Flywheel was pulled without marking! Help

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Flossyb20

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Sep 13, 2010
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Guys - putting my 72 850 back together and realized that the flywheel wasn't marked when pulled off the crank (got the motor in pieces) - Is it as simple a setting the crank at #1 TDC, and lining up the pointer mark with TDC on the flywheel? I had to place the timing belt also, and set the timing off the flywheel mark, but she just won't fire. Getting good spark, and fuel, which leads me to believe this is a timimng issue. Thanks
 
j_martin

j_martin

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Re: Flywheel was pulled without marking! Help

Yep. Set the #1 piston as close to TDC as possible. Put the flywheel on with 0 degrees at the pointer.
 
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Flossyb20

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Re: Flywheel was pulled without marking! Help

Thanks..it seemed pretty straight forward, just wanted to check.
 
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Too Cycled

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Re: Flywheel was pulled without marking! Help

Newbie question ... what is TDC? Totally displaced crankcase is my best guess - ie. piston at full stroke?

Am I close?
 
Bifflefan

Bifflefan

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Re: Flywheel was pulled without marking! Help

Too Cycled said:
Newbie question ... what is TDC? Totally displaced crankcase is my best guess - ie. piston at full stroke?

Am I close?
Click to expand...

First, you need to start your own thread for question.

"T"op "D"ead "C"enter. is what it means.
Piston at top of stroke, rod exactly straight between piston and crank.
 
jerryjerry05

jerryjerry05

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Re: Flywheel was pulled without marking! Help

The flywheel should have a keyway on it the groove in the flywheel should match the groove in the crank.
Then top piston,extended all the way till it almost touches the plug.
Look at the flywheel it should be reading TDC.
There might be 3 hash marks these are for static and running timing.TDC is a mark by itself. Hope this helps.
The best thing is get a manual.The library has manuals or can get what you need.J
 
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Flossyb20

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Re: Flywheel was pulled without marking! Help

Thanks guys---looks like I got the timing set correctly. I got it to fire up, but I had to keep the starter engaged to do so (no spark when the switch is in the "on" position) I verified all the wiring to be good, so it looks like I'll be getting a new trigger. I'll let you know how it goes!!
 
j_martin

j_martin

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Re: Flywheel was pulled without marking! Help

Flossyb20 said:
Thanks guys---looks like I got the timing set correctly. I got it to fire up, but I had to keep the starter engaged to do so (no spark when the switch is in the "on" position) I verified all the wiring to be good, so it looks like I'll be getting a new trigger. I'll let you know how it goes!!
Click to expand...

Why would you figure the trigger is bad? Something about the switch position has to do with the ignition firing.

I don't know about this ignition, but it's theory and testing time, doubting everything, including "obviously good" wiring.

In old automotive stuff, there was a resistor that got jumped to improve the spark when cranking. If that resistor opened up, it would fail in the run position, but run in start position. Something similar is happening here.

hope it helps
John
 
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Chris1956

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Re: Flywheel was pulled without marking! Help

Jerry, Most Mercs have a W shaped key way, so the inner flywheel cannot be installed incorrectly. The outer flywheel is held on by 8 bolts and may be rotated to any of 8 positions, however, only one position is timed properly.

Flossy, Before springing for a new trigger, test to make sure there is +12VDC on the white and red wires on the non-distributor side of the switchbox. If the voltage is good, it is likely that your trigger is bad. There are some tests on the CDIElectronics website, for that.
 
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