I worry too. I've got stock heads with aftermarket cam, springs, etc but have the stock chain. Low miles on my car as well

 

Just some food for thought. I'm not saying that the ASP underdrive is the cause of the chain failure, but the last one I saw posted also had an ASP on it also. V8s have what's known as a rocking couple stress pulse on the crank so they need to be properly damped to minimize the harmonic resonant peaks which lead to damaging stress levels in the crank and attached components.

 

According to Spin, my pushrods are not offering the correct preload as they are too short. I asked him if this could have been the cause of failure and will report back. I will be putting the Katech chain and the stock crank pulley on the new setup, whatever it may be.

 

Sorry to hear that.

I also have the stock chain,ASP pulley,harden pushrods,and comp 921 dual springs kit.

 

I was on the forum all last night doing searches on this exact subject and then I read this post today, sorry brother. I do know from research the the Katech "JWIS" chain is heat treated and streched so it is much stronger and they have reported no failures.

I did speak with Jon at LG this morning and he said that he had seen some LS3 TC failures "I wish they would report them" my question is with the LS3 spring loaded chain guide/dampener. LG and LPE report they will only use the LS2 style dampener that is NOT spring loaded. They could not give me a good answer as to why but can anyone else here answer that?

Sorry about the bad news.

 

Me too. I have head work though and my cam isn't as big as yours Tony.

There honestly havn't been that many failures which is why I'd like to get to the real cause for this. With the rears we pretty much know the deal and there have been enough o quantify the cause. With the chain though there seems to be a few different trains of thoughts. One would think there would be a lot more. It'd be nice if we could solve this.

 

Did you have wheel hop at the track? Severe?

 

Seems tho that the failures are coming with the stick cars. I don`t think i have seen on auto with a chain failure on this forum.

 

Great. Another reason to hate manual transmissions.

 

 

The last go around with timing chain failures had lots of guys stating there were failures due to the Power Bond UD pulley.

It is a correlation and not a reason for the failure. Modded cars use an UD pulley and which one makes no difference. The entire rotating assembly is turning as a single unit and the UD pulley is just one of the components. The real direct resulting factor in these failures was that they were modded engines using a stock timing chain. Instead of trying to say the UD pulley was this one or that one people should be seeing that all modded engines have an UD pulley and the biggest factor in failures is the new output power. To illustrate the silliness how about this correlation.....ALL of the modded engines used the stock clutch mounting bolts so they must be the cause. Its not true, I'm just making a point.

The stock timing chain is a bad idea. Pointing toward a common mod that has been on countless cars with no chain failures is more likely the result of a rotating assembly that is out of balance from the factory. keep in mind that GM considers 70gms to be in balance so if a UD pulley is off by a few it isnt going to contribute anything to chain failures any more than a factory balance.

Get a better chain now that its been show to fail. Power output is directly proportional to failures of stock chains. Its the real correlation that makes sense.

 

My tuner used the stock timing chain too. Car had 20k miles on it. I didn't know any better at the time.

Isn't that why I am paying $100/hr labor?

Anyway, 6k miles later.........BOOM.

 

Ok I am old school, whenever you replace a cam you always replace the timing chain and gears. That used to be the rule. When and why did this change? Timing chains stretch over time and gears wear. It is always better to use new if you know you are going to abuse the heck out of it....... common sense ..... ok, old guy who has learned from much experience breaking stuff.

Consider this, the chain and gears wear in a pattern just as the old non roller lifters did back in the day. Now you reinstall the original chain and gears and change the wear pattern. (gears installed in the same, with dots next to each other but not the chain)

My guess would be that this change could accelerate stretching the chain as well as increasing the wear on the gears. It might be reasonable to compare the old parts with new ones and check for wear, but I could also be totally out of the ball park

Otherwise, I would agree we are looking at a valve train issue the hardened pushrods reduce/eliminate valve float and do not bend so something else had too. There should be one piston and valve that indicates it was the one. If all the valves are bent basically the same without evidence of any one being the direct cause then it is most likely the timing chain itself.

In any event good luck

 

Guy,
I appreciate your point, a crank damper assembly is a torsional damper for the harmonic twisting frequencies that develop in a crank shaft due to the uneven input pulses. At certain RPMs this can be worse than others due to the natural frequency of the crank. This means that the crank has some sprung twist and some of the rod journals are ahead or behind the rest of the journals, and even though this is a temporary situation when they spring back, they produce a torsional vibration. This is where a properly designed damper comes in, it damps this vibration like a shock damps the suspension springs on a car. Without a properly designed damper, oscillating mechanisms can get crazy. I have stated this earlier that a quality damper manufacturer like ATI will not make a damper less than 10% for the LS series engine because they feel they don't have enough mass available to safely damp the crank if they go smaller. It will be difficult to pin down the actual cause of the chain failure but I will use your own philosophy to make my point, all of the little things can add up, if all of the little things are addressed properly you see substantial safe gains, if all of the little things are not addressed problems surface. I am stating that damping along with balancing (two very different subjects) both become more critical as the power levels are increased in any engine but particularly true about our beloved V8s.

 

OK, you now got me freaked out!

From your post, you stated when you took the motor appart for a H/C swap your chain was already stretched. I assume all the valvetrain components were stock up to that point. If that is true, then no one is really safe from a timing chain failure....not even bone stock guys like me. It would seem swapping the cam would make the chain fail quicker; but it is going to fail either way, stock or not. Correct??

 

How can you be so certain it's not due to the underdrive pulley? You are correct, the front dampener is just one component in the rotating group, but it could move the first critical torsional resonance up into an operating range. I was on a program years ago where we had a torsional vibration issue and it was ugly. But adding a dampener moved the resonance out of the operating range and it fixed it.

 

My stock damper will be going onto the new setup. Whether it does or does not cause an issue, I am not taking the chance.

 

Stupid question....Does the LS3 have the single cam bolt set up like the '07 LS2?

 

No, but I had to swap to it because the comp cam was a single bolt.

 

Older LS ngines dont report the same frequency of issues using the exact same UD pullies. LS6/1 can use a true dual roller so no one took chances. The availability of better single roller chains is here and I dont see the correlation of UD pullies being present as any more significant than the stock chain being present for these breaks.

Since UD pullies are here forever, I think the use of the stock chain is the issue rather than the use of proven UD pullies. If there is an issue with UD pulley balance pay the 50 bucks to get it balanced.

To date very few breaks with aftermarket chains have occured and the two dual roller breaks used a power bond UD pulley, not the one used in this build.