Timing Chain

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Dan the man

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I was doing some reading a little bit ago on the 318's and it suggested that a "true " double roller timing chain be used. I have to admit that I'm confused here as I've always thought that the double roller timing chain were "true " double rollers. Also it said to use a cam as close to the 340 cam as possible, does this include all of the specs of the cam or just the lift and duration at 0.050"? Thanks everyone for your patience. I'm working on asking my questions in a different manner rather than making it sound like I've had some experience with the topic.
 
a "true" roller has pins or "rollers" that well, roll (or spin, if you fancy that term) separate from the outer link, so they "roll" over the teeth of the timing gears. other, more common style is called a "fixed roller" or "fixed link".

you can get both in single or dual links.

the benefit is less friction and double "true" rollers are generally a little bit better made.

cam selection is entirely dependent on many factors of the engine itself as well as intended use. but the recommendation of going with a 340 cam probably indicates all of the specs be close or similar. of course you could start with the 340 cam as a baseline and then tailor aspects of it to your engine and combination-- but that's a whole 'nother ball of wax.
 
Dan the man said:
I was doing some reading a little bit ago on the 318's and it suggested that a "true " double roller timing chain be used. I have to admit that I'm confused here as I've always thought that the double roller timing chain were "true " double rollers. Also it said to use a cam as close to the 340 cam as possible, does this include all of the specs of the cam or just the lift and duration at 0.050"? Thanks everyone for your patience. I'm working on asking my questions in a different manner rather than making it sound like I've had some experience with the topic.
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I like this true roller double roller... I've been using it on my builds for decades and they always hold up well... I rebuild an engine that I had one with 130,000 miles and the chain was still good, I replaced it anyway because I bought another one for only $50 back then...
 
A 340 cam does work great in a 273, 318, and came from the factory in all 340's and high performance 360s. A cam has so much to do with how your engine runs, I would always recommend calling a couple cam companies and talk to them. You need to be honest with yourself and all the particulars of your car if you want a good outcome.
 
I don't think there was such a thing as "untrue" double rollers before the chinese came along.
 
As in this picture, I am holding the chain with a needle nose pliers and twisting the chain. Although this was advertised as a "double roller chain" indeed it is not. A true roller chain would have barrels that would roll within the chain itself. A bicycle chain if you care to look is a good example of a "true roller chain".

IMG_4672.JPG
 
66fs said:
There are also split rollers and solid rollers, .200 OD rollers and .250 rollers. Not as simple as it once was.
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A lot of great information as always. You guys are awesome. Thanks so much for the info. I've noticed since I've taken a better approach on asking questions and such that the replies are great.
 
krazykuda said:
I like this true roller double roller... I've been using it on my builds for decades and they always hold up well... I rebuild an engine that I had one with 130,000 miles and the chain was still good, I replaced it anyway because I bought another one for only $50 back then...
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Dan the man said:
A lot of great information as always. You guys are awesome. Thanks so much for the info. I've noticed since I've taken a better approach on asking questions and such that the replies are great.
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I forgot to post the link...

 
66fs said:
Cloyes had both. The True roller was a premium set with stronger chain links and hardened billet sprockets if I remember correctly.
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Cloyes may have had one of the original "true roller" timing chains in part # 9-3103 for Mopar small blocks. I've used them almost exclusively for decades & I believe they were sold under the Direct Connection/Mopar Performance label as well. I believe they have discontinued the old number and now have a true roller with a billet upper sprocket. (The Summit "true roller" looks suspiciously like the original Cloyes!) Milodon makes a good timing chain too.

Besides their different "levels" of timing chains, a cool option with the Cloyes true rollers is that they had and still have sets that are .005" & .010" shorter to compensate for line boring which can move the crank & cam centerlines closer together. Otherwise you can end up with a loose chain. Replacement chain-only are also available.
 
junkyardhero said:
that's what a timing chain tensioner is for! :p
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If I knew how, I would have photo-shopped "Timing Chain Tensioner" in place of BAND-AID.:)

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Tensioners have their place, especially for high mileage applications. But adding friction and wear, however small, doesn't sound like a good idea.
 
junkyardhero said:
depends on who you ask
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I understand. I've gotten so many different answers on them that I think that I'll avoid them. I have those 2 A bodies to check out soon and I'm planning on buying one of them and doing a mild cam upgrade sometime over the winter
 
Dan the man said:
I understand. I've gotten so many different answers on them that I think that I'll avoid them. I have those 2 A bodies to check out soon and I'm planning on buying one of them and doing a mild cam upgrade sometime over the winter
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Because the cam to crank centerline is further apart on the SBM (further apart than a B or an RB) I always used a tensioner.

Is there extra friction there? Sure. Buy a better oil.

And think of it this way. Does the increased friction cost more power than wonky cam timing? I suggest it does not. That little bit of friction is a cheap price to pay for accurate timing.

Of course, if you are that concerned with accurate cam timing you need a fixed idler gear drive. Unless you find one used you won’t get one for a price anywhere near what a TC&G cost.

I eat the cost and use a gear drive. I’m a buy once, cry once kind of guy.
 
please stop with the uninformed nonsense about the timing chain tensioner.
the tensioner provides rock solid ignition timing and keeps the cam events from running "late"
extra friction is more like hot air from the uninformed
 
SixPaksRule said:
please stop with the uninformed nonsense about the timing chain tensioner.
the tensioner provides rock solid ignition timing and keeps the cam events from running "late"
extra friction is more like hot air from the uninformed
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The tensioners were designed for 3.9 v6 engines that had chain rattle issues. From what I have seen, the stock timing set was steel gears and a standard chain. You don't need a tensioner with a good quality double roller. The nylon rubbing blocks on the tensioners are too narrow and not designed for a wide double roller chain.
 
toolmanmike said:
The tensioners were designed for 3.9 v6 engines that had chain rattle issues. From what I have seen, the stock timing set was steel gears and a standard chain. You don't need a tensioner with a good quality double roller. The nylon rubbing blocks on the tensioners are too narrow and not designed for a wide double roller chain.
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I used to think that but virtu every engine I take apart the chain is junk. I just throw a tensioner on it and send it back out.

Ive seen SBC TC&G be shot in under a couple of thousand miles.
 
Like I said, tensioners have their place. It's not always possible to get a proper fitting, tight chain, and gear drives aren't legal in some classes. I'm also looking at it from a strictly race perspective. Just another part that can wear/break and any reduction in friction or wear is a plus even if the results aren't seen. As long as there are no negatives. I thought that the Cloyes options were a pretty good idea, worth sharing to some who may not have been aware of it.
 
I will try to put this nicely, but, planning a cam swap on an unknown-to-you engine that’s in a car you don’t own yet is putting the cart a looooong way before the horse.

Your new engine may already have a cam in it. Or your new engine may be a 7.5:1 compression factory dud that can barely support the stock cam in its current configuration. Or maybe your new car ends up needing $1k in brake and suspension work you didn’t realize until you put some miles on it and a cam change isn’t in the budget anymore.

Doing some research ahead of time is good, planning upgrades on a car you don’t own before you know it’s other needs is silly. And no matter how nice the car is or how well you check it out, you will find things that need to be addressed after you bring it home. Needless to say, what those things are will be specific to the car you bring home.

True double rollers are great, but if I bought a new to me Mopar with a 318 and it ran decent the timing chain wouldn’t be my first concern. Hell the cam wouldn’t be either. Drive it, check more things than any seller is gonna let you check, drive it awhile more, check more things, then maybe start planning upgrades.
 
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