ok i have a 89 pontac firebird 305 tbi and i need to no how can `i tell when my car is top dead center and i really wont to no the easyes way

 

Here is an easy way to find TDC.

• Find the timing mark on the harmonic balancer. You may need to clean the harmonic balancer to find it.
• Remove the number one spark plug. This is somewhat optional. If you loosen the spark plug so that air can escape from the cylinder, then you can hear the air bleed past the threads when the number one cylinder is coming up to the compression stroke. If you decide to completely remove the spark plug you can put a finger over ( not in ) the spark plug hole. This will enable you to feel the air being forced out of the cylinder as the piston compresses it. Using a finger to cap the hole does not work well when the motor is hot though.
• If you have a remote starter button, connect it to the starter terminals. One clamp goes on the starter solenoid's small wire terminal closest to the motor, the other clamps to the battery cable terminal on the starter solenoid. Use the starter button to crank the engine over in short bursts.
• If you do not have a remote starter button, use a small flat blade screwdriver to short the 2 terminals together. When you have the starter right in front of you, it can be rather loud so you will need to pay attention to the sound of the compressed air escaping from cylinder number one.
• If you use the screw driver method and completely remove the spark plug, you may need someone's assistance to either short out the solenoid or put their finger over the spark plug hole.
• Once you hear the air escaping this means the piston is coming up to tdc. The air does not escapse quickly, it tends to bleed out if the spark plug is still in the hole. Stop turning it over.
• Locate the timing mark on the harmonic balancer. You may need to crank the engine a few times to get it to come around to the timing mark on the timing tab. Don't expect it to stop at tdc, you will be lucky if that happens. You may need to turn the harmonic balancer manually towards or back to tdc.
• Bring the timing mark on the harmonic balancer in line with the 0 degree mark (tdc) on the timing tab. You will notice several lines on the timing tab. The thickest line is 0 degrees and each line represents 2 degrees. Clockwise ( looking at the engine ) of this line is past tdc which would mean your timing is retarded, and counter clockwise is before tdc which would mean your timing is advanced. Note how the picture of the timing tab on this 283 chevy small block denotes tdc with a "0" for zero degress advance, and an "A" so you know which side of zero is advance.

 

That's all providing your timing marks are accurate.

It all depends why you're trying to find TDC.

The most exact way is by using a degree wheel and a piston stop but if all you're doing is adjusting valves then that's an overkill way of doing it. A piston can stay at the top of the cylinder for a few degrees of crank rotation (dwell). Using the timing marks will get you close since timing marks may not be 100% accurate. Using a degree wheel and a piston stop can get you at 100% TDC. If the timing marks line up exactly at that point then you're doing good.

If you have an adjustable timing pointer then a degree wheel needs to be used to position the pointer.

 

don't really need a degree wheel either

using a piston stop, turn it over until it...stops. mark where it stopped. now turn the motor over going the other direction (backwards)...until it stops. mark that location. then ur mid point between the 2 is ur tdc. set your timing pointer and enjoy