ls1 1990 VN

My timing Chain broke while circuit racing, 4 of my Mahle pistons took a hit but should be ok, Got 6 bent valves was lucky with the chain as when it broke it spun a bit then just lay on the bottom of the case.

My Question is: What is the difference between the valves that TSP use in their stg 2, 5.3ltr heads & standed LS1 valves.

Cheers guys from NZ

team39763

iTrader: (3)

My buddy told me that his TSP valves weighed in slightly lighter than his stock LS1 valves. He didn't mention any other differences though.

Any ideas what caused the break? I've read that these underdrive pullies are causing the timing chains to break.

KRAZY K 2000 TA

iTrader: (5)

Glad to here your Mahle pistons are okay they are what i am installing in my 402 was worried about there durability.

vettenuts

iTrader: (4)

Which UD are your running? If road racing, a timing chain damper is a must.

02*C5

iTrader: (1)

Yes you need a damper it will put pressure on your chain to keep the chain taught at all times. There is a lot of shifting of rpms in road racing putting a lot of stress on the timing chain.

ls1 1990 VN

It's a Powerbond 25% underdrive. It was while circuit racing, a circlip type piece of metal came out on my sump magnet in my last oil change, it had broken in half. No one could tell me what it was from, i did a search on here after my mishap and came accross someone who had posted the same clip & chain.
I will look into getting the damper with my unfortunate shopping list.

If my pistons weren't forged & have valve reliefs those 4 would've been history.

ls1 1990 VN

Can't understand why they would be lighter as they are a budget performance head,

Lighter would be sodium filled valves which these won't be.

The Alchemist

iTrader: (19)

Definitely reccomend a true harmonic damper for future use. Not having a harmonic damper is what can cause bad vibrations from the crank, up through the timing chain.

ls1 1990 VN

Thats something i will look at now, have you any idea about the difference between standed LS1 valves & those used by TSP in their 5.3 stg2 heads?

SSDION

Broke a dual rollmaster a few years ago, got 13 valves bent and oil pump desintegrated!! The problem I think is the chain too tight during install. With aluminum block, thermal expansion increase center distance and put more and more tension on the chain. That's what I think happened. Just a supposition. Install LS2 chain after rollmaster broke, never had the problem again with the same balancer on my last 383 setup.

ls1 1990 VN

How long have you had the LS2 chain on your 383 for now?

vettenuts

iTrader: (4)

The harmonic damper is a major contributor to broken timing chains. My recommendation would be either an ATI damper or stock. There are some very informative posts by "427" on this subject, I have included links below. They no longer make the LS1/LS6 timing chain damper so you may need to make something that will work. There is a known RPM range where harmonics wreak havoc with the timing chain and road racing puts the motor within that range more then any other type of event (drag racing, etc.) so special attention will be needed to avoid this happening again.

Here is a link, pay particular attention to posts made by "427". He has a lot of information and has done a lot of work with broken timing chains. Link_1

Here is his other post that has more good information: Link_2

ls1 1990 VN

Thanks vettenut for those links, it's valuable imformation that i need to act on.

Cheers

Cheatin' Chad

iTrader: (3)

For anyone that doesn't know 427 is Kurt Urban. formerly of Wheel 2 Wheel and now owner of Kurt Urban Performance. One of the guys involved in putting the first LSx engine into the 6's and one of the most knowledgable LSx guys in the world.

I have no idea what broke your chain.I don't know if it's the cause or sympton of other problems.I do know those chains aren't exactly easy to break. I suspect there is something else amiss here.

It definitely won't hurt to listen to these guys and do as much research as you can.

ls1 1990 VN

This i definately am, i don't want this to happen again, i dodged a bullet here with minimal damage.
I need to find out the part number of the ATI Damper he has suggested in a previous link above

Cheatin' Chad

iTrader: (3)

ATI part number: 917277

10% UD w/40durometer rubber

http://www.atiracing.com/products/da...ts/damserp.htm

ls1 1990 VN

I already have a Powerbond 25%, this is about why a timing chain broke & what is needed to not have it happen again,
You might like to read the threads by '427' that vettenuts has put 2 links to, very imformative.

I have been intouch with '427' ie Kurt he has told me that that particular pulley would not suit my power band, but to use this.

Kurt Quote,

The "44" ring damper is tuned for a lower power band, you should use the standard 3 ring underdrive from ATI and the chain damper. This will make your timing chain happy!

vettenuts

iTrader: (4)

Thanks, I didn't know that but have read his posts in the past and could tell he was very knowledgable.

1SLwLS1

iTrader: (6)

What about an ATI + Katech C5R chain, that ought to eliminate the problem, haha.

Silver408z

iTrader: (1)

If you want my opion take the motor out now and have it gone through. A valve hitting a piston can cause enough damage to bend a rod or mess up the rod bearing. I had a intake valve seat fall out and then it caused the valve to hit the piston. Every thing looked ok and I tried to just replace the place the piston and the heads. After it was back together and I saw there was oil preasure issues. It all had to come back out. Take it out now and have the rods and bearings checked now imo.