Welcome2try's LS2 stock timing chain failed this week and did a lot of damage. Its likely that his shortblock will need a swap.

The cam swap he had done was at a tuner shop in NY and (I was not the installer as the rumor mill has it). It is common practice to use the strong LS2 chain even in higher power applications since it is far stronger than its LS1 and LS6 counterparts. The use of the chain has been done on countless installs and like the intake valve post I did, this IS NOT TO SAY THE SKY IS FALLING as some blew out of proportion what I was reporting.

I hate being misquoted so here is my exact stand on it.

I do not use the LS2 chain anymore myself. As in Craigster05's build up, long before Cameron's chain broke, I used an IWIS chain. The company makes chains for many aftermarket pieces including the C5R chain sold by Katech and the rollmaster double a single roller models.

The use of a double roller was complicated on the LS2 and LS3 because the new timing cover has the cam position sensor in it making things tight. Having used the rollmaster double roller on my LS6 in my 2001 C5, I had to move the oil pump out using the supplied spacers. The LS2 timing cover prevents this so the only other way to get the double rollers to work is to keep it closer to the oil pump. This involves some work. As with getting a big tire to fit the back of the base C6, people dont want to do extra work to go the widened wheel route so they settle for inferior wheels that stock out and tires that fit lousy. Sometimes its laziness and sometimes its fear. A double roller can fail if it is installed with incorrect gear positions. Stock is stock and you know its the right place so the stock chain or single replacements eliminate the stress of getting it right.

Due to this, most people opt to use a single roller and either use the best after-market ones like a prestretched IWIS or they just try to say they have done 32,549 cam installs and never had a break and as we all know, it doesnt meatter unless it happens on your car.

The moral of the story is that it seems that the common parts are always great because tuner X said they have countless cars running this part so it has to be good. Ask Cameron what he thinks of the LS2 chain.

On the other hand, even guys with double roller chains have had failures becuase they dont ride the chain true on the two gears.

If you search you will see what tuners use a double and what tuners use an upgraded single. Cartech advertises on thier site what they use and it snt stock. Use this event as a data point, not to panic but to watch for a pattern. Remember the LS2 (and its chain) are only 3-4 years on the market now. Also remember that people dont like to publicize failures so you wont usually hear about the botched double roller install or a failed stocker. Just because it didnt happen to many cars doesnt mean its an area to be ignored. Those not in the know sometimes say, well I have that same chain and mine didnt fail so his must have been installed wrong. There isnt much to installing a stock chain. There is no slack adjustment or alignment issue here. Its right or wrong and not degrees of wrong. saying tuner A installed my chain better doesnt make sense.

Again, I didnt do this cam install on the car in question but I'm sure it was a chain failure and not installer error. It was in for 14K miles. This topic is also on LS1tech. The general consensus when I asked about timing chains there was that an LS2 is a great chain and the best aftermarket ones had a IWIS chain. Double roller fitment isnt exact yet so you need to decide what you will use. In my case the C5R chain (made by IWIS in Germany) is a minimum for any installs I do from now on. There isnt an epidemic but I dont need it to happen on my car to know I wont run it once I see the beggining of a pattern. If its a rare occurance like valves breaking or wet shot backfires, I would have wanted someone to post on the issue to be informed for me to decide.

I hope I dont get flamed for trying to help people out here but then again with so much breakage with the Comp 918 springs that had 2 recalls people were still fighting me that it was a great spring when I was simply suggesting new installs should take advantage of the protection offered by a good dual spring. Like its been said countless times before, Accountants make poor mechanics becuase your minimizing parts total cost doesnt make for a safe running car. If you cant afford to replace your engine you shouldnt mod your car, so it stands to reason if youre sitting there with a calculator trying to squeeze out a cam install with the cheapest parts you can get, you cant afford to mod your car.

Chuck At Corvettes of Westchester (also not the cam installer) stepped up to the plate and stayed late nto the night to try to help Cameron and even drove him home in the middle of the night. I will do what I can to help him but I have the move to Colorado to do. I am sure he will be up running but I will bet all my cars what part he wont use in this new engine.

 

Wait, there aren't people/shops out there that actually use a stock/OEM timing chain set when doing a cam swap are there?
To me that's almost like using the stock valve springs with a big cam.

I would never, repeat NEVER, do a cam swap on an LSx motor without also upgrading to at least a stronger/aftermarket single timing chain...most likely I would even take whatever steps necessary to get a double on there.

 

Was it a stroker motor?
Did it have an underdrive pulley?
If so which one?

 

Thanks for the info Spin.

San

 

Its a cam only Ls2 with an UD pulley...powerbond.

What difference would the UD pulley make?

 

Little birdy told me that they have seen some underdrives (specifically powerbond) so far out of balance that they suspect the balancer is creating some harmonics issues contributing to some timing chain failures. The common theme from the ones I've heard of, all had powerbond underdrives that were seriously out of balance. However, all but one (now two) of these motors that I know of that have experienced this type of failure were strokers, that I understand, have their own harmonics issues. Have the underdrive checked for balance if it is not already back together. I would guess the results of that test will tell you alot.

 

I dont see how a pulley being out of balance does anything to the timing chain. The clutches are far worse. My stock LS7 clutch required 13 holes to be drilled in one side of the pressure plate to get it balanced. GM also considers 70grams to be in balance for a stock crank. Either way there is no force working on the chain differently. It pulls in the direction opposite the motor's rotation and at high rpm's it has more centrif force tangent to that plane outward. High rpms and coming on and off the gas makes this an occilating issue. Perhaps you suggest the out of balance creates a higher harmonic of such occilations? This is a great excuse to use a ATI superdamper.

I think youre chasing a correlation but I like the contribution to the topic. To test your balance theory I will take a pully over to my uncles hangar and give it a spin to check the balance. I have one sitting here.

 

It is not my theory.I am not chasing any correlation and I have absolutely no dogs in this race. I am just sharing what I was told by a very well respected tuner and by owners of cars that experienced this very issue. They can remain nameless unless they choose to chime in here. Just looking to contribute to information to better the modding experience for all of us. I know you are too. To test the theory correctly you would need the actual balancer off the car that had the failure.I would be interested in the results of that test.
Oddly enough, my LS7 clutch was only 8 grams out.

 

The statement had nothing to do with L7 clutches other than to illustrate that you cant account for all the things that would throw a rotating assembly out of balance. The crank, flywheel, pressure plate, and pulley all spin as a unit and I was showing that the balancer cant possibly be more of an issue than all the others combined. If we were talking about crank bearings then you would have a point. Before I say anything about a powerbond pulley I would want to see what proof the tuner has as to the balance of the pulley. Did they check the balance? If so that is a valid data point.

I will give Cameron the new pully and test his old one.

As far as the correlation statement, since just about every car out there uses SLP or powerbond for pullies, it stands to reason nearly all cammed cars with chain failures are 50% likely to have a powerbond pulley. I dont think it has anything to do with the issue balanced or out of balance. I just want to supply a data point so it doesnt hurt the PB pully's manufacturer from taking a hit when it may not be their fault. I know of only one other guy that had an LS2 failure and he has the powerbond too. Its a 2005 and it wasnt a stroker. He did the cam install himself and it was 3 years in use when the chain failed. Somewhere along the line you say a stronger chain takes more abuse. Would a IWIS single have been any better? If yes then the argment about the cause isnt as important as the fact is that you should use the best parts available and dont try to save money there.

I wont lie to you that I think of checking the pulleys everytime I do an install. I think the H/C install needs to have that checked too when my name is signed to it. In the end, you have affected my policy all the same just by raising the question. I do however think, pulley issue or not, that a stronger chain stands a better chance of surviving any issue.

 

All valid points and I agree with you. I'm definitely not trying to throw any vendor under the bus. LPE uses ASP pulleys. What is Cartek, Katech, LG recommending with their packages? Hopefully some more owners that have had this issue can chime in with the failure analysis on their cars and we can build a knowledge base here and get to the root cause. Curious if LG has seen this issue, he seems to have strong opinions, maybe he will offer his here.

 

As a side note the LS7 cannot fit a double roller. When building my setup we looked and there is not enough clearance with the dry sump setup. We were thinking of actually changing the the pan so that I could install a double roller, but in the end we decided to go what was recommended to us from Katech - LS2. We did copy the LS7 setup and added a "tensioner" that stops the flexing of the chain.

IMHO the breaking has to do with flexing and snapping back into place that I believe happens under loads and this is why most of the broken timing chains I see happen on RR cars. For the most your normal driver will not have problems. Your driver that is hard on their car would have to worry more. I know Cameron was not easy on his (btw sorry this sucks I know it happen to me at WGI).

I know of plenty of double roller and LS2 cars out there with no issues. I though broke my double roller after 3 years of RR. I personally know of 1 other double roller that broke after a much shorter time and 2 other LS2 that broke - all were RR cars.

I think upgrading your timing chain when you are having work done on your car does make sense, but I also dont want people that are driving stock cars to think that they are going to break their timing chain because frankly I have not heard of this happening.

 

Even more than that, the ride to drive Cameron home was 50 miles EACH way and after midnight! That's the favor of a good friend, not a business associate. Chuck's giving nature is unbelievable at times...way to go Chuck


In all fairness, for those who do not know him or have seen him drive, Cameron does beat the pants off his car every time he gets behind the wheel....he admits it himself, he lives at 6000 rpm and enjoys every ounce of performance the car can give him, and will race anyone without regards to the odds. His Mustang saw hundreds of track races, and he knows how to get the most out of a car. I admire his driving skills so much, I asked him to be the one to try and see what my new motor can do in the 1/4 mile as toe to toe, he can outdrive me 9 times out of 10.

I still have my old chain, which had less than 10K miles, and the stretch difference compared to a new chain was substantial. I will get a compare to a new chain and post it for all to see as soon as I can get another new one, just for everyone's information. I'm confident it was 14K miles of high reving torque snaps, 5K launches etc combined with stronger new valve springs, higher lifts and a slightly stretched and weaker re-used timing chain (which may have even had an inherent manufacturing weakness) is what caused the failure, not vibration harmonics from an UD pulley.

i sincerely do not believe that this was a case of a Powerbond issue, as we don't know if he had one yet, or more importantly, even if one truly exists at all. I'm sure c6400hp is trying to be helpful with information that he has heard, I don't think he intentionally means any harm to be directed at Powerbond. We can all share info to pool, and sometimes you can spot a trend this way. But until you see confirmed tests, from reliable, confirmed sources, then you can know for certain that there is a documented issue and good cause to avoid a product.

So please anyone reading this, do not think there is a known problem with Powerbond....I already saw in another post a member warning another about Powerbond pulleys. No one is crying wolf....it is an informational post about modding and being sure you use correctly matched parts and not to save a few bucks when much is at stake, please do not take this post out of context. It is an FYI for those considering mods themselves, or when a shop is doing the work for you, don't look to save $150 on a cam swap.

Remember the o-ring on the space shuttle Challenger??

If you have any doubts with a rotating assembly, have it checked before you install it for peace of mind, no matter who made it. Just as you wouldn't install a tire with checking it's balance, (or a flywheel, or a clutch, etc) you can have your shop check the balance of your UD pulley to be sure. I did, my Powerbond came back fine. If yours didn't let us all know...the more information we can share, the better we can make our mod choices, the SAFER we can all be behind the wheel.

 

Wow, that stinks. I got my timing chain from Texas Speed and there was still a bit of slop in it. I can't remember which one they use. On the bright side I bet Welcome builds a new monster.

 

Spin,

THANKS FOR THE WARNING!

Cameron,

i am very sorry to hear that, and i hope that all goes well with the rebuild.

Tony B.

 

Cameron, you have my sympathy. I hope the shortblock & Heads are not shot. I remember blowing a timing chain in the 70's w my 65 vette.
I was lucky and just bent tsome valves on the 350 cu in engine. At that time I just simply got some new valves & lapped them in. Today things are different. I hope you are back in business soon as you have some great support there with Chuck, Guy & Craig.

 

I would definitely agree with what has been posted here. Especially since its $130 of preventative insurance that could potentially save you thousands. Unfortunately, I had not read up on timing chains at the time of my cam swap, so I have the stock LS3 chain in there . Again, if I have a failure, you can bet it will be posted in here. I have still yet to realize why people don't speak about their parts failures. It only hurts the corvette community as a whole

 

if you cant afford to replace your engine you shouldnt mod your car,

There is the operative statement in all this information! It's exactly what's stopped me from modding my engine at this point in time! Thin pockets make for trouble when engine modding for power! That usually will come back to haunt the OP in the end. I'm not doing any engine mods until my warranty is done and I have enough money to replace the engine in case of a disaster. It happens to the best of the best so it can sure happen on thin budget a lot faster.

I sympathize when someone pukes a motor but they also knew (or should have) exactly what they were getting into from the start. There are no free lunches in life or in high performance engines! More power usually carries more risk of engine failure.

It's really great reading the technical info dolled out here from the experts. When I'm ready to do my engine it will get done by the best I can find around here! I promised myself that 300 or 3000 dollars won't be an issue because I want everything done as good as possible. There will of course be a budget but not before all the right things have been figured into it.......

 

Sh*t!!! Damn Cameron Sorry I missed your call last night. I'm away for the week. After reading this I wish I was able to pick up. I hope you build her back up strong and get on the road again soon.


Guy, Craig, Chuck, for helping him out. Since Cameron is still on suspension do you know the driving conditions during which the chain broke? Have you seen a pattern to when this occurs and are there any warnings?

 

I dont recall but I think he was starting the car. I'll ask him later.

If I'm right you can prevent this from happening to your car by never starting it.

I have free heads for him so its up to if the shortblock survived. Anyway, whatever it takes....no friend of mine is eating the full cost of this.

 

If one of the cyllinder walls is scored ithink it can be sleeved. I know it was done in earlier times. Just a thaught. Its great you guys are right there selflessly offering your services & Parts. You are truely a great
bunch of guys.