Timing mark- intake or power stroke at TDC?
02-19-2017, 10:30 AM
#1
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Join Date: 02-19-2017
Location: Florida
Posts: 5
Timing mark- intake or power stroke at TDC?
So I'm helping a friend do his timing chain on his 2.4L ecotech HHR. I have a question regarding setting the cams...
Everything I read is to have your #1 piston at TDC on the transition between compression stroke (piston going up) going into power stroke (piston going down.) The phase of the stroke is determined by your cams.
OK the guides I've read is to have your intake cam gear (front cam) diamond at around the 2 o'clock position and the rear cam gear diamond (exhaust cam) at around the 10 o'clock position. I've got everything lined up however this is my question...
The intake cam in this configuration on startup will begin the spin clockwise. How the intake cam is current sitting with the diamond at 2oclock immediately will begin to open the intake valves thus indicating a "intake stroke". I'm confused as all guides say set engine at TDC going into "power stroke" but the cam lobe at correct timing marks is going into intake stroke.
Everything I read is to have your #1 piston at TDC on the transition between compression stroke (piston going up) going into power stroke (piston going down.) The phase of the stroke is determined by your cams.
OK the guides I've read is to have your intake cam gear (front cam) diamond at around the 2 o'clock position and the rear cam gear diamond (exhaust cam) at around the 10 o'clock position. I've got everything lined up however this is my question...
The intake cam in this configuration on startup will begin the spin clockwise. How the intake cam is current sitting with the diamond at 2oclock immediately will begin to open the intake valves thus indicating a "intake stroke". I'm confused as all guides say set engine at TDC going into "power stroke" but the cam lobe at correct timing marks is going into intake stroke.
02-19-2017, 10:46 AM
#2
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Join Date: 02-19-2017
Location: Florida
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That would make sense. I was going crazy reading a guide to set at TDC entering powerstroke then looking at the cam lobes that indicates it's intake stroke.
02-19-2017, 10:51 AM
#3
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No, I think I was incorrect, but here is the real deal. Intake at 2, exhaust at 10. But you've left out an important piece of the puzzle. The mark on the crank, it needs to be at approximately 5 o'clock position(closer to 4:30).
02-19-2017, 10:57 AM
#4
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Join Date: 02-19-2017
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Yeah crank notch is at 12oclock and timing mark is at 5oclock.
02-19-2017, 11:42 AM
#7
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Here is the procedure that donbrew shared in another thread.
Timing Chain Service Procedures GM 2.2L L61 Ecotec, Camshaft Sprocket
Timing Chain Service Procedures GM 2.2L L61 Ecotec, Camshaft Sprocket
02-19-2017, 12:40 PM
#9
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Join Date: 02-19-2017
Location: Florida
Posts: 5
Basically, if the 3 marks on the chain match the 3 reference points it is right. That is why there are 3 not 2.
You don't have to worry about cycles or TDC.
Attachment 20907 Attachment 20908
You don't have to worry about cycles or TDC.
Attachment 20907 Attachment 20908
OK thanks I thought so too. I just picked up the plastic timing chain guide (it was broken in 3 pieces ...wow!) About to put everything back together. Wish me luck!
02-19-2017, 12:45 PM
#10
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Which part is different? I have seen a 2.4 illustration with the cam marks at really odd spots.
This what Mitchell says for the 2.4L, I have only done 2.2L. I don't know if this is correct.
Later on they say this, first pink link goes to crank mark last pink link goes to exhaust mark.
Maybe I am confusing the marks on the actuator Vs. the marks on the sprockets. Now I'm getting really confused the 2009 2.2 and 2.4 both have VVT and are the same procedure (at 5 and 7).
HOWEVER; note intake is a diamond exhaust is a triangle in post #5.
This what Mitchell says for the 2.4L, I have only done 2.2L. I don't know if this is correct.
Later on they say this, first pink link goes to crank mark last pink link goes to exhaust mark.
Maybe I am confusing the marks on the actuator Vs. the marks on the sprockets. Now I'm getting really confused the 2009 2.2 and 2.4 both have VVT and are the same procedure (at 5 and 7).
HOWEVER; note intake is a diamond exhaust is a triangle in post #5.