jacksheadache
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Fiding top dead center
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MAKG
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TDC is, by definition, where the piston is has high as it will get.
TDC on #1 is just what you describe.
But people usually want TDC on #1 on the compression stroke, which also means that both valves are completely closed (on TDC/exhaust, they will both be slightly open). One way to do this is to feel the air come out the spark plug hole as the crank is rotated through the compression stroke. Another is to remove the valve cover and see if both valves are closed.
Timing marks on the crank dampener usually correspond to the position of #1.
TDC on #1 is just what you describe.
But people usually want TDC on #1 on the compression stroke, which also means that both valves are completely closed (on TDC/exhaust, they will both be slightly open). One way to do this is to feel the air come out the spark plug hole as the crank is rotated through the compression stroke. Another is to remove the valve cover and see if both valves are closed.
Timing marks on the crank dampener usually correspond to the position of #1.
jacksheadache
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MAKG
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No, that's more or less it.
Make sure you look at the piston height or crank markings as well, as those are much more precise than feeling the air.
Make sure you look at the piston height or crank markings as well, as those are much more precise than feeling the air.
jacksheadache
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How accurately do you need TDC? The piston is at the top for a lot of degrees.
With a 4.0 there is no distributor to get confused by. I'm curious to know what you are doing.
If you really want TDC you need a piston stop and a pointer and a degree wheel, although the crank dampner works too. I didn't make a piston stop for my 4.0 because there's no need, but I've made them for every other engine I've ever dismantled. You take an old sparkplug, knock all of the porcelin out of it, thread the center for a bold, run the bolt into it, smooth the end so it won't damage the piston and there you are.
Then you get a piece of coat hanger and use your dikes to cut one end at a sharp angle to make a point. Find a bolt near the crank pulley, cut the wire, make a look in one end and play with it so that it is pointing at the degree wheel or the dampner. Then put in the piston stop into the #1 plug hole. Gently rotate the engine until you feel air coming out the hole so you know it is on the compression stroke. Then start turning the bolt into the cylinder until it touches the piston. back the bolt and turn the crank until the piston is as high as you can get it. Make a mark on the dampner.
Now turn the engine backwards until the piston again touches the bold. Make another mark on the dampner. Halfway between them is the real TDC. Get a slip of paper, hold it on the dampner, transfer the two marks you made onto the paper, fold the paper so those marks meet--the fold is the halfway point. Put it back on the marks, mark the halfway point on the dampner, take the piston stop out of the hole and move the engine counter clockwise to take up chain slack, and then clockwise until that exact point is under the pointer. That's TDC. At that point the timing marks and factory pointer on the motor should show 0. If the motor is apart for camshaft work, you are ready to proceed with that.
With a 4.0 there is no distributor to get confused by. I'm curious to know what you are doing.
If you really want TDC you need a piston stop and a pointer and a degree wheel, although the crank dampner works too. I didn't make a piston stop for my 4.0 because there's no need, but I've made them for every other engine I've ever dismantled. You take an old sparkplug, knock all of the porcelin out of it, thread the center for a bold, run the bolt into it, smooth the end so it won't damage the piston and there you are.
Then you get a piece of coat hanger and use your dikes to cut one end at a sharp angle to make a point. Find a bolt near the crank pulley, cut the wire, make a look in one end and play with it so that it is pointing at the degree wheel or the dampner. Then put in the piston stop into the #1 plug hole. Gently rotate the engine until you feel air coming out the hole so you know it is on the compression stroke. Then start turning the bolt into the cylinder until it touches the piston. back the bolt and turn the crank until the piston is as high as you can get it. Make a mark on the dampner.
Now turn the engine backwards until the piston again touches the bold. Make another mark on the dampner. Halfway between them is the real TDC. Get a slip of paper, hold it on the dampner, transfer the two marks you made onto the paper, fold the paper so those marks meet--the fold is the halfway point. Put it back on the marks, mark the halfway point on the dampner, take the piston stop out of the hole and move the engine counter clockwise to take up chain slack, and then clockwise until that exact point is under the pointer. That's TDC. At that point the timing marks and factory pointer on the motor should show 0. If the motor is apart for camshaft work, you are ready to proceed with that.
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