Finding TDC
03-25-2004, 09:27 AM
#1
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Finding TDC How many revolutions of the engine does it take to find TDC on any given cylinder? I must have turned my engine over 20-25 times. I only had the passenger side valve cover off but not once, were each the exhaust and intake valves fully down on any of those cylinders. 
03-25-2004, 09:58 AM
#3
First off start by looking at the number one cylinder it is the first one one the drivers side. You can remove the valve cover and then you can turn the motor over slowly and watch for both of the valves to be at the top. Think of how your motor functions it sucks(down) in some air and fuel and then it comes to the top on the compression stroke(up also TDC) and then it fires(down) and then the exhaust valve opens to push the burn fuel air out(up). That is where the tern four stoke comes from. Another way if you are still not sure is to remove the spark plug and hold your finger over the opening and slowly turn the motor over and when it blows your finger off of the hole it is at or very near TDC. Good luck on what ever you are doing just take your time pay attention to every thing that you take off and make sure it looks the same when repalcing it and tourque every thing down to spec.
03-25-2004, 10:40 AM
#5
LS1's are real pinicky,once u get both rockers to go loose it still might take a smidge to get both valves closed.
I use a big breaker bar on the crank bolt.
Then u can put air into the cyl holding the bar and see if the cyl hold air,At that point I remove the rockers so I know the valves cant be open.Thats as close to TDC as you'll get without a degree'd balacer or the cam cover off.
This is where u do your leakdown test.
I use a big breaker bar on the crank bolt.
Then u can put air into the cyl holding the bar and see if the cyl hold air,At that point I remove the rockers so I know the valves cant be open.Thats as close to TDC as you'll get without a degree'd balacer or the cam cover off.
This is where u do your leakdown test.
03-25-2004, 01:41 PM
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*&@#$)*&# I thought it was when both rockers were at the top. I had 2 different people tell me when they were both down. *&#^$*(#@^
I tore my car apart last night to adjust them and put it back together because both valves were never open.
It makes perfect sense (what you guys are saying) but it was to the contrary of what two others said. Thanks for your help.
I tore my car apart last night to adjust them and put it back together because both valves were never open.
It makes perfect sense (what you guys are saying) but it was to the contrary of what two others said. Thanks for your help.
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03-25-2004, 01:51 PM
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Nope. It should still be firmly seated even when the valve is completely closed. Some go for zero lash, some do a little preload. I'd try taking it to zero lash to begin with and adjust from there.
