Is the 2.8l really what I want?

[caffeine]

I've always had success with the stock chain and 986 springs. I believe the 986s are easier on the chain than the 915s. IIRC the 915s will support higher revs but not as much lift as the 986s. That being said you probably won't be spinning much past 7k anyway and the 986s are fine for that.

[Ghosteh]

I doubt I'll ever get it near 7K, but who knows. It's not going to be a dragster; the car has skinny 15" tires on wire wheels! lol!

Just ordered the 26986 springs, valve seals, and a WOT street/strip cam.

Ok, here are the timing chains on my two motors. Looks like the sprocket on the end of the cam connects differently to each one (1 bolt vs. 3 bolts). And I haven't checked the diameter of the cam/crank shaft to see if they are the same, but I'm betting they are.



How am I going to make this work? My machinist friend could probably alter the 2.8L sprocket to mount on the LX9 cam, but if there's a bolt-on solution using a different year/model part, I'd rather go that route.

[Guest]

Why are you looking to use the older timing chain?

The LX9 timing chain will work with your new cam, and be bolt on.


Sent from my iPhone using Tapatalk

[Ghosteh]

Why are you looking to use the older timing chain?

The LX9 timing chain will work with your new cam, and be bolt on.


Sent from my iPhone using Tapatalk

The 2.8L timing chain is much heavier & brand new. I thought the '99 and earlier chains were better to have, and since I have a brand new one on that motor, if it worked on the new one, I'd use it. But it looks like it won't.

[Guest]

The 2.8L timing chain is much heavier & brand new. I thought the '99 and earlier chains were better to have, and since I have a brand new one on that motor, if it worked on the new one, I'd use it. But it looks like it won't.

It seems GM finally figured out the timing chains when they got to the LX9. While the older chain is indeed thicker, I'm not convinced it's any better than the LX9 chain.

In my experience the older chains stretched very quickly, where as the LX9 chains don't seem to have this property. My LX9 is supposed to have 199 000 km on it and the chain, which I assume is stock was still quite tight.

[Ghosteh]

I'm probably overthinking things and making them more difficult than they have to be.

You're correct; the stock LX9 chain should be fine, and I should just get a new one rather than trying to use something that doesn't fit. I'm not building a top-fuel dragster here.

I did find this thread where they mentioned swapping the internal chain tensioners with the external tensioner from the 3900. According to the thread, it may not help with stretch, but should prevent chain-slap. For $22, it would be a very cheap addition. Thoughts?

http://60degreev6.com/forum/showthread.php/51458-RWD-Double-Roller-Timing-Chain

[3400-95-Modified]

I not a fan of the LX9 chains... with a Milzy Stage 2 cam and LS6 springs this was 15k miles... IF that many...

Tight on one side VERY loose on the other.


Comparison 94-99 3100/3400 chain vs the new 2000+ 3400/3500 chains.


The one image your missing from above... this is the chain that was after the 2.8/3.1 version but before the LX9, so the pre 2000 LA1 and L82 engines.


I've been through many timing sets trying to find a good combo...

http://60degreev6.com/forum/showthread.php/43914-Timing-Sets?highlight=timing+chain

Right now I'm running a Advance Auto replacement chain with OEM GM sprockets...(94-99 3x00 Version) Seems to be working and a full GM setup lasted about 2-3 years for me. I hope to one day trust the DRTC setup that I bought since my first run with that didn't work out quite well as some know. BUT until I hear slack on the setup that's currently in there I'm not touching it.

I have the tensioner you posted about.... I still need to see if that will work/help with a 94-99 style chain setup because if it does I'm putting it in my car.

[Superdave]

My stock LX9 chain had 678 miles on it, installed on to my custom cam and ran for a few thousand miles. Was stretched enough to replace the next time I had it apart.

I used a whole GM timing set for a '99 3100 and never had another problem. From what i remember the 99 and older sets use the Gen 2 chain and lower crank gear, just the different cam gear.

[3400-95-Modified]

That is correct Dave.

[caffeine]

I think they may have beefed up the stock chain later in the 3500's production run as both Mars and I have run stock chains in our 3500s. Mars had a timing related failure but it was the cam dowel that was the problem.

[3400-95-Modified]

I had an 04 3500 that I used the chain from. I also daily drove this car with the Milzy cam and springs.

I mean run what you want but with all my experience I will always use GM sprockets and preferably a GM chain, currently this SA Gear one has held up good.

And someday I hope to have enough trust to put the DRTC back in for a try.

[caffeine]

Ya all my 3500s have been '06s except for one '05 which also has a cast iron crank

[3400-95-Modified]

It's the same timing chain on GM's website from 03 3.1's up to 06 3.5 VVT's... so unless there was a PN change during 06 that served as an alternate for replacement parts then I doubt there is anything different.

[Ghosteh]

Correct me if I'm wrong on this guys. I've been reading several different threads that have been written here, as well as other sources.
I obviously don't know what I'm talking about, but I'm trying to read & summarize the collective knowledge and experiences here on this issue. I really only want to buy a timing chain once.

The consensus seems to be that running the OEM LX9 timing gears & chain on a modified engine will almost always result in premature wear. Caffeine & Mars must have just gotten lucky and found good ones for their builds.

The aftermarket timing sets without the GM sprockets are not worth bothering with, correct? And the aftermarket set WITH the GM sprockets seem to be ok, but the jury is still out.

The LX9 chain was re-designed to run quieter than the old version. They apparently made it slimmer because it just didn't need to be so beefy with the stock configuration.

With what Dave & 3400 mentioned, it sounds like the OEM LX9 chain is a "hit or miss" item, when using an aftermarket cam & lifter springs. I'm sure with the stock setup, that chain would be fine, but it makes sense that we're taxing it when we start modifying.

So the answer? Early version, stock GM thicker chains & sprockets for modified motors. The '99 3100 is the right chain & crank sprocket, but the cam sprocket is wrong. The LA1 and L82 engines would be the correct set that would bolt-on.

Sheesh! Makes me wish I could just slap on a gear-drive! lol!

[1988GTU]

With the slight upgrade springs and minimal bump up in cam profile, I would:

Buy GM lx9 gears and chain, 3900 guide, send the chain out for cryo treatment.

OR

Buy the DRTC set, have motor fitted and give it a go.

Soon enough I will be running aforementioned DRTC in a lx9. Going balls to the wall or bustin the nuts up fast...