do chains really stretch?

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pishta

pishta

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Opinion: Do double roller chains stretch or do the cogs wear? I see hardened cogs from OZ and I see super duty chains too, so what wears? I just took a stock timing chain out of a hi-mile 318 and it could have hit the side of the cover it was so loose. CAT GD-318 gear drives are 150 all of a sudden? Like 'em or not, they were a deal at $79.00...
 
First, "stretch" is a misnomer. The slack is only slightly due to metal stretch (or bending). I think both the teeth wear and the rollers and link pivot holes wear. That is why you should change both chain and sprockets. I am always amazed how tight a new timing set goes on. It seems like it won't fit, but it always barely does. I have read of people having engines that need a custom set, usually shorter than stock, because of custom-grinding of the main bearings or such.
 
was wondering that myself, just bought a Comp Cam kit and was thinking of installing 4 degrees advanced just for this issue.
 
We have had great luck with the Aussie "Roll Master" IIRC. Jezz, been awhile since I've done one. Otherwise, do a gear drive.
 
berlins said:
was wondering that myself, just bought a Comp Cam kit and was thinking of installing 4 degrees advanced just for this issue.
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I installed the set in my 273 at the 4 deg advanced setting. That is supposed to give better low-end torque and better mileage, plus should allow for wear over time, as you suggest.

I went further and installed an "RV torquer" hydraulic cam (.422/.440 valve lift) and Rhoads leak-down lifters. Not daily driving the Dart yet, so can't report mileage, but it seems to idle great and I don't even notice the lifter ticking. I have more planned for the future. Who cares about performance when gas is $5/gal? I want a car I can drive.
 
Chrysler small block has one of the the longest cam to crank centerlines of production V-8's. That why they tend to get looser faster than other V-8's.

I ran a MP timing chain tensioner with my Rollmaster timing chain. We found it changed the cam timing one whole degree! All parts brand new.
 
Hell yeah they stretch. Especially the cheap chinkese junk a lotta people use to try to save money. You need to look for a solid roller (no split rollers) and run the Mopar (Cloyes) timing chain tensioner.
 
Chains stretch, sprockets wear. We used to sell industrial chain and I used to "cheat" and use ??40?? ??50?? industrial chain on my Yamaha 650. When the sprockets get worn, the old chain still looks like it "fits pretty good" but if you try and put new chain on a worn sprocket, you can immediately tell there's a problem.

"Back in the old days" I used to buy name branded Cloyes, etc, and EVEN THOSE stretch a little after a surprisingly small amount of miles. Once when I "went through" a 440, I installed new drive, old stock cam, to break in the engine, then after about 500-1K miles, I changed to a Sig Erson cam. I was surprised that there was now SOME slack in the new cam drive.
 
The tensioner works really good. I think it does it's best job by just that......keeping temsion on the chain even if it is worn. It also helps by engagining a few extra teeth on the sprocket since it pushes in against the chain from the passenger side.
 
I installed a comp chain and gears and after one year it looked like had 80k on it, that is just one of the many reasons i do not used comp products anymore.
 
I thought the comp chain was pretty flimsy looking myself. Maybe I should pull the timing cover and check it out. LOL

Keep in mind, small block Mopar has a really long timing chain compared to some others, that can't be helping the issue.
 
I like that tensioner, are they stock on anything? I see they are for RAM's but it says silent chain...? Seems it would work better if it pushed the chain out rather than in, so the chain whip would not work against the tensioner, but if it works, it works. Stroker, who makes that solid roller? Rollmaster, ProGear? How about a pre-stretched? curious hearing these stories of 500-1000m chains that are already flabby.
 
65Vsignet said:
I installed a comp chain and gears and after one year it looked like had 80k on it, that is just one of the many reasons i do not used comp products anymore.
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You're going to find a lot of brand chains that do that. Inherent problems.

Thats one of the reasons Mopar designed tensioners to put on the production small blocks.
 
I got mine from Summit. Both Cloyes numbers.

Tensioner 9-5387

Chain 9-1103
 
I like that tensioner, are they stock on anything?

I think they are stock on 3.9L Dakotas. IIRC, that's the application I bought for when I got mine.
C
 
Tensioner is a no brainer. It's beneficial,period and no drawback's I know of.
 
I hate to break it to you but chains don't stretch unless they're damn close to breaking.

Think: If the metal is under enough tension to cause it to stretch, when would it stop stretching?...well, it wouldn't, until it broke.

Chain "stretch" is wear between the rollers and the pins, and the pins and the links. A new chain is nice n' tight like your sweetest high school memories, but because very few chain manufacturers will take the time (and because you won't take the dough) to polish-fit each pin, and each link-hole, the pins and holes burnish in giving you the initial "stretch".

The sprockets (not "gears" in a chain-drive setup) don't wear much at all.
Think: Rollers. They're stationary when they're riding round the sprocket. The rolling is in between the roller and pin. This is why modern motorcycles use o-ring chains; to keep the lube in and dirt out of rollers and pins.

As the wear commences, the centerlines of the pins grow further apart, and this causes the chain to contact the leading or trailing edge of the sprocket tooth where it has minimal contact area so the loading is very high. When it's new, the chain rides in the valley of the tooth where there's tons of contact area and the load is spread out.

So the sprocket essentially gets hammered out of shape over time, not worn, because the rollers are no longer hitting where they're supposed to. The teeth actually grow in length as they're hammered to be thinner in profile. And your new chain doesn't get guided to the valley of the tooth on the worn sprockets...so your new chain gets "hammered" to match the old sprocket, in short (and expensive) order.

Not that it matters one bit, but I've replaced a billion motorcycle chains n' sprockets in my life (and a few timing chains, too), and the vernacular is mis-leading. Correct answer: During normal wear the chain does not stretch and the sprockets do not wear. The chain wears and the sprocket gets hammered.

An improperly heat-treated chain can stretch, but usually just a little before it's stretched in two.
 
Yea that's what I was thinking,,stretch= wore out.
 
pishta said:
Opinion: Do double roller chains stretch or do the cogs wear? QUOTE]


It depends on if you are using Cogswell Cogs or Spacely Sprockets. :stop:

Spacely Sprockets last longer... :supz:
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Chains do stretch. That is why they recommend replacing them when there is over 1/2" of play.

Tensioners - I believe that they came on some of the truck engines sometime in the late 80's or early 90's. HemiEd would be a better guy to ask that question. He had a 91 360 that he sold us that had a tensioner on it. I'm not sure if it originally came on our engine or he put it on from another one.
 
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