stevensa

Hey Guys,

After reading a recent thread on here asking about which damper to use to prevent timing chain failure I did some searching as I have never heard of this before.

Last summer my car started demonstrating really poor oil pressure after a session on track, and it seemed like the oil pump had failed. What really happened was there was a double roller timing chain on the car (don't know how old or what brand, previous owner installed) and one of the links had cracked and stuck out enough to "machine" a hole into the pickup side of the oil pump which made it very hard for the pump to pull oil from the pan.

I just wrote it off as some random mystery chain, that may not have been installed properly being the issue and replaced the chain with a new LS2 part.

I have been tracking the car happily since then and not thinking about it.

Now I am reading about how the ASP crank pulley (which I have) could be the cause of this issue and I would like to get some more info to help determine if I should swap to an ATI unit.

1. What data is out there showing the issue with various pulleys, and how the ATI avoids these issues.

2. How can I tell what caused the first chain to fail?

3. Are there any signs that the pulley is causing damage?

4. I keep reading about the "bad" rpm range for harmonics, however I have seen that range from 4800-7000? What is the real "poor harmonic range" and where is this data coming from?


Thanks in advance,
Andy

geerookie

Read from about post #105 on in this thread.

http://forums.corvetteforum.com/auto...-sunday-2.html

Different motor configurations have different harmonics. One damper does not work for every application. The same damper will work for all stock motors that are the same.
The stock GM damper on an '02 405hp LS6 is different than the one on the '02 LS1 even though they are the exact same block.

96CollectorSport

Jason from Katech has seen a unusually high failure rate of timing chains on engines with ASP balancers on them. We had one engine that broke 2 chains with an ASP balancer on it, now it has an ATI and we haven't had an issue in over 2 years. (We sent the engine to Katech to try to figure out why and after the rebuild the balancer was the only change in the new motor - another "big name" engine builder installed the ASP balancer on a previous build, we haven't used them since.)

If you think that the dampener isn't doing it's job take a look at the old timing chain, if it has stiff links - links that don't move freely - then your balancer isn't doing it's job.

If not dampened properly the harmonics will push and pull on the chain violently trying to break it, and eventually the harmonics will win. Katech said a lot of this was around peak torque, which is right in the wheelhouse of a track run motor.

If it was me I would just replace the balancer - and while your there you may as well replace the timing set so eveything has a fresh start.

Shaka

Right. Service your damper regularly. Keep it cool. It absorbs a lot of energy which makes it hot. Change timing chain and valve springs every season along with a damper service. Sprockets also. Weak valve springs cause combustion pressure variation which your damper is not designed for. Check these vids. Keep your engine alive. Don't buy cheap stuff.

http://www.youtube.com/watch?v=i_NpzU4pGjc

http://www.youtube.com/watch?feature...&v=_REQ1PUM0rY Check what happens in float. Remember, you have big heavy valves.

stevensa

Thanks for the info, does anyone have any actual data comparing the different dampers just out of curiousity?

I will inspect my old chain when I am home in a couple weeks to look for tight links.

It sounds like the more comfortable thing to do is replace the unit with an ATI. Depending on how my old chain feels, I will probably just go ahead an get the ATI unit with a new chain at the same time and also inspect the valvetrain. I wish I knew about all of this while it was apart replacing the original chain, or that the previous owner installed an ATI from the start.

Pumba

Andrew,

The week before the Daytona 500 I had the opportunity to spend the day at Earnhardt-Childress Racing Engines' NASCAR engine build facility. I was allowed ask all the questions I wanted and take notes, no pictures were allowed, and go anywhere I wanted in their shop.

ECR Engines builds the Daytona Prototype 5.0L engine. This engine is restricted to 7,100 rpms by the sanctioning body, and it makes 600 crankshaft horsepower. The engine uses the LS9 block and is destroked to take the displacement down to 305 cubic inches.

The Daytona Prototype, NASCAR Sprint Cup, NASCAR Nationwide Series, and the Camping World Truck Series engines are ALL equipped with ATI crankshaft dampers. Oh yes, the day before I visited ECR engines, I had an open door visit to the Roush-Yates Engines' NASCAR build facility. ALL of their engines use ATI dampers.

That's a long way of saying change over to an ATI damper. I prefer the 10% underdrive version - part number 917278.

In terms of a timing chain, dump your existing dual row timing chain and get a Katech C5R single row timing chain that uses the stock single row gears - http://store.katechengines.com/c5-r-...chain-p30.aspx .

Also, while your have the front end of the engine open, change your oil pump to a Melling 10355 pump:




Good luck with your motor.

-

stevensa

Thanks for the info, I already have the better pump and the double roller chain has been removed, I just wish I knew about the damper issue while it was apart the first time! I plan to change out the damper to the ati in the future. Thanks for the post.