Timing chain loose then tight. WTF? Help! Video up.
09-03-2011, 12:39 AM
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Timing chain loose then tight. WTF? Help! Video up. Ok, so I just finished installing my timing chain on my ls6 shortblock. Before moving on, I decided to turn the crank all the way around to make sure everything looked ok. I noticed the timing chain would be very tight at some points in the turn but would loosen up and be very slack at other points in the stroke. Seems like it was tightest from -4 to -8 and loosest around 6 or 8. I have a double roller timing chain and ls6 cam if that matters.
This was my first timing chain install, and it was more difficult than I imagined. The sprockets are lined up dot to 0 like in all the threads and books I've read and there was no difficulty turning the crank, but I just happened to notice the chain get a little more slack than I started with. My father thinks that either my camshaft or crankshaft is warped. I'm really hoping someone can tell me thats not true
This was my first timing chain install, and it was more difficult than I imagined. The sprockets are lined up dot to 0 like in all the threads and books I've read and there was no difficulty turning the crank, but I just happened to notice the chain get a little more slack than I started with. My father thinks that either my camshaft or crankshaft is warped. I'm really hoping someone can tell me thats not true
Last edited by SippiSpeedhawk; 09-03-2011 at 01:05 PM.
09-03-2011, 01:17 AM
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If you turned it with the rockers bolted down, it's just the valve springs pushing and pulling the cam. If you have the valvetrain loose, well then you might have some problems.
09-03-2011, 02:43 AM
#6
I would suspect the wear pattern on the cam or crank gears before i would even think something as far out as a cam or crank warping.
If the cam or crank were warped then you most likely would not be able to turn them by hand past their tight spot. As long as the crank and cam are just a slight warpage in the center of their length would muliply out many times over toward their ends and that would yield total lock up.
Take timing chain off and spin crank and cam individually and feel if there is any binding. It would be very apparent if either was warped enough to cause the craziness you are seeing at your timing chain.
I suspect that you are just seeing the rising and falling of the new timing chain on and off the leading and trailing edge of worn in teeth on one or both of your gears.
If the cam or crank were warped then you most likely would not be able to turn them by hand past their tight spot. As long as the crank and cam are just a slight warpage in the center of their length would muliply out many times over toward their ends and that would yield total lock up.
Take timing chain off and spin crank and cam individually and feel if there is any binding. It would be very apparent if either was warped enough to cause the craziness you are seeing at your timing chain.
I suspect that you are just seeing the rising and falling of the new timing chain on and off the leading and trailing edge of worn in teeth on one or both of your gears.
09-03-2011, 12:38 PM
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I would suspect the wear pattern on the cam or crank gears before i would even think something as far out as a cam or crank warping.
If the cam or crank were warped then you most likely would not be able to turn them by hand past their tight spot. As long as the crank and cam are just a slight warpage in the center of their length would muliply out many times over toward their ends and that would yield total lock up.
Take timing chain off and spin crank and cam individually and feel if there is any binding. It would be very apparent if either was warped enough to cause the craziness you are seeing at your timing chain.
I suspect that you are just seeing the rising and falling of the new timing chain on and off the leading and trailing edge of worn in teeth on one or both of your gears.
If the cam or crank were warped then you most likely would not be able to turn them by hand past their tight spot. As long as the crank and cam are just a slight warpage in the center of their length would muliply out many times over toward their ends and that would yield total lock up.
Take timing chain off and spin crank and cam individually and feel if there is any binding. It would be very apparent if either was warped enough to cause the craziness you are seeing at your timing chain.
I suspect that you are just seeing the rising and falling of the new timing chain on and off the leading and trailing edge of worn in teeth on one or both of your gears.
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09-03-2011, 03:18 PM
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take the chain off and bend each link individually, look for any stiff joints in the chain it will make a difference. i have also seen a cam gear that wasn't drilled exactly in the center and it did the same thing. attach a small piece of coathanger to one of the timing cover bolts and bend it so that it just comes to one of the teeth's points. then spin the gear and make sure that all of the teeth are the same relation to the pointer. a very small difference will make a big difference in chain tension. the one i saw that was bad was out of a bargain rebuild kit off the internet.
09-03-2011, 05:12 PM
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I just took the chain off and there are no stiff links. I also used the coat hanger idea on both the crank and cam sprockets and all the teeth appear to be the same difference from the pointer.
I did notice that the chain will wrap completely around the cam sprocket without any issues but I tried the same thing on the crank sprocket and the chain won't sit all the way down in between the teeth all the way around like it does on the cam sprocket. I tried it on the stock single row crank sprocket and the chain seats down between the teeth properly.
Is there a possibility that the teeth on the crank sprocket are uneven? If that were the issue, I could remedy it with a new timing set, no? It's a JP performance double roller timing set I got used from a member on here. I was told it had around 10k miles.
I did notice that the chain will wrap completely around the cam sprocket without any issues but I tried the same thing on the crank sprocket and the chain won't sit all the way down in between the teeth all the way around like it does on the cam sprocket. I tried it on the stock single row crank sprocket and the chain seats down between the teeth properly.
Is there a possibility that the teeth on the crank sprocket are uneven? If that were the issue, I could remedy it with a new timing set, no? It's a JP performance double roller timing set I got used from a member on here. I was told it had around 10k miles.
09-03-2011, 11:50 PM
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I believe I will be getting a single roller then. I have no need for the adjustability anyway; i see no reason to advance or retard my timing.
I just ordered the N-motion single roller set from SDPC. PN 7140. Will this suit my needs? I would have just gone with an LS2 replacement chain but I don't have a stock cam sprocket.
I just ordered the N-motion single roller set from SDPC. PN 7140. Will this suit my needs? I would have just gone with an LS2 replacement chain but I don't have a stock cam sprocket.
09-03-2011, 11:54 PM
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I imagine there is a reason the C5R and C6Rs use a single. Wish I had known this ahead of time. I just assumed the double was better because it was stronger. It seems like a lot of people run the doubles though.
09-04-2011, 07:25 AM
#20
Its completely normal........the chain you bought is NOT pre stertched to size. It will stretch evenly after you run the engine. If you took a calipers and carefully measured link to link you woooood find the links are all different lengths. Personally I woood buy a high quality pre stretched chain.
Tip If you really think the cam or gear is bent etc put a dial indicator on the outer edge just inside of the teeth of the cam gear and check for run out.
Tip If you really think the cam or gear is bent etc put a dial indicator on the outer edge just inside of the teeth of the cam gear and check for run out.