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Thread: is this correct timing setup?

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Posts: 31-40 of 53
2010-10-10 22:29:56
#31
Originally Posted by Autech
Pull tensioner out, pull cam gears off. Move crank to TDC at 1.
I would be so worried about pistons hitting valves.
Is that an unfounded worry?
2010-10-11 02:27:57
#32
You would know if the pistons were hitting the valves after a few turns of the motor. Note he said the spin the motor 4 times.
2010-10-11 02:32:48
#33
No, I would be worried that if I removed the cam sprockets and turned the motor to TDC there would be a huge chance of pistons hitting valves since the valves are no longer mechanically connected to the rotating assembly. You could easily bend a valve trying to bring the bottom end to TDC depending on the position of the cams.

No?
2010-10-11 02:40:25
#34
I think it should only be for fine adjustment. Safer to do it with the cams still in but if you're not really careful the crank may move slightly when you remove the tensioner and cam sprockets. Definately don't go spinning the crank with the cams disconnected!!
2010-10-11 02:43:30
#35
Yah that's what I was thinking. Dangerous advice.
2010-10-11 02:45:22
#36
Originally Posted by BenFenner
No, I would be worried that if I removed the cam sprockets and turned the motor to TDC there would be a huge chance of pistons hitting valves since the valves are no longer mechanically connected to the rotating assembly. You could easily bend a valve trying to bring the bottom end to TDC depending on the position of the cams.

No?


You would have to Hercules to bend the valves by spinning the motor by hand. Just to feel safe I would just take the cams out of the motor along with the cam gears and retime the motor.
2010-10-11 02:57:29
#37
Originally Posted by BenFenner
Yah that's what I was thinking. Dangerous advice.


I do this day in day out.

I should clarify, this is from when he already has everything within a tooth of each other from his current position!

Sometimes, if setup lazily, or rushed, you can accidentally leave a lack of tension on the exhaust cam - and as you mock rotate the motor it will jump and so will the inlet. The timing chain wont catch it, and you will never know if you dont double or triple check. This is why i rotate the motor 4 cycles to ensure the tensioner settles and releases far enough.
2010-10-11 12:34:48
#38
I've read a few times on the Forum that there is not enough room for the chain to slip a tooth on the crank gear. Is this the conventional wisdom? Or is it something to be concerned about?
2010-10-11 13:04:18
#39
Originally Posted by billc
I've read a few times on the Forum that there is not enough room for the chain to slip a tooth on the crank gear. Is this the conventional wisdom? Or is it something to be concerned about?


For your FWD engines generally its not, however if you put enough stress on the chain you can accidentally loop it and it can snap the dowel on the back of the oil pump casting in early generation engines.

When you go to late generation VE and RR motors they have a long semi circle casting following the chain which makes it impossible to happen.

ON ALL RWD motors it can happen however!

On all motors, if tension is left either side of the exhaust cam - it cam jump if your not careful!
2010-10-11 13:05:42
#40
It's hard to do, but it's certainly possible to skip a tooth on the crank sprocket.

Edit: Autech beat me to it.
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