What's your opinion on the slack in this 318 timing chain?

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67C,
Post #47.
3.6 crank degrees. Sort of.....
One cycle of the engine is 2 revolutions, 720 *. So 1.8* of movement relative to cam & ign timing events.
 
Bewy said:
67C,
Post #47.
3.6 crank degrees. Sort of.....
One cycle of the engine is 2 revolutions, 720 *. So 1.8* of movement relative to cam & ign timing events.
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Yes, I sort of knew that when I posted that. At first I was eyeballing the slack by looking at the crank keyway, but the slack was a fraction (maybe half or less) the width of the keyway. When you look at adjustable crank sprockets and how far apart they put the keyways they're quite far apart (relatively speaking) so any timing slack that is less than the width of the keyway turns out to be pretty small (degree-wise).
 
I see a lot of people fretting over timing chain slack on cam in block engines (OHC is entirely different.)
I personally think this mindset is a byproduct of the plastic top sprockets of the 70's that were supposed to quiet engine noise.
Those things were gone in 70K miles. But this is not the 70s and those plastic top sprockets are gone.
I've seen steel top sprockets go 300K without issue.

If it makes you sleep better at night, replace it.
Or put on one of those timing chain tensioners;

Mopar Part No# P5007709​

It's only money.

1724437035341.png


Hey look!
There's slack in this new chain.
 
^^^^ Agree. If you are going to worry about t/chain slack, you will be spending a lot of time replacing t/chains....
 
i was perusing the FSM on an unrelated matter... and guess what? they have the spec listed out right in the print!

with the slack removed and 30 ft/lb of torque on the sprocket bolt there should be no more than 3/16" inch of movement. (15 ft/lb without the heads installed)

1969 FSM 9-33 (diag. NU268)

what is done with this information is entirely up to you.
 
junkyardhero said:
i was perusing the FSM on an unrelated matter... and guess what? they have the spec listed out right in the print!

with the slack removed and 30 ft/lb of torque on the sprocket bolt there should be no more than 3/16" inch of movement. (15 ft/lb without the heads installed)
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I wasn't sure where the measurement was taken, so I had a look at my '67 Dodge Monaco/Polara manual:

timing-chain-check.jpg


So this is different than measuring the slack with a straight edge against the sprockets.

I don't have a cam sprocket handy right now to measure, and I can't find ANYWHERE on the net a spec for the cam sprocket diameter, but assuming the diameter is 6 inches then 3/16 inch is 3.6 degrees. So that's degrees of CAM timing, which would equate to 7 degrees of crank movement. This agrees with at least one youtube video I've seen where the guy is saying the stretch limit is 7 degrees of crank rotation.

According to my manual, this 3/16 inch is the same for the 383/440.
 
If the block was line-honed, the chain will have more slack than stock. But this looks fine. If worried, put a Mopar Perf chain tensioner on it. That will take up all the slack and keep the chain from whipping. Did it on all my 340's.
 
RLF Cuda said:
If the block was line-honed, the chain will have more slack than stock. But this looks fine. If worried, put a Mopar Perf chain tensioner on it. That will take up all the slack and keep the chain from whipping. Did it on all my 340's.
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You would think (or - I would think) that there would be more options for undersized chain sets for the past dozen or more years given the likelyhood of engine rebuilding (and line-honing) would be increasing for these engines.
 
67CBodyGuy said:
You would think (or - I would think) that there would be more options for undersized chain sets for the past dozen or more years given the likelyhood of engine rebuilding (and line-honing) would be increasing for these engines.
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Line honing gets blamed for loose chains but if it’s done correctly it moves the crank very little if at all.
 
318willrun said:
My opinion.... my experience ..... under normal conditions, double roller chains and no nylon sprockets equals couple hundred thousand miles without issues with good, clean oil.
:)
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No question about it, nylon sprocket, change it to a double one, as in the 340's. I had 318's that would jump teeth at around 40,000, but my 340's are still running at 200,000 miles.
 
67CBodyGuy said:
I'm tearing into this because of a coolant leak between the timing cover and the block, otherwise I wouldn't be here. I was curious about the condition of the timing chain. This engine was bought from a Chrysler dealer, it came from an authorized rebuilder in Toronto (Ontario Reman) circa 1986 and I might have 10k miles on it at this point.

View attachment 1716291817

View attachment 1716291818

Sprocket made in Canada? Links made in Japan?

From what I read, even new timing sets have slack, maybe more than some people want or expect. I didn't measure the slack here, I can, but it looks like 5/16 inch. I haven't driven the car much in the past 2 years (was in storage for 20 years before that) but I'd like to see a smoother idle, don't know if it's the crappy gas now, or my expectations of 550 rpm, or the carb setup, or still having points (not electronic) ignition - or this chain?

I'm going to have to decide in the next couple days if this chain is staying on or if I'm going to replace it. Comments?
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Find and watch the David Vizard Powertec 10 video on timing chain tightness. A real snug chain can cost power. Slightly loose may be good for 5 to 10HP. 10k miles, that chain looks OK to me, but if you areconcerned, you should be able to get a replacement chain.
 
ProjectBazza said:
When I checked the slack in Bazza's 318 last summer I ran across a little tidbit of information (here or elsewhere, I don't recall) that said that if there was 5* of "slop" between the timing marks when you rotate it backwards and forwards, it's worn-out. Not sure if that was "By the Book", but I followed it.

And I took a video of this for Bazza as well:



Another way of thinking about this: If there's slack in that chain, how accurate is your timing going to be, and thus, how well is your engine going to run?

Of course you could always just say, "Screw it! I'm already in here, and I may as well take care of it", which is what I would do.
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I worked with a mechanic who would not do a tuneup on an engine with 30k+ miles on the timing set. A bit excessive IMHO, but that was linkbelt chains and nylon cam gears. His claim was you can never get the engine to run properly. I turn the engine back and forth to get an idea of the chain slop. Just do not get carried away and turn the cam. Getting rid of the nylon gear is a good idea. Replace with a reputable true roller set.
A block that has been align honed may need a timing set to compensate, that is designed to take up the shorter cam to crank centerline distance.
With the low mileage and the slop is not bad, I would run it. When running, check timing deviation/scatter with the timing light. A couple of degrees will not hurt how the engine runs or power. A hi perf or race engine is a different conversation.
 
Dartswinger70 said:
It depends if you are going to put the miles on it replace it if its a strip car how many more runs till ya tear it down etc. If one is really worried about timing accuracy go to a gear drive. The chains work and worked well for years...they aren't supposed to be zero slack tight either...that causes other problems.
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Old Vauxhall Epidemics would wear the chain so bad you could hear it slapping on the timing cover. Eventually they would wear a hole in the timing cover and leak oil. By that time it was overhaul time. Silly things ran forever like that.
 
RustyRatRod said:
Well, you made a decision at least. In my mind how long will it be before that 5/16 is 1/2 or more? Probably not long. Good luck!
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Double roller chain. Being a Chrysler authorised reman it is likely not a top name timing set, but I do not think another 100k miles will wear that timing set much more. My concern would be the cam and lifters being used with modern oils that do not protect the cam and lifters from premature wear.
 
junkyardhero said:
roll dice and let it ride or throw $100 at it as cheap insurance.

are you a gambling man? is it a performance oriented application?

if this is just bread and butter 2bbl or a no juice 4bbl cruiser i'd button that up and ship it. that $100 is better spent on dancing girls and opium.
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Factory authorized reman explains that ?.
Pretty much stock factory.
 
Dale Davies said:
Factory authorized reman explains that ?.
Pretty much stock factory.
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ol DD late to the party as usual.

anyway, if you go back and look he didn't say what his intention was with the motor-- as in any planned upgrades.

anyway, i know you'll have some well thought out retort which i'll promptly ignore. so carry on and enjoy what's left of the saturday.
 
junkyardhero said:
ol DD late to the party as usual.

anyway, if you go back and look he didn't say what his intention was with the motor-- as in any planned upgrades.

anyway, i know you'll have some well thought out retort which i'll promptly ignore. so carry on and enjoy what's left of the saturday.
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Late to the party; I get "this weeks popular chats" on my phone. So I know nothing until I receive it.
 
Run what you have new stuff isn't as good as the old stuff. It's a stock driver. You're worrying too much about it
 
I'm not "worrying" about it.

The timing cover has been cleaned up, the pitted backside surface around the coolant passages have been filled with JB weld and sanded smooth, paper felpro gaskets have been dressed with Permatex aviation goo (I would have used high tack but the store didn't have it). Also replaced the cover crank seal (it came with the felpro set). The cover and new water pump are on as of today, now I need to drive all the way across town to buy another can of red paint and paint everything back the way it was a week ago (but I need other paint also so that's ok, just a pain to mask everything when I had already painted it and looking good).

What I was looking for in this thread was along the lines of

"yes I put in a new chain set just last (week, month, year) and it had a little slack in it almost what you show in your photo, it's a crap shoot with the sets available today how much better any one of them will be compared to what you have now"

or

"yes when you put on a new chain set it should be tight as a drum and it won't matter if you buy Rockauto's $25 set or the $100 set I can tell you it will be tighter than what you show in your photo and your engine will run much smoother at idle".
 
you came to FABO for a simple, straight forward answer?

hahahahah! you fool! you buffoon! everybody knows you use bing for that!

we only peddle in nonsense and what-if's around here!
 
junkyardhero said:
you came to FABO for a simple, straight forward answer?

hahahahah! you fool! you buffoon! everybody knows you use bing for that!

we only peddle in nonsense and what-if's around here!
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Dang skippy.
 
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