Top Dead Center

renaissance man · #1 (**permalink**) 02-04-2002, 07:48 AM

What is the easiest most accurate way to determine if you are at TDC to set your distributor? I'm a one man crew so don't have a second set of eyes or hands.

CobraEd · #2 (**permalink**) 02-04-2002, 07:53 AM

Jegs sells a TDC tool for about $9. It screws into the sparkplug hole of your #1 cylinder. You turn the engine in one direction *BY HAND* until the piston hits the tool. Mark the harmonic damper at that spot. Then turn the engine the other way *BY HAND* untill it hits again. Mark the damper at that spot. Then find the spot on the dampner that is exactly between your two marks, and that is top dead center!!!

You can thank me later

Ed

Cobra20646 · #3 (**permalink**) 02-04-2002, 02:35 PM

Dave,
Ed's suggestion is right on the money..... but if your indexing the distributor, make sure you find TDC on the compression stroke.
- Jim -

Rick Parker · #4 (**permalink**) 02-04-2002, 07:56 PM

Pop the passenger side valve cover and off rotate crank (preferably by hand with breaker bar on front crank damper retaining bolt) until both valves are closed. If you run solid lifter cam each pushrod will spin in your fingers at this time. Then check timing marks (should be close to "0" now) and continue to rotate crank until the timing marks line up at "0" degrees. Put distributor in and align rotor to #1 plug tower. The alternative is to pull # 1 plug and crank engine with starter while holding finger in sparkplug hole, the compression will pop it out when it nears TDC. The first method is a little more controlled, the second requires an assistant or a method of cranking starter while your
finger is over the sparkplug hole. After a little practice the second method is quicker too.
Rick

ERA535 · #5 (**permalink**) 02-04-2002, 09:00 PM

Put a thin screwdriver into the spark plug hole and s-l-o-w-l-y turn the engine over with a breaker bar until you feel the piston come to it's highest point....this isn't the scientific way but is fast and easy. After the piston comes to its highest point you will notice that you can turn the engine a few degrees each way and the piston won't go up or down even though you are turning the engine...this is called dwell -- try to guess the spot halfway between the piston going up or down THAT will be damned close to TDC.

renaissance man · #6 (**permalink**) 02-06-2002, 12:33 PM

These are all great but, as a one man operation non seems practical? No way to turn the engine by hand. The March pulley system covers over the bolt on the crank. Can't loosen the pulley and turn the crank "literally" by hand.

Any other guesses? Too bad I can' just line up the distributor with another piston that is in the TDC position? It looks as if the #1 cylinder in on the "Intake" as the rocker is about a 1/4" lower than the rest of the rockers.

Leo · #7 (**permalink**) 02-06-2002, 01:18 PM

Pull all your spark plugs out. You may then be able to turn it by hand. If not, with the plugs still out, put trans in a high gear (3rd of 4th) and push the car a little until you get the pully where you want it.

scottj · #8 (**permalink**) 02-06-2002, 01:20 PM

Dave,

You can find the top of the #1 compression stroke by bumping the engine over with the #1 sparkplug threaded in a couple of turns. When you hear air whoosh past the threads your coming up on #1.

Scott

flipscobra · #9 (**permalink**) 06-20-2007, 02:55 PM

Easy way is plug spark hole with your finger, when it blows your finger out you will be right at TDC on the compression stroke.

BossCER · #10 (**permalink**) 06-20-2007, 03:33 PM

You can find not a single person in your area to turn a key for you?? I thought they were friendly in the South

Excaliber · #11 (**permalink**) 06-20-2007, 04:08 PM

There is no easy way! Cranking with the starter or a remote starter switch wired to the solenoid will only get you 'close'. Only ONE way to establish true TDC, gotta turn the engine by hand, period. With all the spark plugs out this MAY actually be possible by literally turning the belt/pullies by hand.

392cobra · #12 (**permalink**) 06-20-2007, 04:17 PM

Dave,the guy who started this thread,posted this in 02/02.He sold his Cobra several years ago.

I agree though,has to be done by hand.

AC Cobra · #13 (**permalink**) 06-20-2007, 04:42 PM

That just goes to show you. You've got to read he fine print. I read all the way down to 392cobra's comment before realizing the thread started in February 2002. But now I can find TDC with all these comments. Thanks guys.

Michael C Henry · #14 (**permalink**) 07-05-2007, 10:42 AM

Once you have decided where TDC actually is, you'll have a pointo start from. In my case turning it over with a long 1/2" ratchetIs slow do to not much room to get a long through. so I wouldn't hear that woush past the plug threads. I do have an air compressor and a rubber tipped blow gun. I'll blow in the #1 hole to confirm that I'm on the compression stroke. Note; do not seal the blow gun off to head or the pressure may cause the crank to rotate from the spto you went through all this effort to arrive at. You're just listening for the sound fo air comming out exhaust ot intake. You don't want that. You want both intake and exhaust valves closed and air coming back out the spark plug hole.
I have broken the distributer drive pin twice. Both times at home. Starting with cold oil and too much throttle. No other damage . It takes about an hour to get it repaired and running again.

Clois Harlan · #15 (**permalink**) 07-06-2007, 05:49 AM

Go to harbour Freight and buy a remote starter for $5 (hooks up to your solinoid - one lead on the battery cable that bolts to the side and goes to the starter and one lead on the #10 stud in the front). Remove your spark plug and stick your finger in the hole. take your coil wire off and then press your remoter starter until the piston arrives at TDC on the compression stroke.

tcrist · #16 (**permalink**) 07-06-2007, 05:57 AM

I might be better just to stick you thumb over the hole. Depending on how small your fingers are, you might get pinched and that would hurt like H__L.

Terry

rdorman · #17 (**permalink**) 07-06-2007, 06:50 AM

Quote:

Originally Posted by renaissance man

These are all great but, as a one man operation non seems practical? No way to turn the engine by hand. The March pulley system covers over the bolt on the crank. Can't loosen the pulley and turn the crank "literally" by hand.

Any other guesses? Too bad I can' just line up the distributor with another piston that is in the TDC position? It looks as if the #1 cylinder in on the "Intake" as the rocker is about a 1/4" lower than the rest of the rockers.

Take the cover/pulley off. Listen to CobraEd and be sure you are coming up on compression.

trularin · #18 (**permalink**) 07-06-2007, 07:33 AM

Yes, and after you get out of the hospital with a splint on your finger, you will know where TDC is.

May I suggest removing the coil wire before you start this proceedure. Additionally, if you put a finger in the hole, do it only a very small distance in, feel for the top of the piston.

Excaliber · #19 (**permalink**) 07-06-2007, 09:09 AM

Hold the coil wire with one hand and your finger in the piston hole, then have your wife hit the key.

Alternative method: Here, pull my finger!

Sal Gerace · #20 (**permalink**) 07-06-2007, 09:32 AM

Neutral, Neutral , Neutral, then! Take off the coil wire. Take out number one spark plug. Tap the engine around using a screwdriver to jump the two starter solinoid terminals (from left to right on the solinoid the first two). As you are tapping around the engine keep your finger on the plug hole until you feel the compression of air pushing your thumb off the hole. As you are doing this look at the balancer and you should see TDC coming up on the balancer. Now you know you are on the right stroke. Once you are close you can bring it to perfection with a 1/2" drive breaker and socket on the balancer bolt. Don't forget that the engine is going to fire at the initial timimg that you set in so you may want to bring you pointer to that mark before setting in the distributor or use it as a referance once the distributor is in, Sal.