Timing and plug wire location? - PeachParts Mercedes-Benz Forum

JBR · #1 03-20-2006, 05:14 PM

73 450sl- I still can not get 5*atdc. I am wondering if the wires are on the wrong plugs.
1st question- Spark plug location, Is this correct? Passenger side front plug is #1 cly. Next is # 2 and so on till the back passenger side plug is # 4 cyl. Then on the drivers side, front plug is # 5 cyl and going to # 6 and so on till #8 cyl is back plug on drivers side.

Next- Looking at the dist cap. Plug wire to #1 cyl is on the post at 1:00. going clockwise around the cap what cly wire goes next about 2:30 and so on. any help please Thanks

autozen · #2 03-21-2006, 12:31 AM

Your cyl numbering is correct. Pull the dist cap. A small line on the edge of the dist housing marks #1 cyl. The dist rotates CW. The firing order is cast on the topside of the valve covers. It says: ZUNDFOLGE. You can check for #1 by removing the right bank valve cover and checking for rabbit ears.

JBR · #3 03-21-2006, 06:08 AM

Thanks for the help Autozen: If I understand you correctly.
Firing order 15486372
Looking at dist. cap (1:00) is #1 cyl now going ccw (11:30) should be #5 cyl plug wire. still going ccw around the cap (10:00) would be #4 cyl plug wire. and so on. If this is true, mine is not even close. This could be why I can not time it to 5*atdc. What do you think. Thanks

autozen · #4 03-21-2006, 10:24 AM

If that is the firing order you got off the valve cover, then that is correct. I don't know the firing order from memory. The dist turns CLOCKWISE. You can pull the cap and ground the high tension lead from the coil to protect the ignition module and have someone crank the car. You will see the dist rotate CW and you will see a little line on the edge of the housing that looks like it was made with a chisel. That should be #1 if it hasn't been screwed with. TIP: I made a spewcial tool that I did not give an MB part # to. I fashioned a coat hangar to hook into the dist cap and into the metal stiffener at the firewall end of the hood. That keeps the SOB out of the way while you are working on the dist.

JBR · #5 03-21-2006, 11:17 AM

Maybe I am not correct. In my discription on how to locate the plug wires on the cap. I was saying to put them on the cap in the correct firing order but putting them on counterclockwise on the cap. Since the dist. turns CW then shouldn't I put the wires on the cap in a CW manner?

Tomguy · #6 03-21-2006, 12:48 PM

1:00 should be #1. Then go clockwise indeed with 5, 4, 8, 6, 3, 7, 2. #5 should be at 2:30, not 11:30. #4 at 4:00.

What do you mean "Cant get to 5° ATDC" - are you too advanced (0°, 5° BTDC) or too retarded (10° ATDC)? The car will start and run at 0° or 5° BTDC. It MIGHT at 10° ATDC, but not well.

JBR · #7 03-21-2006, 03:08 PM

Thanks Tomguy: Re: to the timing question. The closest I can get to 5* atdc is 10*btdc. The slot in the dist. mount is all used up when trying to turn.
My plug wires are all f** up I will work on it a little tonight. Thanks

Tomguy · #8 03-21-2006, 03:52 PM

You know turning the dizzy CCW will retard I assume... if that's as close as you can get, you might be off by two teeth and not just 1 on your rotor. Like I suggested in your previous thread, pull the dizzy out, and rotate the shaft a tooth counterclockwise. Then try setting your timing. Alternatley, pull the plug for the #5 cyl and put the plug from the #1 cyl on it, and move each wire back one position (5 then goes where 4 was, etc). Lazy man's fix. It will work fine assuming you can get it to be not too retarded this way, just your ignition and injector timing wont match exactly - not a big deal with the D-Jet injection system.

JBR · #9 03-22-2006, 06:14 AM

Here is how it all started:
The car ran rough so I removeed the dist. cap and cleaned,set dwell to 30* That helped.
I checked timing, it was at 10*btdc. The dist was turned all the way clockwise. I turned counter clockwise and idle would go right up and timing would move to 15*btdc. Thinking that was wrong I pulled the dist. and rotated the rotor cw maybe 1 tooth did not work. Tryed again ccw still would not work. I put it back the way it was and it ran. Still not satisfied.
I pulled the dist. removed the trigger points and cleaned.
this might be where I really screwed UP.
When reinstalling the trigger points I noticed.
I did not know where the dist shaft was located when pulling the points out so I just put the tray back in thinking it shoud make no difference.
Second The tray had a gasket around the surface that mates withe the dist housung. It is long gone. So when the tray is installed it goes in and with a little wiggle it goes in further, but still leaves gap of about 1/16" which I filled with RTV.
I have the timing so screwed up now it won't start at all.
I have tried to get the #1 cly on TDC by using the key I can only get close.
I can not turn the crank with a wrench, of course you can not see the nut on the crank when its 6" inside the multi groove pulley. I have used 30mm down to 18mm trying to find the size. The engine willnot turn over using the v-belts or power steering pump. I will pull the plugs and see if I can then turn it over to TDC #1cly on compression stroke. Then set rotor to #1cly. and start over.

Tomguy · #10 03-22-2006, 10:14 AM

The crank bolt should be a 27mm if memory serves. Remember, at 0°, the #1 cyl could be at TDC during its firing or its just closed the exhaust valve and is about to open its intake valve (in which case the rotor should be pointing to the #6 cyl). If you arent sure, you can probably tell by looking at the cam lobe positions when you pull the oil filler cap. At TDC for the #1 cyl, the exhaust lobe will probably be somewhere around 45° pointing towards the driver's side, the intake 45° pointing towards the pass side.

Once you have the engine at TDC, you can check to see if the distributor is close to TDC or not. If your timing is 10° BTDC it should still start - so you're probably off by 360° +/- whatever timing value you have indicated. In this pic of a distributor you can see the TDC notch by the screw labeled #4 at the top. You want the rotor to be on this mark (or a bit "behind" it in the CCW direction) when the rotor is fully counterclockwise. Remember, these distributors have a mechanical advance, and the rotor will possibly be slightly more clockwise when the car is idling.

When pulling the trigger points, it doesn't matter where the rotor is. As long as you reinstall the points with both screws you're fine. As long as the points open and close (and are plugged in so the ECU knows when they do) your engine will run if your timing is on. Now, it might run like crap if they stay open or closed too long, but that's something else! As for the plugging them in part - I've closed the hood and forgotten this at LEAST twice! I'm sure others have too.

autozen · #11 03-22-2006, 10:48 AM

That pic of the dist that Tomguy included shows the notch I'm talking about. Here is what I suggest you do to get out of this mess. Follow my instructions to the letter and forget all about 5* and 10* before or after for now.

#1 Pull all the plugs.
#2 Remove the right bank valve cover.
#3 Rotate the engine CW while you are facing the front of the engine. You should be able to do this with a 22mm on the P/S pulley. Rotate until you get what is called in the profession as " rabbit ears" on the right cam. That is both lobes up and line up the marks on the cam gear and cam tower. You are now at TDC.
#4 Pull dist cover and see where rotor is pointing. If it isn't pointing to that little mark in the pic, pull dist and drop back in with rotor on mark and dist hold down bolt in middle of slot.
#5 Noting which wire tower on cap matches location of the notch, install cap.
#6 Install wires in proper firing order starting with that tower being #1 going in clockwise dir.
#7 There is no #7. You are done. Start the car.

Good luck

Tomguy · #12 03-22-2006, 11:13 AM

And again, a link to my timing chain article: The very first pic shows what you need to align.
http://www.peachparts.com/Wikka/M117TimingChain

The slot on the washer should line up with the mark on the tower by where the oil tube is.

JBR · #13 03-22-2006, 12:19 PM

wOw you guys are great! I will do just what Autozen said, and Tomguy you really have a great article there, I hope I do not have to use it.
Thanks again. Cheers