laurent_zo6

You seem to be out of the danger zone but it's a crap shoot at this point. It seems there was a bad batch of springs so who knows where they landed. You could go 200k without a problem or it could happen next week.
Since I was in the danger zone (April 2002 built) I replaced mine for peace of mind.

GenerationX1

Yes I do plan on changing mine... especially with bolt ons and a 100 shot of nitrous.

racebum

might not be

the earliest 02 springs i remember seeing were bare metal with orange dots

the yellow ones that came later were the suspect springs

Trash

I absolutely concur. It might never happen with the yellow springs or break at the next start up. It's doesn't have to be a motor that's running at upper RPMs either. It's happened at cruise, idle, accelerating etc. Virtually all regimes.

On a separate note, the 2% failure rate that has been mentioned, if accurate, is an abysmal production failure rate.

racebum

no one is honestly sure if it's that high, we only see a sliver of total z06 production here on the forum.

BUT

it's high enough most of us don't want to risk it

LS7 is the same way, not every engine had out of spec guides, but, enough did that it was a problem

GM never recalled either, just a money, math, warranty game

4drturbo

Springs - 12499224
Intake valve seals - 12482063
Exhaust valve seals - 12482062
Valve cover gaskets - 12637683

So this is what I need to order?

My car has a ProCharger on it, only running 5 lbs. 02 z06. 55k miles

Good idea to put some COMP pushrods in there too while they are in there? I also heard someone say to put some dual valve springs instead of the ls2/ls3 ones? New keepers too? Anything else besides spark plugs and wires while I am in there? I don't plan on going over 500whp. I want to keep it reliable as possible.

I have only had my Z06 for about 2 weeks now and I am afraid to get on it at all. I do have the yellow springs and sit in the high risk group. :/

thanks guys for any help.

racebum

factory cam and factory redline yes

if you change the cam then no, this won't work

hardened or stronger pushrods are needed with stiffer springs, if you use oem springs use oem pushrods, your existing ones are fine

Kevin 64

Those who say it doesn't/wouldn't/couldn't happen--It did to me. #1 cylinder, dropped the valve, hole in piston. Happened while pulling out from a stop light at low speed. About 79k miles on the engine.

racebum

was your block okay? if so at least it didn't wreck the engine and you could just pop in another stock piston

Kevin 64

It just so happened to occur about a month before I was headed to Afghanistan. As luck would have it, a guy in my club got me a new crate LS6 (2004 version) for cost while I was away so i dropped that in. I have the original and will someday tear it down. I can hook a fingernail on the cylinder wall, so my hope is I can maybe hone it since my understanding is you can't bore out more than .001.

BTW- there was metal from the piston in the intake, so who knows where all the metal got too......

racebum

i'd have to look at my notes but i'm fairly sure you can bore the block .010 over for oversize pistons if need be

if you can hook a nail you might be able to get by with a rehone which would allow a stock piston. a ball hone on a drill can be done if you're careful and stuff the bottom full of rags so crap doesn't get in the bearings and crank. if you re hone that cylinder you need a new ringset. i would try the ball hone method on a drill before you pull it all apart, may be able to fix it without total disassembly

if that scratch doesn't go perfectly smooth to the eye and finger, you're going to have to either to an aggressive hone at the shop which increases PWC and shortens ring life, also can rattle a bit since the piston will be a bit loose

or run one oversize piston and bore that hole .010 over

at that point you may just buy a set of .010 pistons and rebore the block for new pistons and rings

ssrallyred

My 03 was built after the most common vin's with issues but I just this past Saturday put in the PAC's and it was right at 3 hours from start to finish and did all the seals and VC gaskets. Used the Crane dual valve spring tool. I also found a great deal on the SLP 1.85 rockers so installed those also.