Whats the easiest way to find Top Dead Center

[FuzzyDunlop]

I need to find Top Dead Center on my MR2. What is the easiest way?

 

[natto fire]

If it's not marked on the cam gear or harmonic balancer (usually at least 1 is marked, and a lot of times both) then you pull the #1 sparkplug and put a dowel rod in the hole. Rotate the crank until the dowel gets to it's highest point.

 

[Eli]

The dowel method will work, but a dial indicator would be better. I know you want more mechanics tools.

 

[Ronstang]

If it's not marked on the cam gear or harmonic balancer (usually at least 1 is marked, and a lot of times both) then you pull the #1 sparkplug and put a dowel rod in the hole. Rotate the crank until the dowel gets to it's highest point.

You have a 50% chance using this method. You need to make sure you are on the compression stroke. Pull the #1 plug and rotate the engine manually with you or a friend holding a finger over the spark plug hole. You will feel air coming out of the hole once you are on the compression stroke. Then simply move the crank pulley to align with the timing mark. If there is no timing mark then you can use something like a dowel rod.

The important factor is how accurate do you need to be? If you need accuracy and there is no timing mark you will have to add one. In this case you need to buy or fashion a piston stop to thread into the spark plug hole on #1 cylinder. Then you simply turn the engine by hand until you are close to TDC and then adjust the piston stop until it contacts the face of the piston. You then turn the engine counterclockwise a little to come off the stop and then gently turn it back clockwise until you make contact with the stop. You then make a mark on the crank pulley using some fixed point on the engine as a reference. You might have to fashion a pointer out of wire and attach it to a bolt. You then turn the engine almost one full revolution counterclockwise until you gently hit the piston stop once more. Mark the pulley once again. Halfway between the two marks on the pulley is exactly TDC.

 

[Pacfanweb]

Assuming the harmonic balancer has not slipped and the mark is off, all you have to do to get #1 to TDC is rotate the engine until 0 degrees is even with the TDC mark. Or TDC mark is even with whatever indicator your particular engine has.

IF nothing has slipped, that is the absolute easiest way to get any engine to TDC.

Now, if there is no mark for some reason, the dowel down the plug hole will get you close. I dial indicator will get you almost exact.



Here's how you do it using a piston stop:
First, you are going to have to make marks on the balancer, so use either the timing tab, or a piece of coat hanger, etc. that is bolted to the engine somewhere that can function as a FIXED pointer.

NOW:
Get the piston to JUST BEFORE top dead center, using a dowel, pencil, whatever.
Set the stop touching the piston.

Mark the balancer at whatever you used for a pointer/indicator/timing tab/etc.

Rotate the engine back the opposite way until it touches the stop again.

Mark the balancer at the same pointer.

Exactly halfway between those two marks on the balancer is TDC.

I think that's what Ron meant, but to me it didn't read that way, so here it is, clarified. (I hope)

 

[exdeath]

Way too much over thinking. Crank is keyed... Key points up at #1 tdc parallel with the cylinders. For TDC 0 deg or 360 deg just look at the valve train. Anything with timing marks isn't going to slip unless the key is sheared, highly unlikely with a 100 hp 4 cyl.

 

[Pacfanweb]

Anything with timing marks isn't going to slip unless the key is sheared, highly unlikely with a 100 hp 4 cyl.

I wouldn't say that. Most older V-8 balancers are 2-piece, and I've seen lots of bone-stock engines where the outer part of the balancer has slipped and the marks are off.

That said, I have no idea about the OP's motor. We also have no idea what state of assembly the motor is in, or WHY he needs to find TDC.

If he just needs to set/check timing or install a distributor, the dowel in the plug hole is good enough. If he's trying to set valve timing, he needs to be dead-on, and a more exact method is needed.

 

[FuzzyDunlop]

all good info guys. thanks.
Im a fool though, I should have done a little more research before bothering you guys, cuz this guy covers it thoroughly in his blog...
Image and quote courtesy of padandwheels.com

The green arrow is pointing to the timing pointer. That is going to be your reference point. You need to find this before you are able to do any kind of adjustment. (You may want to find this first with a regular flashlight, if you aren't sure where it is located.) The 3 notches on the crank pulley, that the different colored arrows are pointing to, are indicators telling you where TDC (top dead center, yellow), 10 degrees advanced (blue), and 16 degrees advanced (purple).

TADA!

 

[FuzzyDunlop]

I wouldn't say that. Most older V-8 balancers are 2-piece, and I've seen lots of bone-stock engines where the outer part of the balancer has slipped and the marks are off.

That said, I have no idea about the OP's motor. We also have no idea what state of assembly the motor is in, or WHY he needs to find TDC.

If he just needs to set/check timing or install a distributor, the dowel in the plug hole is good enough. If he's trying to set valve timing, he needs to be dead-on, and a more exact method is needed.

this. refer to my blog also found in this forum if youre interested.
http://forums.anandtech.com/showthread.php?t=2156092