Could this be right?? (Thermostat Nightmare Cont) - EDIT THE EXHAUST VALVE IS OPEN AT TDC
01-23-2005, 10:50 AM
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Could this be right?? (Thermostat Nightmare Cont) - EDIT THE EXHAUST VALVE IS OPEN AT TDC
We pulled the valve covers off this morning in the process of pulling the heads, replacing valves, etc. Prior to pulling heads we went to set the engine at TDC and noticed that the exhaust valve on cylinder one is open at TDC. Now I'm no expert but that doesn't seem right!
Is there a way to check exact cam timing? What in THE hell is going on here?
Check the pics. Need expert advice ASAP. Thanks.
<img src="http://pictureposter.audiworld.com/30922/valve_alignment_at_tdc.jpg">
<img src="http://pictureposter.audiworld.com/30922/crank_alignment.jpg">
<img src="http://pictureposter.audiworld.com/30922/cam_alignment.jpg">
<img src="http://pictureposter.audiworld.com/30922/passenger_side.jpg">
Is there a way to check exact cam timing? What in THE hell is going on here?
Check the pics. Need expert advice ASAP. Thanks.
<img src="http://pictureposter.audiworld.com/30922/valve_alignment_at_tdc.jpg">
<img src="http://pictureposter.audiworld.com/30922/crank_alignment.jpg">
<img src="http://pictureposter.audiworld.com/30922/cam_alignment.jpg">
<img src="http://pictureposter.audiworld.com/30922/passenger_side.jpg">
01-23-2005, 10:57 AM
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are you sure your at TDC
You have a 4 stroke motor. For every one turn of the crank the cam gear needs to turn twice.
Pull the spark plug and stick a screw driver in there and watch the piston go up and down.
Pull the spark plug and stick a screw driver in there and watch the piston go up and down.
01-23-2005, 11:13 AM
#4
TDC= Top Dead Center, of the piston...
Very difficult to say, for certain, at this point of your timing?
We do not "know" where it was before you began, and can only assume it was right because the engine ran without issue(?)
Then, somehow, during the thermostat R&R your timing got messed up, and to what extent we also do not know for certain.
With that said, looking at the pictures posted, your cam sprockets are good because the larger of the 2 holes is inboard. Also the crank pulley looks good. With this, I would add, the placement of the timing marks, might not be TDC of the #1 piston(?)
It was several years ago when I did my heads, and cannot say for certain the #1 intake valve is suppose to be open...
Judging from your pic's, the timing looks correct.
We do not "know" where it was before you began, and can only assume it was right because the engine ran without issue(?)
Then, somehow, during the thermostat R&R your timing got messed up, and to what extent we also do not know for certain.
With that said, looking at the pictures posted, your cam sprockets are good because the larger of the 2 holes is inboard. Also the crank pulley looks good. With this, I would add, the placement of the timing marks, might not be TDC of the #1 piston(?)
It was several years ago when I did my heads, and cannot say for certain the #1 intake valve is suppose to be open...
Judging from your pic's, the timing looks correct.
01-23-2005, 11:19 AM
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if you don't understand what I am saying maybe you should put it back together and leave it alone..
Take that the nice way please.
TDC is when the piston reaches the top of the engine block.
Intake vavle opens... and air is pulled into the engine on the down stroke...and then compressed and then spark happens and combusted and the piston travels down.
maybe you should do a search on "how things work" etc.
If you turn the motor by hand you can watch the piston travel up and down with a screw driver or a long tool that fits in the spark plug hole. I am not familar with the 12v motors but there are timing marks for lining up TDC. Just because the cam gear is on TDC doesn't mean it's at the TDC.
Think about it for a while. It it was running right, and you haven't touched the belts than it's probably fine.
Maybe some one else can chime into this because I stick with my 5 cylinder motors.
TDC is when the piston reaches the top of the engine block.
Intake vavle opens... and air is pulled into the engine on the down stroke...and then compressed and then spark happens and combusted and the piston travels down.
maybe you should do a search on "how things work" etc.
If you turn the motor by hand you can watch the piston travel up and down with a screw driver or a long tool that fits in the spark plug hole. I am not familar with the 12v motors but there are timing marks for lining up TDC. Just because the cam gear is on TDC doesn't mean it's at the TDC.
Think about it for a while. It it was running right, and you haven't touched the belts than it's probably fine.
Maybe some one else can chime into this because I stick with my 5 cylinder motors.
