Author Topic: Finding top dead center...?  (Read 3115 times)

cattledog

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Finding top dead center...?
« on: July 22, 2017, 21:17:55 »
Hello,
I bought the electronic ignition kit from mercedessource.com and first step in the instructions call for the engine to be brought to top dead center.

So far I have located cylinder 1's connection on the distributor.   I thought I could get close to tdc by cranking the engine until the stator pointed at cyl 1.   Each time I try to crank the engine to this position I end up passing tdc and ending up about 20 degrees past the 0 mark.

Is it possible to manually rotate the engine with a socket?   I looked at the crank pulley and can't see how a socket could fit in there.

Or is there another technique I should try to find tdc?

I don't suppose skipping the step of finding tdc and moving ahead and installing the new ignition, removing the points etc is possible?

The ignition kit is the same as a crane xr 700 in case that helps.

Chris

johnk

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Re: Finding top dead center...?
« Reply #1 on: July 22, 2017, 22:44:47 »
you can rotate it precisely with an 1 1/16th socket on the bolt on the front of the crankshaft pulley. Sorry I don't have the metric equivalent. My metrics did not go up that big an 1 1/16" inch fit precisely. Access it from below.
John Krystowski
Avon Ohio
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cattledog

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Re: Finding top dead center...?
« Reply #2 on: July 23, 2017, 01:16:12 »
Thank you John.    I will get a 1 1/16 socket on order right away.

Chris
« Last Edit: July 23, 2017, 01:53:17 by cattledog »

Cees Klumper

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Re: Finding top dead center...?
« Reply #3 on: July 23, 2017, 03:30:57 »
From memory it's a 27 mm socket. It's a tight fit but works. Only turn clockwise. Don't forget to remove the socket when done (don't ask).
Cees Klumper
1969 Mercedes 280 SL automatic
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stickandrudderman

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Re: Finding top dead center...?
« Reply #4 on: July 23, 2017, 08:16:29 »
If it's a manual gearbox just put it in 2nd with the park brake off and push the car to get TDC.
It's easier if the spark plugs are removed.
With the plugs removed you can turn the engine from the PAS pump or the alternator too, just use your spare hand to add extra tension to the belt.

Jonny B

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Re: Finding top dead center...?
« Reply #5 on: July 23, 2017, 15:00:32 »
Can confirm what Cees wrote, 27 mm socket. Also helpful when doing the valve adjustments.
Jonny B
1967 250 SL Auto, DB 568
1970 280 SL Auto, DB 904
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