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Finding top dead center

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I am assembling a 1.8L OHV Weber carb in an 82 Subaru Wagon 4x4. Just torqued my heads and now am trying to adjust the valves. How do I set top dead center on the distributor and flywheel? Neither is installed.

pull no. 1 spark plug, then insert finger into whole and turn crank untill the air pushing past you finger stops, go too far and it will start sucking air past you finger. Once you find where no air go past your finger this is tdc

  • Author

Now if I turn the crank to where the #1 exhaust valve closes and just before the intake opens, is that TDC or is that 180 out?

 

Now the rotor should point opposite number 1 at TDC? Because it is not on the compression stroke (fire)?

I just bought a piston stop, a 14mm brass screw. Screw it into the plug hole and rotate the crank till it stops. I backed it off untill it would just go past then cranked it in a hair until it stoped. TDC. Later, Tim

  • Author

I need to install the distributor and flywheel so I want to make sure I have it right, not 180 out.

ok, here's the easiest way I have found to help locate TDC.

 

First off, pull the number 1 plugwire off and take the sparkplug out

Then screw the plug back in a couple threads

Take a 22mm or a 7/8" socket on a breaker bar or ratchet and turn it clockwise

When the number 1 cylinder is compressing, the air will make a nice whoosh sound from between the threads

If it is on the TDC stroke, the air will stop and you'll see timing marks through the timing mark hole in the bellhousing

If not, then you're 180 out, just continue turning it untill it makes the whoosh sound again and you will see the timing marks

 

As for the flywheel, there's only one way it can bolt on. Set it on there and get the holes lined up but make sure ALL of them line up since there's a couple which are unevenly spaced, thus making it only one way to go on

The flywheel only goes on in one position. Remove the right side valve cover and rotate the engine until it is at TDC with both valves on #1 closed.

  • 1 month later...

just installed my motor and i think the distributor is off (car barely idles, at best). i can find TDC no problem, but then where do i put the distributor (on an XT6)? i know it's supposed to point to cylinder #1, but since the distributor housing is movable, depending on where the housing is (the 10mm hold down bolts) there are a few places where the rotor will line up with the #1 on the cap.

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