I have a 2006 2.4 hhr that I just rebuilt the motor on. I triple check the timing marks on both the balance shafts and the camshafts, and they all line up. Balance shafts, exhaust at six o'clock, intake at 12 o'clock, crankshaft sprocket at six. The camshaft sprocket exhaust at 10 o'clock and intake at 2 o'clock with the crankshaft sprocket at 5 o'clock. When i try to start it, the motor sound like it does not have any compression. I took the valve cover off and turned the motor over my hand. I notice that as soon as the intake valve on number one cylinder opens and then closes that the exhaust valve begins to open. I know that the exhaust valve should not open until after the combustion or power stroke takes place. It seems to me that one of the camshaft are 180 off, but if I turn it, the chain links will not line up. any suggestions.

 

It is a 4 stroke engine , TDC in #1 , crank key way at 12 o’clock , the camshafts notches should be at intake 5 o’clock , exhaust 7 o’clock

 

That might be the correct positions if you don't have the chain on.
Here is the placement of the marked links.


Step 1

Step 2

Step 3

 

I will check and see if the camshaft are in that position. Oh by the way is there a way to know the different between the intake and exhaust camshaft, they look the same to me

 

Yes, I had them lined up exactly like your pictures with chain on.

 

You just rebuilt the motor. Did you buy a rebuilt head?

 

I've never seen it like that before. I've only seen 10 exhaust and 2 intake.

 

No, I did a valve job on the head though. but the block was replaced

 

Oldblue's illustration is from a different article. Not the chain article. Mine are correct for replacing the chain; step 1 is the crankshaft, step 2 is the intake, step 3 is the exhaust (the exhaust gear should be off installed with the chain)

The exhaust is the one closest to the exhaust manifold. I think the 2.4L has 2 different shafts 12578515 for exhaust and 12578511 for intake.

DO NOT TURN THE CRANKSHAFT COUNTER-CLOCKWISE.

Once you turn the crankshaft you need to take it all apart and start over; it takes a lot of revolutions to get back to lined up.

 

From what I can tell,
your exhaust cam should be GM pn 12578512

Your intake cam should be GM pn 12578511

Not sure if those are cast into the camshafts or not. Worth a look.