(ENGINE) How do I find TDC on my engine?
 

I bought a timing light to work on my '85 (12A), hooked it up to the leading plug on the number one rotor as the Haynes manual directed, and proceeded to check the timing. The car runs fine, but the timing is way off from the timing marks. The marks are so far off, that no adjustment of leading or trailing timing can bring them anywhere close to the timing pin. I am thinking that they are off by at least one cycle (more than 100 degrees).

Just to be sure I didn't hook it to the wrong plug wire, I tried the other rotor as well. It was also no where close.

When I hooked the timing light to the leading coil to distributor wire, however, the timing marks were within a few degrees of the pin.

What is going on? I am trying to install a CD ignition, but if the timing marks are not working correctly with the stock ignition, the installation will be very difficult.

Do you know if your TDC lined up correctly?

Make sure you have it lined up at TDC first. If the motor has never been torn down, you can do that by rotating the crank pully until the yellow notch is lined up with the timing pin on the front cover.

If the engine has been opened up, then the crank pully could have been put on wrong. Take off the side inspection plate (behind the exhaust manifold) and shine a flashlight in. Rotate the crank pulley until you see the flat side of the flywheel and line that up with the flat side of the engine, where the intake and exhaust are. Now look at your pulley. If you do not see the timing marks, remove the pulley and line it up. You are now at top dead center.

Take the dizzy out. Right where the gear is, you should see a dot. Whirl the dizzy gear around until it is lined up with the notch on the bottom of the shaft. Insert this into the motor, being very careful not to miss it by a tooth. Timing can now be set :)


Inspection plate:
http://i26.tinypic.com/2z6s4jl.jpg

Leading dot and timing pin:
http://i28.tinypic.com/binrdk.jpg

Dizzy:
http://i29.tinypic.com/156y9tt.jpg

If you decide your pulley is installed incorrectly read these before removing the pulley.
http://www.mazdatrix.com/faq/pulley.htm
http://fm.no-ip.com/btraps.html#PULLEYS
Easiest solution is to find top dead center and remark the front pulley.

When Stu says to remove the pulley, he means remove the 4 10mm bolts and rotate into the correct position. As long as you don't remove the big bolt, you don't have to worry about the mazdatrix info, but it is good stuff to keep in mind in case you do have to remove the big bolt sometime in the future.

Fudge, I don't remember if I lined up my Dizzy-ish thing for my 6-port...

What a great thread, I book marked it so when I go to stick my dizzy back in I don't F it up, thanx.