Transistorized Ignition Bypass

[fmen3366]

My 70 280SL just had an engine rebuilt by Metric. An older MB gentleman from Santa Clara CA familiar with our cars did the installation. He also rebuilt my dizzy. Make a long story short, the car runs fine. I'm very happy with the work he's done. However, I found out that he bypassed the transistorized switch (under the battery) after diagnosing that the ignition was not getting spark from it. He thought he'd save me some major dough by doing this. He saw no reason why his current setup (different coil, etc) wouldn't do the job.

After spending countless hours reading forum postings on everything from dwell settings to going electronic--occasionally drifting into the dark abyss of “white sidewall tires or not”- I’m now questioning if the bypass trick is a good idea (even though the car runs fine).  I’ve asked my mechanic if we can put the original configuration back to run on transistorized setting assuming that I can find a good used one or universal switch that will not tear my arms and legs apart.

Also since I’m thinking of going the Pertronix or Crane route, do I still need the original transistor switch to work with these setups? I read that the Crane has an external switch/control module. Does this module replace the transistor switch? Thanks, folks, in advance of your advice.

Andy

[graphic66]

I remember an earlier post where The Velleman K2543 Electronic Transistor Ignition Kit was recommended as a replacement for the expensive Mercedes switch. It  changes the points from handling high amperage to low amperage, I think exactly what the stock Mercedes system did.
   I bought the kit and just assembled it, a fun soldering project. I am going to put it in my 230SL to experiment and have some fun, even though I am a fan of original points in these cars.
    I just love to build circuit boards and this was a fun and easy project so far. Not sure if this will fit into your original housing under the battery. It should make point changing intervals extend greatly, or as Velleman claims  "It gives your car the feel of an expensive luxury car". Well, I thought my 230SL already felt like that, but I will see.
    Here is a link to the product  http://www.abra-electronics.com/products/catalog/Velleman-K2543-Electronic-Transistor-Ignition-Kit--p-37.html  It is available many places. Here is the manual http://www.velleman.be/downloads/0/illustrated/illustrated_assembly_manual_k2543.pdf  . I will post up my results if I ever get time to put it in.
    If you can't solder circuit boards, don't get this kit. It involves some basic circuit board soldering, very simple, but you need some soldering tools. A soldering gun, some electronic solder, some compatible flux, small wire cutters,  and in my case a big magnifier.  It only took about an hour to assemble. The directions were very simple and the kit is layed out nicely. Velleman also has some nice looking headlight warning devices,  intermittent wiper kits and security systems. Just check before ordering what tools are needed, some kits require a scope or more advanced electronic tools.

[mdsalemi]

Andy,

The purpose of any of these electronic systems--be it Crane, Pertronix, or whatever, is to reduce the amount of current through the points.  Instead, the points are used as a switch to shift the higher current switching to a transistor, if that makes sense.  So, the first step of any electronic ignition is simply to shift high-current switching from the points--mechanical--to a transistor--electronic.

Pertronix and Crane and others employ this but take it a step further by eliminating the points altogether.  Crane employs a large external box (it is a derivative of an older Lucas model) and an optical switch inside the distributor to perform the switching.  Pertronix uses a sensor (Hall effect magnet and pickup, I believe) instead of an optical shutter, and no external box needed.

There are detractors and proponents of both systems.  The newest is the 123 distributor replacement.

They all work well, they all have their issues.  So do points.

Search around this site for various postings and you'll read about various experiences with all systems.

[jeffc280sl]

Hello Andy,

I'm familiar with the Crane ignition system.  It comes with a small box that replaces MB transistor unit.   I mounted it under the battery tray in the same location as the MB original.  The Crane system installation is much easier if you can remove the distributor.  With it out of the car you can set it up on a bench with an old battery to get the optical trigger installation and alignment perfect.

[fmen3366]

Thanks Graphic66, Michael and Jeff for the advice.

I went through tons of discussions on Crane or Pertronix in this forum. Since I have a rebuilt dizzy and not masking any problems, my inclination is to go Pertornix for now.

Andy

[mdsalemi]

Having had points, the Crane, and the Pertronix all in my car at one time, I can tell you with certainty that the Crane is NOT the easier to install, but actually the more difficult.

Ignoring runnability issues (which I don't have but others have had with any system) the Pertronix is the simplest install and setup; points behind that, and the Crane the most difficult.

When all are in and working well, the Crane and the Pertronix should not need any attention for a long time.  Don't hesitate, however, to carry spares with you on a long trip.  It's cheap insurance.  Jim Villers has had, I believe, the Crane box fail on him.  I had some Crane issues too, but never the box.  I carry a spare Pertronix with me as Pertronix is the unit I have now.  It's the same with points--if you are taking a long trip you want some spares with you, like points, rotor, condenser, etc.

This is merely a condensation of a lot of posts on the subject.  Do a little searching before you choose to change from any one system to any other system.