Don't overthink it. If it's a total effort deal then use the best there is.

 

So I take it everyone's of the opinion the loose chain is normal. Well I have double roller on my LSX and it wasn't loose like that so you have something going on there you may want to look into.

 

"That "test" proved absolutely nothing."

I agree, the test was not intended to prove anything.

Interpreting the video may be subjective but valid regardless.

My feeling is it's too weak.

 

I wouldn't say it's normal for a new chain, I've changed quite a few, Just did one a couple weeks back and the old chain was that loose but not the new one. The new chain basically had virtually no slack just as I expected.

 

I'm running that cam in my LS1, the ONLY thing I changed was the cam and springs. I left the stock chain, gear, everything. I'm not worried at all and I shift mine at 6800

Thanks stockA4
I don't think I'm game to go past 6500 as I have a 99 LS1 they had the weaker rod bolts.

 

The chain needs to be loose because the aluminum block expands a lot more when it heats up than an iron block does. There are a lot of discussions on here about this. If the chain starts out tight on a cold engine, then it will be too tight at operating temp, causing cam bearing wear.

 

I guess I should have watched the whole video, The part I watched showed a very slack chain, I didn't realize if you continued to watch the chain tightened back up as it was turned part of a revolution. One gear or the other is offset and it's most likely the cam gear.

Cam tension....If it's as tight as a banjo string your probably going to have a problem regardless, If you can deflect it 1/8" you're good to go with either block material. Your always going to have some deflection as soon as the chain and gears break in. As far as aluminum block growth is concerned I've always been told it was twice that of an iron block but when you're measuring in thousandths of an inch its still not enough to be concerned about when it comes to timing chain tension. I try to use RollMaster/IWIS chains on any engine because they have proven to be a quality part.
If you line bore you can use this guide for the proper gear/chain combination. Rollmaster:How to Determine Tunnel Bore Sizes

 

Thanks for that info much appreciated! Also

"One gear or the other is offset and it's most likely the cam gear"

Do you think cam or crankshaft bearing wear or wide tolerances could cause it to tighten and loosen when turned rather than cam gear being offset?
Regards Tim

 

Not likely but It will be easy to figure out, Remove the chain if possible and make a pointer out of a coat hanger, bend the hanger until it's close but not touching the gear and then turn the gear and watch for the gap to increase or decrease.
The same can be done with the crank snout by and the cam if you remove the gears.

 

First of all, Impact testing is not a random guy with a hammer out in his garage banging on metal. There is an ASME code that defines the controlled variables, such as the cross section and temperature of the specimen. Your "test" tells almost nothing about the mechanical properties of this metal.

With that said, you're hitting the cam gear and breaking it where it's thinnest. The cam gear is not meant to sustain shock loads along that axis. It's designed to sustain loads along a perpendicular axis.

The fact is that these OEM gears have been used in pretty rigorous applications, with dual springs and high RPM, and the gear itself almost never breaks. The aftermarket sets have advantages in being adjustable and providing an extra row of chain, but that's about it.

 

If you don't want to go to 6800+ you should be looking at the summit 8713 then, that rod bolt thing is really a crapshoot

 

Don't forget that a new chain should (theoretically) be tighter than a used chain. My mechanic has shown me several timing chains that have stretched as the miles increase.

 

Quote. "If you don't want to go to 6800+ you should be looking at the summit 8713"

​​​​​​The 8713 only has 1 degree more intake duration than my current cam, the 8714 has a little more overlap too although I might end up advancing it 4 to 6 degrees when installing it, the overlap will still give it a nicer idle than my current cam even if duration ends up exactly same, not sure which way to go yet. My main goal was to get a nicer idle and hold on to peak power longer for better quarter times my BTR 219/224+3 113 truck cam in my LS1 drops hp like a stone after 5900 rpm and hits it's peak power at 5650 rpm ( a mere 250rpm window) its not unusual to see cams hold on to power for 1000 rpm past peak or more. This is what I'm wanting.

 

Check out my thread in the 11 sec club, I made the exact same cam swap, not for idle but, et. I'm surprised you didn't get more rpm from that cam, I shifted mine at 67-6800 for my best et's and it peaked at 6300/4800 like it should with the rest of my setup. I'd get a good wideband street tune on the car before I changed anything else

 

Better change the glass on your car to lexan, glass can't stand up against a pebble. Just imagine what would happen if it met a hammer.


If you did a test on the glass with your car with a hammer, it would have the same merit this test did. Neither item sees shock loads, nor was it designed to. If things not standing up to a hammer bothers you, you're gonna be changing a LOT of parts on the car.

One thing that will shatter the cam gear or oil pump gear is harmonic vibrations, so the billet set may stand up to that better, but you'll have other parts of the engine hanging out of the oil pan most likely if the vibrations are that bad, you're timing chain may be re usable though.

 

Good idea as windscreens sometimes break from impact although its hard to make Lexan scratch resistant enough to be viable to replace glass. I'm sure if they could make an almost unbreakable glass for cars cost effectively they would. So a compromise is struck.

Timing gear on the other hand can be made out of a billet of Heat treated carbon steel with both the properties of higher impact resistance and high wear resistance as they almost always are when aftermarket dual or single row billets are used for little additional cost to deal with the additional stress loads. So there is no compromise needed.

Sintered powdered metal often fails in some engines when it is used for the oil drive gear along the centreline of the keyway and also the internal parts of the common M295HV oil pump are sintered powdered metal (& many others) and can and do break if not installed centred correctly with high rpm use (are these subject to impact?). Even if the camshaft sprocket is made from powdered metal or ductile iron the crankshaft timing sprocket is usually made from HC heat treated steel as it is recognised this area needs the extra strength and possibly extra wear resistance also, it surprises me then that the pump drive and internal part of most oil pumps are often not made of the same HC material hence they break more often.

Brittleness and strength are related (ie, if it is brittle it's likely to have other non desirable characteristics in some applications)
https://www.sciencedirect.com/topics/materials-science/brittleness
Just to be clear I'm not concerned about my powdered metal timing gear in my LS1 breaking it was just a bit of cheap fun, although it did make me wonder a little how weak the chain may have been for a $35 set. But then I am running low lift, rpm and spring pressure, so no need for concern.

Oil pump
https://ls1tech.com/forums/generation-iv-internal-engine/1641885-wtf-how-do-you-break-oil-pump.html

 

If you see a oil pump gear break at high RPM, look at the balancer. Every time I have seen that it was due to harmonics

 

My Melling m295 came with instructions that said to centre it with spacers as done in above link if it was to be used for high rpm.

 

They really should be centered regardless but a lot of people just throw them on and they are fine. I have done that plenty of times myself and never had an issue.

There's a shimming process where you take the front cover off and center the housing using shims between the housing and the rotor. It's fairly well known about around here.

 

Did a bit of a search on it, this is what I found