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Acceptable timing chain slack?

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Old Nov 25, 2017 | 07:07 PM
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Default Acceptable timing chain slack?

Hello!

I had to pull a switch-a-roo on my lower crank timing gear. The C5R chain now seems a little looser than with the other gear but doesn't seem to be "too" loose.

I would love some feedback!

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Old Nov 25, 2017 | 08:43 PM
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When the rollers get oil on them and the block expands from the thermal expansion the cam moves north and it’ll be tighter
Aluminum blocks are so different. Main bearing clearances are in the .0013”-.0018” range at room temp as the main bearing housings will expand and open those numbers up at operating temps.
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Old Nov 29, 2017 | 02:52 PM
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Looks good to me but also hard to tell because your cam is rocking a little letting all the slack go to one side and making the slack seem a bit exaggerated.

If you held the cam centered and checked slack you'd see a very small amount of movement on each side.

I agree with all that ARshale posted too.

However, what gear was there before? Did you change brands? Can you go back to the original brand, or even the original gear?
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Old Nov 29, 2017 | 03:21 PM
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Originally Posted by 00pooterSS
Looks good to me but also hard to tell because your cam is rocking a little letting all the slack go to one side and making the slack seem a bit exaggerated.

If you held the cam centered and checked slack you'd see a very small amount of movement on each side.

I agree with all that ARshale posted too.

However, what gear was there before? Did you change brands? Can you go back to the original brand, or even the original gear?
I think the cam only moved once near the end of the video. Your slack looks very much like the slack on the chain in my 6500 mile 6.0 (I just pulled it apart to install a cam). Mine might have had even a little more slack. When the crank is spinning the cam, the drivers side of the chain will be tight!
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Old Nov 29, 2017 | 03:48 PM
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Originally Posted by NEstyle
I think the cam only moved once near the end of the video. Your slack looks very much like the slack on the chain in my 6500 mile 6.0 (I just pulled it apart to install a cam). Mine might have had even a little more slack. When the crank is spinning the cam, the drivers side of the chain will be tight!
I agree but I bet it moves a little and we don't see it. There's no top end on it (lifters springs etc) to put pressure on the cam so it's free floating and the smallest pull on it will move it.

Edit: Watching carefully it moves each time he goes to the other side and I bet the video started with all slack to the side he's pulling on.

Either way, I say send it.
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Old Nov 29, 2017 | 04:43 PM
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If there are no springs pushing on the cam, then yes, it's definitely turning at least a little, which makes the situation even better.
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Old Nov 29, 2017 | 04:47 PM
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Originally Posted by NEstyle
If there are no springs pushing on the cam, then yes, it's definitely turning at least a little, which makes the situation even better.
My thoughts exactly.
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Old Nov 29, 2017 | 09:36 PM
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Run it.
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Old Nov 30, 2017 | 10:37 AM
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Default Cam Timing + AL Block Growth

Hi All, this is "great" tech about timing chain tension AND NO "tech" with reference to the effects of this tension on Cam Timing, no report ?

I have that data.

Lance
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Old Nov 30, 2017 | 11:35 PM
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Originally Posted by Pantera EFI
Hi All, this is "great" tech about timing chain tension AND NO "tech" with reference to the effects of this tension on Cam Timing, no report ?

I have that data.

Lance
I remember checking the degrees (installed) of an all aluminum 18 degree headed endurance engine back in 2000. Had Weld Tech ported GM castings 12:1. 4.155” x 3.25” and and ISKY 258/264 solid roller with Ti valves. Made like 735 horse
After lashing the valves the cam retarded 1.25 degrees from originally checked
This was with a belt drive however the impact of the stiff *** valve springs made a difference
Basically learned why to use a crank trigger AND belt drive front distributor.
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Old Dec 1, 2017 | 10:24 AM
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Default C-DBug/TW-DBug

Hi AR, yes one reason, NOT the important reason.

The GM58x (60-2) TW has much information when decode is correct.
The Crankshaft Acceleration can be recorded.
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