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-0.015" Big Block Timing Chain

General engine tech -- Drag Racing to Circle Track

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Kevin Johnson
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Re: -0.015" Big Block Timing Chain

Post by Kevin Johnson » Sun Jan 08, 2017 10:35 am

MadBill wrote: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.
#-o Yes, thank goodness you found out! Three links in succession of differing length installed in a timing chain??? Spintron data?

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Re: -0.015" Big Block Timing Chain

Post by MadBill » Sun Jan 08, 2017 11:34 am

Neat little parts! Did it/they work without modifying the cover? I built this one years ago, but I'd have to hack and weld a 'power bulge' into my shiny new aluminum cover to clear it.. :( Combined with the greater expansion of the aluminum block, I think the dash 10 chain should do the job.
BTW, the deflection in my new stock chain is 0.53", corresponding to ~ 0.011" tighter c-c by Rollmaster's chart. (They also list cam and crank snout diameters a few thous different than my measurements.)
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Re: -0.015" Big Block Timing Chain

Post by MadBill » Sun Jan 08, 2017 11:42 am

Kevin Johnson wrote:
MadBill wrote: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.
#-o Yes, thank goodness you found out! Three links in succession of differing length installed in a timing chain??? Spintron data?
Err...I think the copper links are just a color code for a chain assembled with selected high end of tolerance roller diameters Kevin, e.g. three links times five thous short each equals a-15 chain, not one with three short links. #-o
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Re: -0.015" Big Block Timing Chain

Post by Kevin Johnson » Sun Jan 08, 2017 12:31 pm

MadBill wrote: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.
Kevin Johnson wrote: #-o Yes, thank goodness you found out! Three links in succession of differing length installed in a timing chain??? Spintron data?
MadBill wrote:Err...I think the copper links are just a color code for a chain assembled with selected high end of tolerance roller diameters Kevin, e.g. three links times five thous short each equals a-15 chain, not one with three short links. #-o
Wow, I hope you check that out carefully. Daubs of paint would be another common way to do that. Plating shorter links would be an expensive method to help ensure that they are not mistaken for longer length links when things get mixed together somehow.

At one time Porsche did not use serial numbers on the 928 rod beams and caps. Then suddenly they started doing it with numbers ranging from 000 to 999. Then a customer sent me a picture of an original misaligned cap from his engine with matching serial numbers which indicates that somehow, by chance, the rod and beam from two separately produced parts separated by hundreds of pieces in production became mixed up at the factory.

My old friend, Jean-Claude, described being in a Renault plant and Porsche plant in the 1950s. Workers in the Renault plant could be seen encouraging parts to fit with hammers (ala the comments from the Vincent engineer text you read near the arrival of your son). In the Porsche plant when something did not fit the worker stopped and called out the part and it was checked to see if it conformed to the design specs. Jean-Claude raced both in the Mille-Miglia and LeMans and was later an engineer for Matra.

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Re: -0.015" Big Block Timing Chain

Post by tenxal » Sun Jan 08, 2017 1:21 pm

MadBill wrote: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.
Bill, yes...chain was purchased with the past year. I know that .015 short Cloyes chains for the BBC (9-134-15) have been dc'd by Cloyes. Supposedly, SA Gear will provide chains up to .025 short. Their performance chains are Rolon style...good stuff.

Honestly, I'd opt a Cloyes 9-134-10 and rock on. 8)

Though this could be the shizzle for 'ya..........

http://www.competitionproducts.com/Cam- ... HJ_N32rGzk

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Re: -0.015" Big Block Timing Chain

Post by MadBill » Sun Jan 08, 2017 2:01 pm

Yes, I'm going to add a dash 10 chain to my next order. Together with my 'high expansion block' that should do it.

Re you link: interesting concept! Apparently the right side tensioner (on the 'tight' side of the chain, flying in the face of normal practice) is supposed to stay fully deployed at low RPM , resulting in an advanced cam index, then progressively retract at higher RPM, causing the cam to retard. At the least I'd think the tension would need to be fine-tuned to the cam type and contour, spring force, etc. In reality I can't see how it could possibly work... #-o
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Re: -0.015" Big Block Timing Chain

Post by Kevin Johnson » Sun Jan 08, 2017 2:08 pm

Might be that the image is reversed. Hopefully. I know when I first made scrapers for the Honda B and D series I did not realize they used counter-clockwise rotation.

Another issue with the tensioner on the loaded side is that it increases chordal action. You can see a concern for that with the LS chain guide. If you want to engineer a tensioner based on that, try outward pressure on the normally slack side as that will reduce chordal action. Porsche used that idea in the chain tensioners for the dual cam chain in the later 928 heads.

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Re: -0.015" Big Block Timing Chain

Post by Newold1 » Sun Jan 08, 2017 2:50 pm

Wow, I did not know that CV still offered a kit like that. I know Comp Cams used to have a kit like that but they quit making and offering that about 10 years ago.

Bill, those Feuling tensioners I used obviously required me to drill and tap the block for them and I also used a mill on the block to make a nice flat perch for mounting as the castings on the iron block are not perfectly flat or even. They did fit under a stock 1 piece cover with no interference problem. I did run them on the loaded slack side of the chain. Worked great and I could realize some difference when degreeing the cam.
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Re: -0.015" Big Block Timing Chain

Post by cstraub » Sun Jan 08, 2017 3:11 pm

Rollmaster only has the .005 and .010" oversized sets. They use to make stuff from .002 to .020" but haven't in 10 or so years.
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Re: -0.015" Big Block Timing Chain

Post by jake197000 » Sun Jan 08, 2017 6:33 pm

i could see porsche doing that but they charge for it.i dont actually know but i would think if u g0t a chain set that was correctly designed to b shorter it would cost a hell of a lot more .

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Re: -0.015" Big Block Timing Chain

Post by Schurkey » Sun Jan 08, 2017 10:12 pm

jake197000 wrote:i could see porsche doing that but they charge for it.i dont actually know but i would think if u g0t a chain set that was correctly designed to b shorter it would cost a hell of a lot more .
...and it does.

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Re: -0.015" Big Block Timing Chain

Post by MadBill » Sun Jan 08, 2017 10:18 pm

Err..no. Per: http://www.jegs.com/i/Cloyes/220/9-134/10002/-1 and: http://www.jegs.com/i/Cloyes/220/9-134-10/10002/-1 , the ten thous reduced chain is the same price..
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Re: -0.015" Big Block Timing Chain

Post by Schurkey » Sun Jan 08, 2017 10:29 pm

https://www.summitracing.com/parts/clo-9-3670x3 = standard sizing, $133.

https://www.summitracing.com/parts/clo-9-3670x3-5 = .005 shorter, $152.

I'm surprised that the price difference isn't larger--but then, that chain and gears set used to be $202 at Summit a year ago.

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Re: -0.015" Big Block Timing Chain

Post by MadBill » Sun Jan 08, 2017 11:50 pm

Bizarre. The standard, -5 & -10 chains from Jeg's are all $70. The same p.n.s from Summit are respectively $67, $74 & $65, yet the sets from both, identical but for the chain, are all ~$20 more for the minus sizes.. #-o

OK, Got some great info guys. Signing off the thread now...
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Re: -0.015" Big Block Timing Chain

Post by MadBill » Thu Nov 28, 2019 12:59 am

Post Script:
Received and installed the 'dash ten' Cloyes chain (identified, as specified, by two copper-colored links) and it fits much tighter on the same sprockets as the new standard chain I removed; just enough slack to compensate for the calculated ~ 0.004" C-C greater expansion of the aluminum block.
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