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top dead centre

Posted: Wed Apr 05, 2006 6:40 pm
by hillbilly
If I remove number 1 spark plug , is t.d.c the position of the piston
when at the top of the bore?? 5l holden motor.

cheers.

Posted: Wed Apr 05, 2006 6:51 pm
by jeep97tj
Yep your right, It will be at the top, What are u doing? If u are seting up the spark timing make sure both valves are closed aswell.

Posted: Wed Apr 05, 2006 7:13 pm
by 360 scout
be aware that the piston will be at TDC for several degrees of crankshaft rotation so not real acurate if referencing off the crank there are several other methods which are more accurate .

Posted: Wed Apr 05, 2006 7:22 pm
by hillbilly
Tried using a dial gauge, and when the piston hit top , figured that was it. Did not keep turning the crank when the gauge stopped climbing. Is this right?
From there, is it just adjusting the dizzy to get the correct timing?






.

Posted: Wed Apr 05, 2006 7:26 pm
by F'n_Rover
hillbilly wrote:Tried using a dial gauge, and when the piston hit top , figured that was it. Did not keep turning the crank when the gauge stopped climbing. Is this right?
From there, is it just adjusting the dizzy to get the correct timing?






.
Fark, if you just want to find TDC for static timing - just stick your finger in the hole and wait for the pressure to stop. No need for super accuracy.

Posted: Wed Apr 05, 2006 8:21 pm
by jeep97tj
hillbilly wrote:Tried using a dial gauge, and when the piston hit top , figured that was it. Did not keep turning the crank when the gauge stopped climbing. Is this right?
From there, is it just adjusting the dizzy to get the correct timing?
.
It will be close enough to start, but yer a screw driver down the plug hole would of been just as good. U will still have to adj it from there though with a timing light. Did u make sure u were at the top of the compression stroke and not the top of the inlet or exhaust stroke? U have to read the cam when setting up the dizzy other wise it will just back fire and not start.

Posted: Wed Apr 05, 2006 8:40 pm
by hillbilly
I have to read the cam when setting up the dizzy???
I don't understand.
Please explain.
Cheers.

Posted: Wed Apr 05, 2006 9:38 pm
by F'n_Rover
hillbilly wrote:I have to read the cam when setting up the dizzy???
I don't understand.
Please explain.
Cheers.
You want the spark to happen on the compression cycle not the exhaust cycle. Just do the finger thing, don't have to worry about the cam then.