symetric and asmetric cams.661"
and highlift cam .640". I have measured my cam
to .641".It looks like the high lift cam in the picture shown above. My distributr is D24A,40368
prod. 1/53, apparently wrong for my engine XPAGTD 2916.but have worked fine for the 12 years i have owned the car.
Thoralf. Norway TD 4490
|Thoralf Sorensen (TD4490)|
This thread was discussed between 06/02/2012 and 09/02/2012
MG TD TF 1500 index
This thread is from the archive. The Live MG TD TF 1500 BBS is active now.