Cobra4B

Wondering when/if I should service the timing chain and vavle springs on my stock motored '01 (bolt-ons only).

If I'm going to the trouble to do this I mgiht as well put a cam package in the car and an LS2 chain.

What's the concensus?

Oh and I'm pulling my headers to get the air tube hole fixed etc, so it's the perfect time to get a radiator/oil cooler.

Ahhh... it adds up! radiator/cooler and a cam package

RAFTRACER

Timing chain and new valve springs , very good idea. I've already done this on my own '03 car with only 2600 miles. Ive seen some T1 cars eat timing chains and have catastrophic engine damage..................

95jersey

Nice time for a cam, if you pull the chain....hmmm.

BBQ

huh? timing chain job after 2300 miles?

Timz06

I don't know about the LS1 timing chain, but getting to it on my LT1 is a pretty big job, gotta remove all the stuff in front, balancer front cover etc. On the LT1 you will mess up the seal with the oil pan, so you have to drop the pan to get the new gasket in, major pain.

Valve springs would be easy though. you could change them, but I doubt they are worn with just the few events you have done.

Tim

RAFTRACER

2600 miles, average throttle angle of those miles 90%, average engine speed 5000 rpm, 7300 rpm rev-limit, max accel and decel all the time

=

new valve springs, timng chain and new piece of mind..................

VetteDrmr

What about a bone-stock motor (including PCM)? I've asked this question over and over, but no one has been able to give me any decent data on when to do this work.

It's kinda the old quandry "don't fix what isn't broke" and "why did you wait that long?"

TIA, and have a good one,
Mike

Cobra4B

^ Exactly... I'll proabbaly just wait until it's time for cam and do it all together.

Lancer033

It's simple, look far enough into your crystal ball to see if break, then change it the weekend before

VetteDrmr

The week before:
The week after:

gpm30236

Have some recent experience from the teardown of the engine in silver . 83,000 miles. appoximately 50 track days some with 2 drivers / session . always good oil/gas ,

Timing chain somewhat loose.

Valve springs replaced at about 70k 1 broke on easy commute
Replacement valvesprings after overrev Ok

Probably good insurance to replace valve springs yearly if you are doing lots of track days.

John Shiels

My car sees work like that it's on or off. Replaced springs at about 2000 or less then the second set went less than 900 miles. Switched to Comp 921. I rev to 6700 max I have all the cooler so temps are not a factor. Whne they just broke I was lucky it was only one slightly bent valve. Near 1900 bucks. Could have lost the whole motor so I feel lucky. Do it.

0ATI Performance

Valvetrain failures can be catastrophic, especially on the wallet. Not much remained of this Corvette engine, as valve pieces found their way around the engine via intake manifold, rods got bent, dents in pistons, etc. Pretty much ended up an expensive pile of scrap metal. The valve piece in this picture was hammered into the port by the piston.

Attachment 47594827

And as Murphy would have it, such failures always occur at the worst possible moment. This one happened in 2004 while loading the car in the trailer for the SCCA Solo National Championships, then night before we were supposed to leave.

New valve springs are cheap insurance.

Bob

VetteDrmr

Bob,

Question: Was that failure due to a spring failure? And, if I'm going to change out my springs (stock engine, 140K+ miles, autocrossed several times a year), do I need to replace anything else (spring retainers are what come to mind).

TIA, and have a good one,
Mike

0ATI Performance

On this particular engine, the valve stem broke first. Similar disaster would happen if a spring broke and the piston hit the valve.

If you only autocross several times a year, it may not be a big deal. If your engine spends most of its life above 5000 RPM, and especially if you have a stock engine and tune up the rev limiter to 7000+ RPM, then I'd be changing the springs at least once a year. When changing springs I'd also change the retainers etc. Springs can be changed without removing the heads.

Think of it as buying "engine insurance". Other failures like spun bearings can usually be fixed with a basic rebuild. If you drop a valve, you may find yourself with an expensive boat anchor.

Bob

VetteDrmr

So, for a stock engine, would you just go with OE springs and retainers? I know that xxx springs from yyy supplier are *the* things to have for a modded engine, but I don't have any intentions of going inside this engine. If I ever have the PCM tuned, one thing I'm planning on keeping is the stock rev limit.

Thanks for the info, and have a good one,
Mike

Maineiac

0ATI Performance

If you don't raise the rev limiter beyond stock, and especially if you don't race much, then stock parts should be fine and save money. Also if you race in a stock class, you can't use different parts.

The primary reason for higher valve spring rates is either higher rpm's or bigger cams. You need enough spring force to close the valves (keeping the lifters against the cam) or else you get "valve float". If it is bad enough the piston could come up and hit the valve before it closes - BAD. Generally though, there is a severe drop in power before this happens so you tend to back off.

Springs over time can degrade and lose their spring rate, decreasing the RPM at which valve float occurs. They can also fatigue and break.

Again on a street car probably no big deal, but if you are going to race and run up against the rev limiter constantly, cheap insurance.

Bob

Dr Chill

Well, last month I lost a timing chain going 120 mph at Sebring. Car had 10,000 miles and medium cam and JWIS timing chain. This is what happened. No better time than the present to upgrade the timing chain or valve springs.

Dirty Howie

Just asked this question to Tony Mamo (AFR) at the A&A BBQ last weekend.

Answer: every 20K miles for street/track car.

I probably have 30K miles and 14 track days since I did my heads/cam.

I should get this done before ......... :o


DH