[Z'mnypit]

Originally Posted by IHateHacks

TDC is when the notch on the crank pulley lines up with the 0 degree mark on the lower timing belt cover. Every time the crank pulley notch lines up with the 0 degree mark, the no.1 piston is on TDC.

Since the head is off the block, there is only one TDC. But when you put the head on, there are 2 TDC's. It's the same with any engine OHC, DOHC or OHV. One is on the compression stroke and the valves are closed and the cam gear matchmarks line up with the notches on the inner timing belt cover. The other is on the exhaust stroke with the exhaust valves open and the cam gear matchmarks are 180 degrees to the notches on the inner timing belt cover. Every 4 stroke engine has 2 TDC's, even your OHV "cam in the block" camaro. For every 2 revolutions of the crank, the cam(s) revolve once.

So, before you place the head on, make sure the crank pulley notch lines up with the 0 on the lower timing belt cover. Then when you install the timing belt you determine what TDC it is on. With the cam gear marks lined up with the notches in the inner timing belt cover you are on the correct TDC. I know it sounds confusing but it really isn't. Did you build the motor in your camaro that you list in your sig? If you did, then when you put the timing chain on you did the same thing, crank gear was lined up with the cam gear mark. Then, if you spun the crank 1 revolution, the cam gear no longer lined up, yet the no.1 piston was at TDC again. Spin the crank 1 move revolution and the gears lined up again.

You'll see what I mean when you put the timing belt on. Spin the crank one revolution from the 0 degree mark and you'll see the cams only moved 180 degrees yet you come back to the 0 mark on the crank which means the piston is on TDC, but on the exhaust stroke.

As long as the crank pulley notch is lined up with the 0 mark on the lower timing belt cover you are good to go. Then when the head is on, just line up the cam gears with their notches in the inner timing belt cover, install the timing belt and you are straight. Then its time to install the CPS (Cam Position Sensor). But we will cross that bridge when we get there.

Thats what I was thinking. But the repair manual worded it a little differently. I understand what you mean!

Yep, I built the motor in the camaro. The cam sprocket had a dot and the crank sprocket had a dot. You line them up 6 oclock and 12 o clock and your set. Any timing changes that need to be made I do with my laptop (HPTuners). There is no CPS that has to be moved.

Thanks man, thats what I needed!