Converting '71 280 SL to Electronic Ignition

[blairwag]

Well, I guess I'm just the schmuck with endless questions.

In my recent burst of insanity, I've decided to embark on the task of converting my 280 SL to Electronic Ignition. After reading several posts, and the technical artical under Engine | Ignition ( http://www.sl113.org/articles/engine/ignition.asp ), I feels pretty confident with my decision to go with the Crane XR700 setup.

So, questions:
1) Where do I buy/get it?
2) Should I replace the coil?  With what? I think I'd like the Bosch 26KV coil, but how do I tell whoever I'm buying it from, exactly what I want?
3) Should I replace the 6 spark wires? With what, EXACTLY? I've read *WAY* too much about solid copper core wire and screwing ends on!
4) Should I replace the distributor cap?

NOTE: my car's Transistorized Ignition Module got baked way back in 1976. Someone did a pretty darn good job converting the car to non-transistorized ignition - and it's run this way ever since. I'm hoping they used the orignal distributor. How can I tell?


--
~~~~~~~~~~~~~~~~~~~~~~~~~~~
William Blair Wagner: blairwag@earthlink.net
Education is not always knowing the answer,
...but rather knowing where to look for it!
~~~~~~~~~~~~~~~~~~~~~~~~~~~

[Cees Klumper]

John Hassle, last March, made a VERY comprehensive, 30-page document, explaining the installation of the Crane XR 700 system. It's in .pdf format and I kept it "for later". The title is:  "Crane XR-700 Optically-Triggered Ignition System - Installation Instructions and Tips". It includes a primer on ignition systems and many diagrams, drawings and photos. I will send it to you next. It's too large a file (500k) for posting on this site, but we'll be sure to include the information in the Ownership, Repairs and Maintenance Manual we're working on at the moment. Anyone else interested, email me off-line and I will send it to you.

John Hassle also said the following about cost and where to get the Crane system: "I got it on-line directly from Crane.  The total was about $100 (as I recall) including shipping.
Their web site is:  www.cranecams.com"


Cees Klumper in Amsterdam
'69 white 280 SL automatic

[n/a]

Hello..

I am not familiar with the Crane, but installed the Pertronix unit.  It's pretty unobtrusive, with the only obvious addition an additional wire running to the distributor.  It greatly improves low RPM spark, as well as improving high end performance.  I stayed with the stock spark-coil, but may re-evaluate after I have more time on the engine.

I always replace the wires and distributor cap when converting.  This reduces the chance for introducing too many variables for a solution.

If you want to stay stock, and if the bakelite end pieces are still good, it's pretty easy to rebuild.  I would use low resistance silicone wire (black) from a speed shop, but you can also buy pretty accurate OEM stuff in bulk.

Don't know which distributors go with which years, but I have a '69 and '71 engine that both had the '051' distributor (last three digits on part number), so my guess is that is what yours should have.

FWIW

[Naj ✝︎]

Rasuth,

There are some comments that the Pertronix causes slight misfiring mid-range (around 3000-3500 rpm) and above 5500 rpm.
What distributor do you have and your experience??
naj

naj
'Kloines Scheisserle'
65 230SL
68 280SL

[n/a]

Could be..

I still have an intermittant 'stumble' on acceleration around 5000 rpm.  No problem at all at 3000-3500 rpm, and once I settle down around 5000 rpm it seems to clear up.  I suspect the problem is either injector or linkage related.  It could also be that multi-point spark plug will help (I am using Bosch Platinums, which have a funky 'wire point' design).

I am using an '051' distributor, and timing is set at 2deg ATDC at 800 rpm with vacuum.  Book says to use 6deg ATDC, but I couldn't set idle properly.  It is also possible that the cam is euro.. I haven't looked.  Advance curve is good, so this may also be my problem at higher rpm (with idle offset).  After the engine settles down (it's a transplant, so I need to run it awhile to clear it out) I intend to re-tune it.

I had two '051's and picked the one with the least cam lobe wear, but both seemed to run about the same (I was debugging, but the distributor wasn't the culprit).

[blairwag]

What about the ignition coil? Should I replace my stock one? The one I have is a black body coil (not blue). I'm not even sure if its a bosch. Anyway, is there a hotter coil that I should install with the XR700?

--
~~~~~~~~~~~~~~~~~~~~~~~~~~~
William Blair Wagner: blairwag@earthlink.net
Education is not always knowing the answer,
...but rather knowing where to look for it!
~~~~~~~~~~~~~~~~~~~~~~~~~~~

[n/a]

I stayed with the stock coil for now.

Bosch makes the 'blue coil' that puts out 26kV, and Pertronix has a version that puts out 40kV.  I'm sure Crane has something similar.  You will have to match the ballast resistor to the coil.

Whether or not a higher voltage coil improves things I will defer judgement on, since I have no concrete information.  However, I have seen significant improvement with multi-point sparkplugs (ala splitfire), and these plugs are supposed to work better with higher voltage coils.

[gwuisman]

Cees,
I am interested in Tom Hassle's document on the Crane XR 700 sytem.
Gerard Wuisman.

[Roadstir]

Blair,

My '71 280 has a Crane XR3000 system. (not much more than a 700)  This is the next one up from the 700.  Had a few problems recently, and thought it might be the XR3000 so I did a bit of homework to familiarize myself with the system.

I called Crane's tech support line and learned more than I could remember.  Plus, they have text versions in PDF form on their website.  The tech was surprised that the car had a 300 vs a 700.  Said that the 3000 was designed for hotrod and race applications.  It has a very hot spark, but it MUST be matched with a very hot coil.  They have a Crane matched coil, but he said that Bosch makes a compatible one also.  I got this one (silver) from Ray Paul.
VERY IMPORTANT: This system uses no ballast resistors!  Straight shot.  Also, you have no dwell specs- so don't waste your time trying to change it.  The electronic chip handles everything.  

Correct alignment of your optical eye inside the distributor is critical.  This is called "phasing."  If it's off the car runs like crap.  Oddly, according to the tech site, you can check this by punching a hole in the top of your distributor cap and using a timing light to check the phasing. (obviously, for testing purposes, this is done to a spare cap)  Since resetting this and buying new Magnecor wires, my baby runs much better.  Plugs are staying clean.

Hope this helped,

David

[jeffc280sl]

Recently purcahsed the Crane XR700.  John Hassle's write up is invaluable.  I'm not sure the average or maybe above average Joe could install the system without John's installation guide. The Crane unit will fit many distibutors and as such it is not installation friendly. Their instructions leave a lot to be desired. I spent a lot of time filing this and that to get the proper alignment of the shutter and LED trigger.  Then it is a fitting try and then take apart and file again.  It is very, very tedious.  John recommends taking the distributor out of the car in order to do a proper fitting.  I highly recommend this.  I tried to do it with the distributor on and got fairly close to complete but was just not satisfied.  With the distributor out you can more easily adjust the optical switch to hit on the leading edge of the slit in the shutter.  I hope to finish the installation tomorrow.  Need to go out and buy a timing light and rpm gauge.  I have some pictures if anyone would like them.  I have trouble attaching pictrues here.  If you want to look at mine you can contact me at lax882@aol.com and I'll send them to you.

Best of luck,

Jeff
1970 280SL 4 speed

[n/a]

Up to date..

I was reading a little MBZ book I scored called "Data for Passenger Cars" that has a bunch of consolidated info, including the 280sl, and decided that I needed to re-address engine tuning.

1)A fan shroud is only installed on cars with A/C (mine doesn't have A/C), so I put a fan shroud on to solve engine overheating problem that was probably caused by bad timing.

2) As noted in another post, the '051' distributor was used for 68/69 while the '061' or '066' were used for 70/71.  The '71 engine I swapped in had a '051' in it, so when I used the 70/71 timing procedure, this was wrong.  I don't have a tach that goes to 4500rpm (the engine I put in was an auto from an SE, so has no gear assembly to drive it, and I'm NOT going to take the head off to get it in there), so I used the 1-4 degBTDC w/o vacuum at idle (800rpm) to adjust.

So after timing, I reset the idle adjustments and fine tuned the linkages.  The car no longer has any stumbling on acceleration, and winds out to redline without a hitch (hard to tell where redline IS, though, so gotta be careful:-)  I have also not had any problems with overheating in heavy commute with 90deg+ temperatures.

From this, I would say that the Pertronix unit with a stock coil and Bosch Platinums works great.