Preferred Method: Align Distributor?

[jakl]

Hi Folks,  I need to install the correct distributor for my '70 280sl US.  What is the preferred method for aligning marks at TDC?  Should I rotate the crankshaft or "bump" engine with starter?  BBB does refer to manually rotating the crankshaft - however, I've read posts on this site to the contrary.  Please advise.
Regards,
-jakl

[Cees Klumper]

I always just turn the crankshaft (clockwise of course) with a 27mm socket + a short extention. Once you get used to how to do this it is quite easy. Although it's done from below the car, so not possible to see what you are doing and it may take several individual movements to get it to where you want it (cam lobes No. 1 cylinder both pointing up?). I have yet to figue out which of the pins on the firewall starter inhibitor jump the starter and try that sometime.

Cees Klumper in Amsterdam
'69 white 280 SL automatic

[Ben]

I think the problem with some cars is its difficult to get a socket onto the crank if you have auto, p/steering and a/c.

Mine doesn't have any of that and I use the following because its manual, I simply jack up a rear wheel and put the car in gear then turn the wheel 'till I get the spot !

You can "bump" the starter but its less accurate and may take a few attempts. Neither way can cause damage !

Regards,
Ben in Ireland.
'64 230SL 4sp.
'03 CLK Kompressor

[ja17]

Hello Jakl,
Removing the sparkplugs will help ease turning the engine.



Joe Alexander
Blacklick, Ohio

[hands_aus]

Hey Cees,
All you need to do is to separate the plug top from the body of the neutral safety switch. Then apply +ve 12v to each of the sockets and see which of them causes the engine to rotate.
On mine it was the top left socket as you look at it facing the radiator from the windscreen.
To be sure the engine won't start you can remove the coil wire to the distributor.
I wish I had done that before installing my new points. This was before installing the Pertronix unit.
cheers

Bob (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[TheEngineer]

On my car there is a two terminal connector on the right forward side of the engine, just under the air conditioning compressor. Try to obtain a voltage reading against ground when another person operates the starter. That way you locate the terminal which turns the starter and you can buy a handheld momentary starter switch at your friendly parts house and use it to bump the engine. I've used a socket with a 2 inch extension and my ½ inch ratchet on the screw buried in the v-belt pulley in the front of the engine or I've also removed the small cover plate on the fwd. side of the flywheel. Then I had access to the bolt-heads where the hydraulic clutch fastens. You can turn the engine from there too.

1969 280SL,Signal Red, A/T, P/S, A/C, Both tops.    Ret. engr.

[Cees Klumper]

By the small cover plate, do you mean the one on the viscous fan coupling? If so, I never knew these came off - I have had a tough time removing the fan assembly off its pully because the four 10 mm bolts  are impossible to get a good grip on.

quote:Originally posted by theengineer

I've also removed the small cover plate on the fwd. side of the flywheel. Then I had access to the bolt-heads where the hydraulic clutch fastens. You can turn the engine from there too.

1969 280SL,Signal Red, A/T, P/S, A/C, Both tops.    Ret. engr.

Cees Klumper in Amsterdam
'69 white 280 SL automatic

[blairwag]

I have never had enough success with the "bump the starter" approach, to recommend it to anyone. People say you may need to do it several times to get it right.... yea, maybe several hundred times, if you're trying to really get TopDeadCenter!
Best approach is like Cees initially said - put a 27mm socket on the crank nut with a shorty extension, and use a 1/2" rachet to turn the crank. Someone else watching the harmonic balancer for the TDC mark is most helpful. Otherwise, you will be getting up and down a lot. If the thing is too hard to turn, remove all 6 spark plugs to eliminate cylinder chamber compression. This makes it a LOT easier.

One thing is for sure, IMHO - NOTHING is easy to do on this car!   ...so don't bother looking for the easy method of accomplishing something (like bumping the starter to find TDC). Just take the extra time, energy, and resource to do it right.  ...just my humble opinion.

--
~~~~~~~~~~~~~~~~~~~~~~~~~~~
William Blair Wagner: blairwag@earthlink.net
Education is not always knowing the answer,
...but rather knowing where to look for it!
1971 280SL US Automatic
~~~~~~~~~~~~~~~~~~~~~~~~~~~

[ja17]

Hello William,
It will get a lot easier after the foruth or fifth time!

Joe Alexander
Blacklick, Ohio