JZ28

iTrader: (3)

OK, here is the story. Replaced my cam a while back and put in a new OEM timing chain. Also installed Comp 918 springs. After a couple thousand miles when I would give it anything over about half throttle under 1500 rpms or so I could hear rattling from the timing chain. Anywhere over 1500 rpms and it wouldn't do it. A little later on I replaced the heads and they came with dual valve springs. Still on the same chain, still the same noise. Then I replaced the timing set with the Comp Cams adjustable roller single chain. The noise was gone...for a while. After a couple thousand miles the same thing started happening again. What would cause my car to stretch chains like this and what can I do to fix it? It's in my sig, but its a 2000 Z28 LS1. I don't mind doing the chain again, but I don't want the same thing to keep happening.

Tally TransAm

iTrader: (17)

theres no way you are stretching these timing chains. something else is going on

DONAIMIAN

iTrader: (18)

FYI-The factory chain is designed with slack in it.

vettenuts

iTrader: (4)

There is a harmonic in the timing setup, but its at a higher RPM. A timing chain damper might help if it is truly the timing set that you hear and not something else like the oil pump.

Grimes

iTrader: (3)

Agreed...I never hear of stretching chains...not to mention two of them. And on a slightly off topic, amazing seeing Tally TransAm here again. Where you been?

Tally TransAm

iTrader: (17)

haha, im always on here, just rarely post. recently though ive been going on posting binges

to the original poster, do you have a complete mod list. i had a similar noise in my car a couple years back, sounded like a light rattling under accel around 1500-2000 rpms under load in higher gears. turned out it was detonation from a vacuum leak from where the pcv hose going into the intake had melted. not sure if thats your problem but im betting its not timing chain related

JZ28

iTrader: (3)

It seems very odd to me as well, but like I said, when I replaced the timing chain, and that is all I did at that time, the noise went away for a couple thousand miles. I have a lot of trouble believing that I stretched an aftermarket chain as well, but I don't know what else to think? It only happens at low rpms in higher gears, and occasionally off the line. I have had the car on the dyno 2 times with no detonation.

As far as mods, here is what I have in the motor. SLP CAI, LS6 intake manifold, ASP pullies, Katech manual belt tensioner, Comp Cams adjustable roller timing set (single chain), TR 224 cam, TSP 5.3 heads (11.25:1 compression), patriot dual valve springs with titanium locks and retainers, LS7 lifters, TR hardened pushrods (stock length), ARH long tubes and Y with cats, SLP LMII cat-back, EGR and AIR delete, TR ported oil pump, NGK TR55's, MSD wires, uhhh......I think that is it for the motor. Have had it on the dyno twice. 415rwhp/402rwt SAE corrected.

Any ideas would be appreciated. Thanks guys.

JZ28

iTrader: (3)

bump:

purdueranger

iTrader: (11)

did you ever measure the new chain to the old one with no slack in either chain to see if you are really stetching it. i can see if you had 100k on a chain then put a new one in, then you will see some stretch in it. I saw this when I put a double roller chain in my jeep, stocker had 108k on it.

Are you using any loctite on the bolts to keep them from backing out. I can see it backing out and causing you to hear some noise.

JZ28

iTrader: (3)

When I tore it down to replace the OEM chain with the Comp timing set, there was clearly quite a bit of slack in the chain. The new one was pretty tight when I installed it. I didn't actually measure them, but I could tell that there was a big difference. No problems with the bolts backing out. Used loc-tite and torqued them to spec.