02impactblue

Timing chain let go at 5k on front straight at NJMP. Looks like a new motor is in my future. Any recommendations for a reliable option? another LS6 or maybe LS2 or all out custom build. I'm not looking for more power just a solid motor. I ran an ls2 for 4 years with no issues and switched back to a c5 and the motor let go after 15 track days. I now understand the timing chain is a weak part on these engines. Wish I had researched prior. Any recommendations?

Eric D

The chain isn't the weak link, it is the fuse. What harmonic damper are you running? What other mod's did the engine have?

96CollectorSport

I think Scoggin Dickey has a few LS6 long blocks still availible for around $3700 shipped, hard to beat that. It comes with the Caddy oil pan (so hopefully you didn't hurt yours) and you will need to swap out the pilot bearing, other than that just transfer over the rest of your parts and you should be up and running in no time.

waddisme

I did a forged LS2 when mine LS6 let go. I got a fully forged LS2 al block from TSP, MS3 cam, Patriot heads for under $7k. It was also another $1500 labor and parts to get motors switched. But for me, I sold supercharger kit, block, heads from old motor for over $5k, so I ended up less than $4k for fully forged motor that will hopefully last a long time. BTW, I did the upgraded timing chain from IWIS and no underdrive pulley. Seems like LS2s were having timing chain issues and the common denominator seemed to be underdrive pulleys. I didn't think it was worth the risk for the few extra horses. Good luck on your new motor.

02impactblue

Do you have a link or part# for the long block option. I was all over their site and I only see the LS6 crate option for just under $6K.

02impactblue

100% stock including air filter!

sothpaw2

Sorry to hear it. Nothing to add--conventional wisdom here has been the LS6 w/ the caddy oil pan for $3700.

C5ZEE06

funny (not really)..lost the C5R timing chain on my LS2 stroker motor at the track last weekend too...and i do have a UD pulley.
maybe i need to go back to a conventional pulley for the rebuild ?

billy25us

I broke two timing chains (both of them were c5r chains) in back to back weekends on a ls1 with a underdrive pully. The pully did seem to be the cause. I bought a crate ls6 from engine depot for 3250. Sold my old motor after I put all the stock stuff back on for 1500 so I came out pretty good.
http://forums.corvetteforum.com/c5-t...ideas-why.html

Eric D

Are there any changes to the rev limit? If not, the reason for the break may remain a mystery.

As far as the harmonic damper, being underdrive is not the issue, it is the frequeny the damper is tuned too.

C5ZEE06

Eric how does / why would changes to the rev limiter obscure the cause ?

from reading up here, I think Ill go back together with a 10% Powerbond.

gtpvette

Looks like $3245 shipped. Not bad at all.

http://www.ls1tech.com/forums/sponso...0-shipped.html

If you're going to part that broken motor,, I need some covers.

Eric D

With a stock motor there are cam drive modes at higher rpm's where torsional phase between the cam and crankshaft go out of phase to each other putting higher than normal loads into the chain.

I would also go with your thoughts of using the 10% Powerbond.

rustyguns

anyone have better luck when they install a timing chain guide?

wish someone would start selling those again!

seems it would lower the chain slap

C5ZEE06

shop just confirmed that my UD pulley was an ASP (it was installed by prior owner). No chain damper or tensioner was in place. I selected an ATI 10% pulley for the rebuild. Looking for a LS2 damper to install - if there is such a thing.

96CollectorSport

IMO the only balancers to use are ATI (with the softer rubber) or stock GM.
The way to tell if your chain has failed due to harmonics would be to see if there are any "stiff links". If you run the chain over your finger and see or feel any links that move stiffer than the others it is from the racheting effect that happens when you are at peak torque.
If you look at the chain and it's just broke (no stiff links) it was probably just a weak link
Check out the number of failures over on LS1tech with the ASP pulley, I found a few a while back when I was looking into chain failures.

2000BSME

a fuse protects, a broken timing chain destroys the engine. Terrible analogy that you've made.

Eric D

I respect your opinion and from your prospective you could be right. I think it is important to understand the forces necessary to break a timing chain are higher than what most people might think. It is close to the force of bouncing the weight of the entire car back and forth on that little timing chain. My take is this; a fuse is in place to limit damage. It is used to avoid catastrophic failure. Having to replace parts that can be unbolted and replaced without major teardown I believe is less than catastrophic. If the cam drive chain where to stay intact and the engine allowed to go higher in rpm during one of these out of phase occurrences there is a very high likelihood the next item to break would be the crankshaft. I believe a crankshaft breakage would be catastrophic as it would most likely take out the block as well. Hey, like you it is just my opinion and I believe the timing chain fits the description of a fuse.

Katech_Zach

I've heard of 3 other timing chain failures with ASP underdrive pullies. The solution is a ATI damper and C5-R chain.

Does the OP have an ASP UD pulley also?

Eric D

02impactblue, the OP, stated in an earlier post he was 100% stock when I asked what harmonic damper he was running.

What are the differences in the C5-R chain to the current LS2 chain? Does the C5-R chain use the same sprockets?