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-0.015" Big Block Timing Chain

General engine tech -- Drag Racing to Circle Track

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MadBill
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Re: -0.015" Big Block Timing Chain

Post by MadBill » Sat Jan 07, 2017 9:36 pm

cpmotors wrote:
MadBill wrote:Incorrect. The Cloyes tech line is (479) 646 -1662, ex. 228. Call them yourselves to verify if you like but their catalog lists 9-134 as the standard length BB chain; to be followed by a -5 or -10 for 0.005" or 0.010" closer c-c respectively. When I talked to their tech yesterday he said: "Sorry, we don't make the fifteen thous. short chain anymore."
Not a fan of Cloyes, but may I submit some more food for thought here Bill.
I just counted 33 links in the chains I use. To change the Overall length of that chain by -.015"=.00045" per link. That's 4.5 TEN THOUSANDS of an inch change in center to center distance per link. But we are talking Centerline Distance of the CAM/Crankshaft. Sprockets are measured at the root of the tooth vs pitch diameter like gears. I submit that Cloyes is using the usual tactics about chains when in fact they change the root diameter of the gears themselves vs attempting to making chains that alter the link center distance in Ten Thousands of an inch to loose .015" in Center to Center distance across 5.152".
Sounds logical, but per http://www.jegs.com/i/Cloyes/220/9-134-5/10002/-1 and http://www.jegs.com/i/Cloyes/220/9-134-10/10002/-1 Cloyes offers short chains for reduced c-c apps, not larger sprockets.
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Re: -0.015" Big Block Timing Chain

Post by pamotorman » Sat Jan 07, 2017 9:44 pm

all aluminum BBC the valve lash changes .010 room temp to operating temp. I always allowed .005 tighter squish on aluminum blocks.

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Re: -0.015" Big Block Timing Chain

Post by Kevin Johnson » Sat Jan 07, 2017 9:49 pm

You might ask if the -05, -10 and -15 refer to chain stock that is subjected to decreasing amounts of pre-stress. If so, it might be possible to obtain a length of chain that has not been pre-stretched and construct your own.*

*Stretching in use typically refers to wear, which is different albeit still resulting in a length increase.

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Re: -0.015" Big Block Timing Chain

Post by jake197000 » Sat Jan 07, 2017 9:54 pm

i agree.if u just make the chain shorter and use the same sprocket it will just wear in and go slack and create more trash in the oil

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Re: -0.015" Big Block Timing Chain

Post by MadBill » Sat Jan 07, 2017 10:02 pm

pamotorman wrote:all aluminum BBC the valve lash changes .010 room temp to operating temp. I always allowed .005 tighter squish on aluminum blocks.
Yes, my old and (formerly) 0.008"+ loose pistons 495" has less than 0.035" cold squish and not trace of piston/head contact. Aluminum thermal expansion is 12.3 ppm and cast iron is 6.0, so by the numbers, a 9.8" aluminum block heated from 70° F. to 180° would expand by (12.3-6) x (180-70) x 9.8/1000000 = 0.0068" more than an iron one. Similarly, the crank/cam c-c would grow by 0.0036" more.
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Re: -0.015" Big Block Timing Chain

Post by MadBill » Sat Jan 07, 2017 10:09 pm

jake197000 wrote:i agree.if u just make the chain shorter and use the same sprocket it will just wear in and go slack and create more trash in the oil
I did say 'shorter', but that's just a verbal shortcut; I believe in actuality the individual rollers are sorted and selected to the high side of the diameter tolerance. Sort of like 'quiet' and 'noisy' gear drives: Both part sets come off the same machines at the same time and are then boxed by tolerances. Pretty neat when you can package and sell what should be rejects for full list...
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Re: -0.015" Big Block Timing Chain

Post by MadBill » Sat Jan 07, 2017 10:20 pm

Kevin Johnson wrote:You might ask if the -05, -10 and -15 refer to chain stock that is subjected to decreasing amounts of pre-stress. If so, it might be possible to obtain a length of chain that has not been pre-stretched and construct your own.*

*Stretching in use typically refers to wear, which is different albeit still resulting in a length increase.
Speaking of stretch, Rollmaster has a handy chart for determining the required compensation (larger sprockets in their case) for line bored engines. It converts the slack measurement to the required correction. Of course you'd need a known 'like-new' chain for an accurate measurement, so maybe not so handy after all... :-k
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Re: -0.015" Big Block Timing Chain

Post by Tuner » Sat Jan 07, 2017 10:26 pm

MadBill wrote:
jake197000 wrote:i agree.if u just make the chain shorter and use the same sprocket it will just wear in and go slack and create more trash in the oil
I did say 'shorter', but that's just a verbal shortcut; I believe in actuality the individual rollers are sorted and selected to the high side of the diameter tolerance. Sort of like 'quiet' and 'noisy' gear drives: Both part sets come off the same machines at the same time and are then boxed by tolerances. Pretty neat when you can package and sell what should be rejects for full list...
You said "rollers" but I think you meant "links" #-o

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Re: -0.015" Big Block Timing Chain

Post by MadBill » Sat Jan 07, 2017 10:35 pm

No, I believe it is the rollers. If each one is a tenth or so larger, they all ride a little higher in the sprocket tooth throats, thus increasing the radius the chain must follow and taking up the slack.
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Re: -0.015" Big Block Timing Chain

Post by cpmotors » Sat Jan 07, 2017 11:44 pm

I'd be curious to know what the truth actually is. Jegs or Summit doesn't QC check anything, they just list a product to sell. I don't see Cloyes hand selecting rollers by OD to match anything, too time consuming in this day and age of profit driven products. I can see them adjusting sets by checking the root diameter of the gear sets to make "matched" sets, as described on their website. Because the process of cutting sprockets is based off of touching the cutter off the OD of the blank, and moving in a set depth. So tolerance stack of sprocket blank OD's, depth adjustments, hob wear, and final size can vary .005" easy in a production setup. The machines, after all, are run by employees.
My bet is the chains are replacement chains for those sets, same as the standard sets, marked with -5/-10 to add a few dollars. Not actually shorter chains, just replacements that are compatible with those gear sets, and the tech guy has no clue how they are actually made. Thats why the jig to check the CL distance on each set by swapping different sprocket diameters in place to make that adjustment. Order a standard set and -.010 and measure the sprocket root diameters, or measure your gears over pins and ask them what chain will work? :D
The main reason I believe this is the case, besides working in a gear shop for 9 years, is I had an LA Chrysler that I ended up with 2 chains sets, the second being a Cloyes (yes it hurt to buy one) and the upper sprocket was +.005" over the billet set, and the crank gear was +.010" over the billet set,measured at the root diameter, and the chain went from being slack enough to about come off to being perfect .250" slack at midpoint.

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Re: -0.015" Big Block Timing Chain

Post by MadBill » Sat Jan 07, 2017 11:59 pm

I dunno. How many hundreds (thousands?) of guys have had blocks line bored and so ordered a Cloyes dash 5 or dash 10 chain to compensate? If the "-10" chain fits exactly like the standard one, how is that going to help Cloyes (or Jegs, etc.) in the long term?
We can either wait a week or so until I order one in or if anyone has tried one, perhaps he will weigh in.. :?
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Re: -0.015" Big Block Timing Chain

Post by Kevin Johnson » Sun Jan 08, 2017 3:22 am

:D
That is amazing process control that off-spec parts will vary in resultant center to center increments of .005" !!

Gosh, if I had a pneumatic matching fixture I could add a skosh (technical term) more or less stretch. Presto!

Yes, my employer sold air-floated soap flakes which was the process dust collected around the machines so I am familiar with the no-waste concept (and charge more to boot). :wink:

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Re: -0.015" Big Block Timing Chain

Post by tenxal » Sun Jan 08, 2017 8:11 am

I recently replaced a standard length Cloyes chain with one of their .015 short chains on a line bored small block Chevy using the original gears...worked great.

Each copper colored link plate indicates a .005 shorter chain.

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Re: -0.015" Big Block Timing Chain

Post by MadBill » Sun Jan 08, 2017 8:39 am

Thank you so much for that input of fact vs. speculation tenxal! =D>
Was the chain a recent purchase? As I mentioned, their tech guy said they no longer make the -15 part for the BB.
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Re: -0.015" Big Block Timing Chain

Post by Newold1 » Sun Jan 08, 2017 10:29 am

Hey Bill

This may work for you as I have used these on a couple of BBC bad line bore blocks that I salvaged for a super loose timing chain fitment that the -.010" chain set would not fix. They are inner timing chain tensioners made by Feuling Motorsports(remember that name!) They are small billet aluminum units with a spring loaded nylon guides and I was able to machine and mount them under the timing cover. I don't know if they will work under a billet two piece cover but its worth a look for you. Part #'s 8075-8076 Hope my trick works for you! :)

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