LS3 timing chain tensioners: differences?
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LS3 timing chain tensioners: differences? I see that the PN 12585997 tensioner has been superseded by 12626407. Does anyone know if the new PN tensioner is any different? I'm curious if it has changes to address the failures people have seen. Also wondering if other tensioners have been introduced recently for the latest LS3, L99, etc.
Not interested in an LS2 damper vs. LS3 tensioner debate in this thread. Just curious if there are variants of the LS3 tensioner that I should be aware of. I read rumors that there was a change in tensioners in '09, but I don't know what the change was. I also can't find a parts diagram online anywhere showing the GM part number for the tensioner.
Not interested in an LS2 damper vs. LS3 tensioner debate in this thread. Just curious if there are variants of the LS3 tensioner that I should be aware of. I read rumors that there was a change in tensioners in '09, but I don't know what the change was. I also can't find a parts diagram online anywhere showing the GM part number for the tensioner.
Last edited by -TheBandit-; Oct 30, 2012 at 01:11 PM.
Thread Starter
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From: Instagram @chevyhotrodder
If a tensioner is needed is a debate for another thread, but the short summary is: early LSx engines had no tensioner, then the damper was introduced, then the spring tensioner was introduced.
the reason I ask, I am building an LS3 right now and with the failures reported with the spring tensioner would it be more wise to not use it at all? This goes along with the same question you are asking, I have read of failures with both part #s
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From: Instagram @chevyhotrodder
That topic has been discussed a lot elsewhere. Should be easy to find discussion in another thread. I am specifically interested in the differences between these PNs and whether or not any new/different tensioners have come out.
Most guys change to the LS2 type damper instead of using the spring loaded tensioner
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Sorry Clint, you just can't keep people from repeating Internet Gossip.. Single bolt cam gears, like the VVT system, have to use the tensioner.
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Sorry Clint, you just can't keep people from repeating Internet Gossip.. Single bolt cam gears, like the VVT system, have to use the tensioner.
Sorry Clint, you just can't keep people from repeating Internet Gossip.. Single bolt cam gears, like the VVT system, have to use the tensioner.
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Thread Starter
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From: Instagram @chevyhotrodder
It does appear many have the opinion that the LS2 damper is more reliable and there are certainly cases reported of LS3 tensioners failing. However there are also cases of timing chains breaking with either tensioner. There are cases where people prefer carburetors. There are cases where complex is not better than simple. I wasn't asking that question in this thread. I was really hoping to avoid the tensioner vs damper debate altogether.
What I really want to know is if there is a new, improved, or revised design tensioner available - either with new materials, new design, or something different that might make it more reliable than the original LS3 tensioner. I am very curious if the -407 PN tensioner uses a different kind of plastic, different heat treat on the leaf spring, or other improvement.
The new LT1 looks like it has a similar tensioner design. Maybe it will be better and maybe it will be interchangeable with the gen III/IV.
What I really want to know is if there is a new, improved, or revised design tensioner available - either with new materials, new design, or something different that might make it more reliable than the original LS3 tensioner. I am very curious if the -407 PN tensioner uses a different kind of plastic, different heat treat on the leaf spring, or other improvement.
The new LT1 looks like it has a similar tensioner design. Maybe it will be better and maybe it will be interchangeable with the gen III/IV.
It does appear many have the opinion that the LS2 damper is more reliable and there are certainly cases reported of LS3 tensioners failing. However there are also cases of timing chains breaking with either tensioner. There are cases where people prefer carburetors. There are cases where complex is not better than simple. I wasn't asking that question in this thread. I was really hoping to avoid the tensioner vs damper debate altogether.
What I really want to know is if there is a new, improved, or revised design tensioner available - either with new materials, new design, or something different that might make it more reliable than the original LS3 tensioner. I am very curious if the -407 PN tensioner uses a different kind of plastic, different heat treat on the leaf spring, or other improvement.
The new LT1 looks like it has a similar tensioner design. Maybe it will be better and maybe it will be interchangeable with the gen III/IV.
What I really want to know is if there is a new, improved, or revised design tensioner available - either with new materials, new design, or something different that might make it more reliable than the original LS3 tensioner. I am very curious if the -407 PN tensioner uses a different kind of plastic, different heat treat on the leaf spring, or other improvement.
The new LT1 looks like it has a similar tensioner design. Maybe it will be better and maybe it will be interchangeable with the gen III/IV.
As far as the Gen V goes, I can see it going either way. In many ways it is pretty obvious that they simply expanded on the successful Gen IV design, but they did it in a fairly serious and meaningful manner and I can see where there would be benefits to improving the tensioner design.
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From: Adelaide, Australia
Simply replacing the stock tensioner assembly with an LS2 damper will not heed any advantage or contribute to reducing chain failure risk.
The solution is a Cloyes Billet set, these feature 'oversized' cam & crank gears that eliminate the slack found in stock chains and other aftermarket sets.
Adding an LS2 damper in this case is advisable as it prevents the chain whipping back under rapid deceleration - the main cause of chain failure.
The solution is a Cloyes Billet set, these feature 'oversized' cam & crank gears that eliminate the slack found in stock chains and other aftermarket sets.
Adding an LS2 damper in this case is advisable as it prevents the chain whipping back under rapid deceleration - the main cause of chain failure.
Teching In
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The chain pitch is the same as stock as the increase in sprocket size is insignificant to necessitate a change but enough to take up the slack found in the stock and other aftermarket setups.
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Does the tighter chain make it hard to get the cam gear on?
I do like the easy cam degree adjustment!
I know Cloyes is highly regarded for SBC and other parts; and a Tier 1 auto supplier.
IIRC, Cloyes makes an SBC cam gear cover with a removable plate for accessing the adjustable cam gear bolts. That would be cool for LS engines too.
I do like the easy cam degree adjustment!
I know Cloyes is highly regarded for SBC and other parts; and a Tier 1 auto supplier.
IIRC, Cloyes makes an SBC cam gear cover with a removable plate for accessing the adjustable cam gear bolts. That would be cool for LS engines too.
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From: Instagram @chevyhotrodder
That's a nice little upgrade. I hate the slack in my factory chain, though I have to think the factory had a reason (noise? manufacturing tolerances?). It'd be cool if a belt drive fit behind the oil pump, but I think those are limited to dry sump setups.
In the VVT world, we don't have many options. I am doing the factory sprockets & spring tensioner with the "C5.R" chain.
In the VVT world, we don't have many options. I am doing the factory sprockets & spring tensioner with the "C5.R" chain.