How to determine TDC?

99SE-L · 10-14-2003, 08:04 PM

How can I determine TDC? I can't use the cam sprockets because they are out of synch with the pistons. I need to reset the cam timing.

Harris · 10-14-2003, 08:11 PM

TDC is the top most position the piston #1 will reach during compression stroke, IIRC.

Slartibartfast · 10-14-2003, 08:32 PM

Correct, and you'll know it's the compression stroke because both and exhaust valves are closed.

99SE-L · 10-14-2003, 09:08 PM

the timing chain was not hooked up when I spin them so everything is off. Can I manually set the position of the valves(cams) and just rotate until the piston is at the top and it will be automatically set to the compression stroke?

AntonioG · 10-14-2003, 10:24 PM

You can use your crank pulley TDC mark and line it up with the timing indicator. Get #1 to 'look' like both valves are closed (cam lobes pointing away from each other) and match up 0 on the pulley with the timing indicator.

99SE-L · 10-15-2003, 01:52 PM

Yeah that's what I did. Took off both the exhaust and intake cam shafts to make sure the piston won't hit against the valves and rotated the crank till the piston is at max. Figured it out by eyeballing the crank pulley mark and a screw driver in the #1 cylinder so for sure it's at max. Put back on the cam shafts with the #1 lobes on the int and exh facing away from each other. I had people telling me I might be 180deg off but I figured this has to be right since the exhaust lobe is about to turn down(clock wise) to open up at the end of the power stroke and the intake remains closed.

I then aligned two dark colored chains with the circular marks on the int and exh sprockets. This has to be right since there are 20pins in between. I then used a method to count 56 pins between the intake marking and crank marking and found out the chain is where it's supposed to be on the crank so for sure it did not skip on the crank.

Now I'm positive the timing is right. Tried to start the car. It cranks but won't start. The only thing left to check now is the ignition timing might be off 180*. Going to take off valve cover again and rotate to TDC and make sure the rotor on the distributor is pointing at spark plug 1. If everything is right, then I can't figure what might have gone wrong.

99SE-L · 10-15-2003, 04:29 PM

I popped off the valve cover and found out the timing is off again! I gave it some more thought and figured that I was wrong about being able to determine which link was on the crank shaft mating mark. I know the manual shows it needs to be 56pins between the intake and crank and 40pins between the crank and exhaust mating marks. I just realize there is no way to know this, hence there is no way to get the timing right again without removing the timing chain cover. Simply setting the piston and cams to top dead center and mating the black links to the intake and exhaust marks will not guarantee you that you the 56 and 40 pins. I've tried that 3 times. If you don't have the correct number of pins between the mating marks, after a few rotations, the timing will be totally off. Correct me if I'm wrong.

99SE-L · 10-15-2003, 10:42 PM

got it fixed....... whewww..

chris13bsr20 · 10-16-2003, 02:28 PM

Quote:

Originally Posted by 99SE-L

got it fixed....... whewww..

So how's it running now? I've been following this for days with my fingers crossed for ya... I was lucky to have my intake cam install go smooth I guess.

99SE-L · 10-16-2003, 11:40 PM

Runs fine. Feels the same as ** though =(
All that work to gain like 3hp. But I do think I have a vacuum leak some where which is draining me of power because my car isn't running so well even ** the cam install.