450SL noobster

[Grenadiers]

Just bought a 1975 450 SL from AlanTbird here on the board. Ok original condition, wife just spent a day cleaning the interior, and resurrecting the powdery white exterior paint. Looks much nicer!

Car runs pretty good, has the upgraded ignition module, Crane XR700, EGR delete, Catalytic converter delete. We're at 7200 feet here in the Sacramento mountains of southern New Mexico. Car ran great from his place to that elevation, and it started to cut out, a lot. Runs rich, at any elevation, adjust the MPS? Don't have wideband system available, not going to spend 200 bucks on this one, have one in my 924 Porsche turbo though. The car is very nice, rust free, but is a gutless one at best. Concerned about the cutting out though, any hints? Seems to be worst at going up hill, and at altitude. thanks, dave

[bwostosh]

Start with fuel filter and/or fuel pressure on a hill climb especially.
Do the air filter while you are into it.
Crane is a great improvement no problem with spark.

[Graham]

I seem to recall that car being discussed on Benzworld

Here is one thread, there may be more. May explain some of the problems:

update on the ole 75 450 sl - Benzworld.org - Mercedes-Benz Discussion Forum

[Grenadiers]

Ah, got that, thanks. Car is running much better, we're at 7200 feet so a bit rich at the moment. I have two K-Jet 924 Porsche turbos, so am familiar with working on really old Bosch systems. We have 250 miles or so on the car since we bought it from Alan, and the cutting-off problem seems to be going away.

Wife scrubbed the red interior to a very nice condition. And, she brought back the white paint from the dead. Rubbing compound and then a coat of wax. Car is actually cosmetically very appealing. For speed, I have my '85 911, so the grumpy V8 in the 450 is for cruising the neighborhood. Wife driving of course. Car is going back to WI this winter, and to storage. I'll look into the leak down numbers when we get back in the spring.

[RadioTek]

Since you've got the Crane ignition, you're ahead of the game already. I had to go to that on mine, due to distributor shaft wobble eating the follower on the points.

The two places to look first would be to your timing and the fuel/air mixture. The ECU is "primitive": It can control a few things, but dealing with an altitude change of that order is a bit much. The absolute air pressure at 7000 feet is HALF of that at sea level, so things will need to be 'tweaked' a little to get it running right.

I wish I could delete my cats, but Arizona's emissions control equipment cutoff is 1969.

Good luck,
Scott

[Grenadiers]

Question, tach is inoperative, where does one start on the diagnosis? Thanks, dave

[AZreGuy]

Two things.
Radio, I live in Phx and do not do the emission test as I put Historic plates on my 75 450SL.

I just looked at the Crane 700 and need to ask, is there HEI in a later year SL? I added a late model Chevy HEI distributor to my '68 Chevy, drop and go!

[RadioTek]

Starting in model year '76, Benz changed from the D-Jet system to the K-Jet. They went to a Hall-effect trigger for the coil pulse, from the breaker points of the D-Jet system.

There have been a couple of people that have put a Pertronix on a '75, but it required some work to get the brackets right. A Crane unit doesn't require the modifications of the plate in the distributor that the Pertronix, but it does replace the switchgear behind the headlight. and you need to put a resistor in the circuit to get the tach to work.

Scott

[rdts]

Originally Posted by RadioTek

Starting in model year '76, Benz changed from the D-Jet system to the K-Jet. They went to a Hall-effect trigger for the coil pulse, from the breaker points of the D-Jet system.

There have been a couple of people that have put a Pertronix on a '75, but it required some work to get the brackets right. A Crane unit doesn't require the modifications of the plate in the distributor that the Pertronix, but it does replace the switchgear behind the headlight. and you need to put a resistor in the circuit to get the tach to work.

Scott

He! Saw your mention of the Crane Ign System. I have a 1972 350/450SL and wanted to put the Crane Optical in it. You don't happen to have any part numbers and step by step instuctions laying around, would be greatly appreciated as I just ordered new point set (no condensor on my setup) Cap and Rotor etc. would love to ditch the points!!

[RadioTek]

It's been a while since I did mine, but it was pretty easy. The hardest part was fabricating a plate to screw the Crane/S&S unit to that bolted to the place the stock Switchgear rested.

Basically, you remove the points, and use the old screw hole to put the bracket for the sensor, then put the shutter wheel on the shaft, run the wire to the new switchgear, tie the other wires to the coil and ground, line it up per the instructions, and then set your timing. However, the devil is in the details.

First, try to set your engine at #1 TDC, the rotor under the cap should be pointed at a mark on the edge of the distributor. This can be done by putting a 27mm socket on the crankshaft bolt and turning, or by pulling on the power steering belts(didn't work for me, but some people have been able to turn the engine). You could also 'bump' the starter, but this requires a bit of luck to get it exact. This simplifies things a lot, when you are trying to get everything adjusted.

When you have the car set to #1TDC, you should have the rotor pointing at the tiny mark on the edge of the distributor, where the cap mounts. Try to get the timing pointer to point to -0- degrees advance/retard on the harmonic balancer as close as you can. You should be able to remove the points and rotor, and put the shutter window on the distributor shaft. I used the one with the metal tensioning clips on the bottom, with the flat side up. You might want to take a Dremel and skim off the little ridge, to give your rotor more room to seat. You'll have to put the pieces of the bracket together on the sensor, and then attach to where the old points were screwed down. You'll have to finagle things a bit to get the sensor around the shutter wheel, making sure there is no touching of the wheel and sensor.

Then the wiring is run from the sensor out to the module connector. Make sure when you put the connector on, that you have the colors match up EXACTLY, the connector is polarized, and only can be put together one way, so be careful to get this right.

I decided to fabricate a plate to let me bolt the new module into the same place that the old module was. I got some 1/4" aluminum plate and cut and drilled as needed.

There are three wires from the module that go to the coil. The black is a ground, which I put a new connector on and used a coil hold-down bolt for the ground. The red one goes to the + side of the coil, and the red one goes to the - side of the coil. The wires from the old Switchgear connector I folded back out of the way. You should have two wires to the + side of the coil, and one to the - side.

You should be able to turn the key on, into the run position, and watch the red LED on the new module. You should be able to adjust the backet and sensor to just turn on the LED when you get the sensor and bracket to the right place, then tighten it down.

With a bit of luck, you should be able to put the rotor and cap back on, and start the engine. Set the timing to the specifications in the M-B manual, and you should be in for years of no worries about your points going out of adjustment on you.

NOTE 1:
--------
This is done from memory, with a few interruptions, so READ THE INSTRUCTIONS SUPPLIED WITH THE UNIT. If there are any differences, go with the instructions, rather than this.

NOTE 2:
--------
The tach will not be working now. To get it to work, I had to make a wire with a 6.2K Ohm resistor, and run it from the - side of the coil to the test terminal on the fender, where the tach lead was attached. Since I am not near the car, and don't have photos with me, I'll have to edit this when I get home with my camera to clarify things.


Hope this gives sort of an 'idea' ofwhat is involved, until I can get to my car with the camera.

Scott




The

[Graham]

Originally Posted by rdts

He! Saw your mention of the Crane Ign System. I have a 1972 350/450SL and wanted to put the Crane Optical in it. You don't happen to have any part numbers and step by step instuctions laying around, would be greatly appreciated as I just ordered new point set (no condensor on my setup) Cap and Rotor etc. would love to ditch the points!!

With the 72, the Pertronix works well and is an very simple and inexpensive install. I have just the $70.00 basic point replacement on my car (part 1885). But some have gone the next step and bypassed the MB switchgear and added a Flamethrower coil at same time. I bought mine here

[RadioTek]

For a '72, the Pertronix is less expensive, and a bit less of a hassle to install. Rverything is inside the distributor cap.

For some reason, I was thinking that you had a '75, like me. There are some problems in trying to get a Pertronix into a '75. The changes to the mounting plate in the distributor of the '75 is different than earlier years, as M-B added a vacuum retard function to the vacuum advance system. It reputedly has been done, but it required some modifications to the mounting plate that I didn't want to try.

Scott

[Grenadiers]

We've decided to sell the 450SL, haven't used it much since we bought it. Ran a few bottles of Techron thru it and it runs quite nice now. Not sure if engine is tired as previously mentioned, we're still at 7200 feet, but it doesn't cut out any longer. We're moving to Prescott, AZ and plan on hauling it there. Will be in the Cloudcroft, NM for another month. So, car can be available either here or along I-10 to Prescott. Here are some pics:



Mercedes 450SL Cleaned pictures by rangerpearl - Photobucket

I don't come to this site too often, so a phone call works great. 5756872536 dave

[RadioTek]

You might be surprised at how much you could drive it in Prescott. The climate is fairly mild, and there are a lot of highways to drive. A nice run up to the Canyon would be a nice trip.

Just my 2 cents.
Scott

[Grenadiers]

yeah, but, but, but, but, I have an '85 911 for that~!

You can see it in one of the pics in the album.