04-07-10, 06:57 PM
i have a 99 northstar motor with twin turbos in my sandrail. it was built by redline performance in 2004. i am replacing the head a head gasket on the right bank and while i was rotating the motor by hand i noticed that between the cam sprockets that there was differnt amounts of tension on the chain as i rotated the motor. could it be the chain has streched ? and is it something i should replace ?
thanks for any input on this !
Maybe one of the ratcheting tensioners is hung up and not taking up the slack as it should?
04-07-10, 09:55 PM
would that make a differnce when its between the 2 cam sprockets ? i would think the chain should keep the same tension between the cam sprockets and it goes from i/16'' of slack to about i/2'' slack in a couple places while rotating the motor. the tensioner keeps the rest of the chain tight ?
I'm not sure. All I know is that there are a couple of tensioners in there to keep the chains tight. I have never been in there so I'll let someone who has answer any further questions.
04-08-10, 09:06 AM
Depending on the orientation of the cams as the engine is rolled over it is likely there would be one or more "soft spots" in the cam timing: valve spring pressure is what a cam works against, so it's entirely possible that the long (tension) side of the chain run could have a tad of slack at some point. That's what the slippers (chain guides) do - damp out the slack spots. The tensioners take the slack out of the non-working side of the chains, and there is no way the crank or cams can rotate backwards enough to prevent that slack spot.
I believe it's a non-issue. You could always line up all the timing marks, pull the sprockets and chains and replace the chains, tensioners and slippers - but that's an expensive PITA.