Finding top dead center for valve adjustment

steve706 · Jun 20, 2010

I have a 706 gas that I just rebuilt the top end on and now have to adjust the valves. The pully is supposed to be marked but it's not. What is the easiest way to find tdc on the #1 piston?

mike in mo · Jun 20, 2010

pull the #1 plug turn motor till you get a gush of air then stick some stiff wire in there and turn the motor till the piston is all the way up.

DeltaRed · Jun 20, 2010

Look to the right side of the flywheel/clutch housing,remove the little two bolt inspection plate.the flywheel will have timing marks,line up 0degrees with the pointer,you should be there.thats how my diesel is,not sure if gas is same.Good luck

Brad Gyde · Jun 20, 2010

It could be like my case 930.. I was right there with you.. no way it was marked.. Took a small "toothbrush" sized wire brush and really went to scrubbing on the pulley and I'll be dipped if the numbers didn't begin to show through the rust, dust, and thick paint.

Not saying you didn't already do the same, or that you'll find the numbers if you do such as I did.. Just trying to offer some advice as to what worked for me.

Brad

DickL · Jun 20, 2010

If all else fails, with the valve cover off to adjust the valves, you might notice that the rocker arms are all the way up at TDC. That would mean that the cam is at its lowest area where you would make the proper adjustment. No need to be exact on TDC as the cam will be the same diameter after you go past the lift lobe.

John M · Jun 20, 2010

Dont know your specific tractor as far as working on one, (have driven a few thought) but Ive never worried about TDC to set a valve, as long as its closed. I also set whatever other ones are closed while Im there and havent had any problems so far.

old · Jun 20, 2010

TDC way is the hard way. The easy way and the one 100% sure way is to do this. When the exhaust valve is open then adjust the intake and when the intake is open adjust the exhaust then and only then can you be 100% sure to have the valves so they can be set right. Ya old school no brainer way of doing things and I was shown that 40 year ago

teddy52food · Jun 20, 2010

If you watch the valves on # 6 they will just be closing the ex & opening the in as it rocks over TDC.

RodinNS · Jun 20, 2010

Pull the spark plugs. Knock the flux off a welding rod. Stick in hole and watch until is stops rising. You just found TDC...

Rod

Bob · Jun 20, 2010

A simple length of electric fence wire is CHEAPER and you don't have to knock the flux off!

RandyB(MI) · Jun 21, 2010

Not that you have to know exact tdc to set valves , but if you want to mark your damper/pulley exact tdc here is how. Find a bolt the same thread as your plugs but 1/2" longer or so. Thread in the bolt and slowly turn (by hand) the engine until piston comes up against the bolt. Make a mark on the damper at this point. Now turn it back the other way until it comes up and hits. Make a mark there on the damper. Now take a tape and measure the distance between the marks and find exact center between marks. This IS EXACT TDC! Mark it and go by it. On a car sometimes the harmonic ballancer which is isolated fron its hub by a ring of rubber or other elastomer , has slid around or moved slightly from factory position. If you are not replacing it with new , this is a good way of checking it for proper tdc. No mater what the situation , it is nice to know true TDC!

Finding top dead center for valve adjustment

steve706

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mike in mo

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DeltaRed

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Brad Gyde

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DickL

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John M

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old

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teddy52food

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RodinNS

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Bob

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RandyB(MI)

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