Timing Chain

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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.
Your right. So far from what information I have on the car the engine is in good condition. But I totally understand what you're saying and I truly appreciate your comments
 
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.

I disagree...

If it's a virgin 273/318 with the facory nylon tooth timing gear and chain, the first thing to do is replace it with a double roller of any kind, preferably a true roller double roller...

The stock factory chains are junk, the nylon gets hard and chips off the teeth, making the chain loose and in some cases can jump a tooth...

My first 318 barracuda had 84 k original miles and when I replaced the stock chain and gears with a double roller and increased mileage by 2 MPG....

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I've seen original 340 double roller chains still within spec with over 100,000 miles on them. I have used an old Cloyes true roller from one engine to another. I got the tensioner bug, a while back but when I thought about it, I'm not going to use it. I have a 273 with 300,000 miles on it with a 340 double roller timing set in it. That engine starts and runs like new. Anybody want a new tensioner cheap?
 
I disagree...

If it's a virgin 273/318 with the facory nylon tooth timing gear and chain, the first thing to do is replace it with a double roller of any kind, preferably a true roller double roller...

The stock factory chains are junk, the nylon gets hard and chips off the teeth, making the chain loose and in some cases can jump a tooth...

My first 318 barracuda had 84 k original miles and when I replaced the stock chain and gears with a double roller and increased mileage by 2 MPG....

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Hey disagree all you want, I don’t care.

But if I got a sub 100k mile 318, and it ran decent, the timing chain still wouldn’t be on my top ten list of things to check/worry about. It would definitely be on my list because you’re right, the original nylon coated timing gears are lame. But unless it presented with an actual timing issue, it still wouldn’t be my first concern. Obviously if it did present with a timing issue that would be one of the first things I checked after the distributor.

And realistically, how many of those original timing gears are out there anyway? I know that they are out there, but sub 100k original mile 318 engines aren’t something you see everyday. Hell even some of those have probably had timing chains replaced.
 
I've seen original 340 double roller chains still within spec with over 100,000 miles on them. I have used an old Cloyes true roller from one engine to another. I got the tensioner bug, a while back but when I thought about it, I'm not going to use it. I have a 273 with 300,000 miles on it with a 340 double roller timing set in it. That engine starts and runs like new. Anybody want a new tensioner cheap?
I put a tensioner on my 273 when I built it just because it was the cool thing to do. Not needed with a good double roller.

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Since on the subject I’m actually removing my timing chain as we speak, removing the upper gear what’s the best way? Just pulled the motor yesterday. Going to re hone it rings and bearings to get it running. Thanks

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Since on the subject I’m actually removing my timing chain as we speak, removing the upper gear what’s the best way? Just pulled the motor yesterday. Going to re hone it rings and bearings to get it running. Thanks

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How bad is the ridge at the top of the bore? Sometimes it takes a ridge reamer to remove it, if the ridge is to much you'd be better off having it bored and yes I'm speaking from experience on this one.
 
There's a long thing in the /6 part of the forum about using/not using a ridge reamer (banging head)
 
I put a tensioner on my 273 when I built it just because it was the cool thing to do. Not needed with a good double roller.

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I've heard some people say you can't use a tensioner with a double roller because the chain will chew it up, but then some people say no...

How's yours working out???
 
Hey disagree all you want, I don’t care.

But if I got a sub 100k mile 318, and it ran decent, the timing chain still wouldn’t be on my top ten list of things to check/worry about. It would definitely be on my list because you’re right, the original nylon coated timing gears are lame. But unless it presented with an actual timing issue, it still wouldn’t be my first concern. Obviously if it did present with a timing issue that would be one of the first things I checked after the distributor.

And realistically, how many of those original timing gears are out there anyway? I know that they are out there, but sub 100k original mile 318 engines aren’t something you see everyday. Hell even some of those have probably had timing chains replaced.

I'm not going to tell you what to do with your engine, it's YOUR engine...

That's what I do with mine...

And yes, there are very few of the original timing chains left, but if I have an engine with one - it's getting replaced with a double roller ASAP!!! The increase in MPG will pay for the chain soon enough...
 
There's a long thing in the /6 part of the forum about using/not using a ridge reamer (banging head)
I've seen the ridge break the top ring land of pistons before. If you have a high mileage small block your better off having it bored, you don't want to rering a block with a lot of cylinder taper as the rings will not seat
 
:rofl:
Oh boy, nothing like putting out a fire with a bucket of gas! :poke:

But the thread has run it's course will all opinions represented.
 
Most newer designed engines that use a timing chain also have a tensioner designed in to keep tension on the chain. Even motors from the 60’s like the Jag 4.2 straight 6 had a tensioner from the factory. My Kawi ZX6-R that revs to 17,000 has a timing chain tensioner from the factory…. It’s used for a reason… so to each their own..
 
When I see conflicting opinions from guys with real world experience, it usually means it doesn't matter and they are both right. :)
 
Most newer designed engines that use a timing chain also have a tensioner designed in to keep tension on the chain. Even motors from the 60’s like the Jag 4.2 straight 6 had a tensioner from the factory. My Kawi ZX6-R that revs to 17,000 has a timing chain tensioner from the factory…. It’s used for a reason… so to each their own..

Just because tensioners work/are needed in other applications doesn’t prove you need a factory designed tensioner on an LA engine.

The need for, and the functionality of, a tensioner are completely dependent on the design of the engine and the tensioner. Lots of newer engines have multicam systems too, and longer timing chains/belts, which makes a tensioner(s) much more necessary.

Just because your Kawi has a tensioner and it revs to 17k doesn’t mean you need a tensioner on an LA, or the that an LA tensioner is capable of revs anywhere near that.
 
Just because tensioners work/are needed in other applications doesn’t prove you need a factory designed tensioner on an LA engine.

The need for, and the functionality of, a tensioner are completely dependent on the design of the engine and the tensioner. Lots of newer engines have multicam systems too, and longer timing chains/belts, which makes a tensioner(s) much more necessary.

Just because your Kawi has a tensioner and it revs to 17k doesn’t mean you need a tensioner on an LA, or the that an LA tensioner is capable of revs anywhere near that.
I don’t disagree. The real issue is that the quality of most chains produced today is not great and they stretch, thus causing other issues like timing jumping around due to the “whip” of the chain. I went down this rabbit hole 2 years ago. We tried 5 different timing lights, 2 different distributors that were ran on the test machine, changed out the MSD and coil, all came back with the same issue of the timing jumping around. Then did surgery, pulled the cover and found that the chain had a ton of slop on the driven side. Oh yeah, it’s was a Cloyes true roller chain with like 20 hours on it. Changed it to the pro gear I posted above. The timing issue was then corrected..
 
What side of the chain do those tensioners work on? If the "downwind"(following) side it will pull the cam timing "retarded" and will retard cam timing worse than if the chain slip was allowed to "float". Though it will hold it more consistent and not "bounce"as the chain does wear.
I have a problem with all of the new fangled engines, many with multiple chains even.
I never thought a steel chain scraping/constantly rubbing a plastic guide was ever a good idea.
For the same reasons as brought up about nylon coated cam gears becoming brittle and chipping and breaking with heat/cold cycles it's like your building something you want to fail.
I begrudgingly have 2 4.7 equipped vehicles in the driveway, gritting my teeth dreading the day the timing system fails on both of them,
There should have been laws forbidding the big 3 from phasing out their tried and true small blocks. I so wish I could have gotten both of these vehicles with 318/360 magnums instead.
 
Most newer designed engines that use a timing chain also have a tensioner designed in to keep tension on the chain. Even motors from the 60’s like the Jag 4.2 straight 6 had a tensioner from the factory. My Kawi ZX6-R that revs to 17,000 has a timing chain tensioner from the factory…. It’s used for a reason… so to each their own..
here's the key: those engines were designed with the tensioner incorporated into them. the components are specifically built and spec'd out to work together.

the part that gets glossed over in the whole argle-bargle of tensioners is that people were installing them with chains that were not compatible-- ie too wide, wrong link spec, not finish machined; and the chains would absolutely destroy them in short order. OR they were installing them as a bandaid fix for cheap *** chains, clapped out stretched units, or incorrectly.

there's nothing inherently wrong with a chain tensioner that is engineered and designed within the architecture of a motor, it's when they're used as a secondary thought to correct a problem that could be corrected by using better parts from the get go. also, tensioners are wear items, a lot of people seem to forget that and act all surprised when they need to be replaced.
 
What side of the chain do those tensioners work on? If the "downwind"(following) side it will pull the cam timing "retarded" and will retard cam timing worse than if the chain slip was allowed to "float". Though it will hold it more consistent and not "bounce"as the chain does wear.
I have a problem with all of the new fangled engines, many with multiple chains even.
I never thought a steel chain scraping/constantly rubbing a plastic guide was ever a good idea.
For the same reasons as brought up about nylon coated cam gears becoming brittle and chipping and breaking with heat/cold cycles it's like your building something you want to fail.
I begrudgingly have 2 4.7 equipped vehicles in the driveway, gritting my teeth dreading the day the timing system fails on both of them,
There should have been laws forbidding the big 3 from phasing out their tried and true small blocks. I so wish I could have gotten both of these vehicles with 318/360 magnums instead.

That’s why you degree the cam with the tensioner on.
 
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