#1  
Old 09-18-2020, 08:00 PM
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Default timing chain stretch

I installed a new timing chain yesterday and it seems a little loose. Is this acceptable? I posted a couple of pics
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  #2  
Old 09-18-2020, 09:00 PM
PontiacJim1959 PontiacJim1959 is offline
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It will have some play, but not a bunch. If the engine has ever had the mains align bored, it can effect the crank centerline and you may need a slightly undersized timing chain.

However, it may also be the chain/gear set itself - some are better quality than others.

One of the engine builders on the forum can give you a few things to consider & check.

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Old 09-18-2020, 09:57 PM
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Hopefully Cliff Riggles will see your post and comment since you're using a Morse chain and those are what he advocates. Cliff deplores the roller chains as "bicycle" chains and not very durable. He knows your type of chain well and can give good advice.

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Old 09-19-2020, 07:49 PM
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Here are a couple of videos showung how to determine too much slack/stretch. Hope this helps.

https://www.youtube.com/watch?v=4_f5ukZVri8

https://www.youtube.com/watch?v=ySfy9oD-qGI

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Old 09-19-2020, 08:37 PM
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I thought I read somewhere if you put a straight edge on chain and measure slack distance, you don’t want more than about 3/8”

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Old 09-20-2020, 06:05 AM
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I always install my Cams with a 2 degree advance key once I have degreed them to compensate for normal timing chain stretch, no less when they are loose from the get go!

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Old 09-20-2020, 06:27 AM
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Most are tighter than a banjo string when first installed. Has the block been aligned bored or honed at some point? How much play does it actually have?

I had the timing cover off my 455 recently and after 10 years it had a little play in the chain but nothing alarming. I had actually planned on replacing it while the cover was off (water leak) but it showed nothing more than some witness marks on the gears and maybe 3/8" of movement on the chain so I buttoned it right back up for another 10 years or so.......Cliff

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  #8  
Old 09-20-2020, 01:48 PM
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Thanks everybody for the replies, I looked on the cloyes website and these types of chains are pre stressed, anyways the new one I installed (napa part #) is loose. With the harmonic balancer installed there was 2 degrees of free movement (this is a new part). Too much for my liking the old one was 5 degrees of movement.
update I have found another new chain in my boxes of car stuff this one is a sealed power unit. I am going to install it looks to be better quality although the gears all have the same part number. Then there is the balancer bolt fitment i'm not to thrilled about.

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Old 09-21-2020, 06:12 AM
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If you not using original hardware in terms of the Balancer bolt, note that I have seen replacement bolts that are not as long as the factory one.

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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs!
And he was not talking about 1/8 or 1/4 mile ETs!

1) 1940s 100% silver 4 cup tea server set.

Two dry rotted 14 x 10 Micky Thompson slicks.

1) un-mailed in gift coupon from a 1972 box of corn flakes.
Two pairs of brown leather flip flops, never seen more then 2 mph.

Education is what your left with once you forget things!
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Old 09-21-2020, 06:47 AM
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If you want a banjo string tight timing chain set-up plan on pulling the front cover off the engine and putting on a new chain a couple of times a year. It's just the nature of the beast and ALL of these chains, whether it be the factory Morse type or the highest end seamless true roller on billet sprockets....they ALL develop some slop once placed in service.

WAY back on 2000 when I built my first 455 for the Ventura I bought all the parts from KRE. They included a Rollmaster Timing set with the 9 keyway option. I had never used one but liked the easy cam movement deal so gave it a try. A few years later I even did some testing with cam ICL position and moved the cam 4 times, then raced the car after each movement plus evaluated it on the street, etc.

Anyhow, the chain already had a decent amount of play in it, but nothing alarming. I see about the same amount with a factory link type chain with the same amount of use so never gave it much thought, just buttoned things up and continued to drive and race the car as often as I could.

A few years later I was racing at a track up North and the car slowed WAY down in both ET and MPH and the engine just didn't sound right. I ended up pulling the engine even though it passed a compression test and the cam lobes all looked in mint condition. I just figured it was getting "tired" and could use some rings and rolling in a new set of rod bearings.

Turns out the only thing really wrong with it was the timing chain. It had stretched out to a point where you could nearly touch it together under the top gear. Now granted I'm not on here to bad mouth the very popular Rollmaster timing set, it served me quite well for many years, but it eventually needed replaced.

With this topic we don't get a lot of accurate feedback because a high percentage of the customer base isn't putting but a few thousand or even hundred miles on these cars per year. So even the low end timing sets will fair pretty well for most users.......FWIW......Cliff

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  #11  
Old 09-21-2020, 07:26 PM
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How do the timing belts hold up?

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