Moparts
Anyone broke an LY or 6 pack rod?
Posted By: GTX MATT
Anyone broke an LY or 6 pack rod? - 01/06/15 05:32 PM
Just for fun - the small block rod thread got me thinking. I have a 400 shortblock with a bent connecting rod, it is bent slightly in the non thrust direction.
I also have a friend with a 67 HP 440 sitting on his garage floor that he grenaded around 74, it has a couple of broken LY rods and a few that actually bent about 90 degrees and did not break. The engine is so screwed up that you can't get it apart. He shifted it around 6500-6800. Obviously he broke it with excessive RPM. And it had heavy TRW 6 pack slugs in it.
What stories do you guys have?
Posted By: CHAPPER
Re: Anyone broke an LY or 6 pack rod? - 01/06/15 05:40 PM
I don't think ANYBODY has ever broken a six-pack rod.
Posted By: MRMOPAR622
Re: Anyone broke an LY or 6 pack rod? - 01/06/15 05:49 PM
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I don't think ANYBODY has ever broken a six-pack rod.
Not the rod but on my 1st and only set of 6 pack heavy A$$ rods a rod bolt broke about the same as breaking a rod @ 6200 RPM just as I was about to shift !And still today wonder what the Hell I was thinking putting a set of Heavy Ass set of rods in a engine! 
Posted By: CHAPPER
Re: Anyone broke an LY or 6 pack rod? - 01/06/15 06:10 PM
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I don't think ANYBODY has ever broken a six-pack rod.
Not the rod but on my 1st and only set of 6 pack heavy A$$ rods a rod bolt broke about the same as breaking a rod @ 6200 RPM just as I was about to shift !And still today wonder what the Hell I was thinking putting a set of Heavy Ass set of rods in a engine!
The 6pk used to be the way to go. Hardly anybody uses them anymore. I had several sets here that I ended up giving to a junker that comes around. See them on Ebay for sale, but nobody bids/buys. Only a diehard restorer would want them I guess. 
Posted By: Quicktree
Re: Anyone broke an LY or 6 pack rod? - 01/06/15 06:13 PM
i don't think very many racers run the heavy things, why would they?
Posted By: BradH
Re: Anyone broke an LY or 6 pack rod? - 01/06/15 06:31 PM
I used to keep a bag on my desk at work with a bunch of LY rod pieces from when I grenaded it at the 1000-ft. mark years ago. You could make a jig-saw puzzle with them.
Like another poster mentioned, the break probably started with a bolt, but by the time it was all said and done, it was a whole bunch of pieces, plus a broken camshaft, plus an effed-up block & crank, etc.
Posted By: JERICOGTX
Re: Anyone broke an LY or 6 pack rod? - 01/06/15 07:31 PM
Paging Mopar Billy...
Posted By: JAKE68
Re: Anyone broke an LY or 6 pack rod? - 01/06/15 07:54 PM
LOTS!!!!!!!!!!!!
Posted By: Twostick
Re: Anyone broke an LY or 6 pack rod? - 01/06/15 08:51 PM
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Paging Mopar Billy...
It ain't blew up until it's Mopar Billy blew up.
Kevin
Posted By: dannysbee
Re: Anyone broke an LY or 6 pack rod? - 01/06/15 11:17 PM
Yes I have. Ly. Will I again? No after market rods are too cheep and blue printed short blocks are too expensive.
Posted By: JACK1440
Re: Anyone broke an LY or 6 pack rod? - 01/06/15 11:17 PM
This one is my favorite. Broke at the stripe. Couldn't even get the cam out of the block. I loved that motor....
Posted By: Chris2581
Re: Anyone broke an LY or 6 pack rod? - 01/06/15 11:39 PM
Never broke a LY rod,but had one that a bolt snapped in...engine had 27 runs on it. New engine has a brand new set of LY's with ARP bolts and 6 pak slugs,but it will never go over 6000 rpm.
Posted By: pittsburghracer
Re: Anyone broke an LY or 6 pack rod? - 01/07/15 12:25 AM
I put a lot of of high 9, low 10 second passes on stock 440 rods with upgraded rods bolts,and polished and shot blasted beams. Some broke, some didn't. Would I do it again with whats available now? HECK NO. Another thing to remember was that back then most of us were running stock cranks and HEAVY TRW or Sealed Power pistons.
Posted By: camastomcat
Re: Anyone broke an LY or 6 pack rod? - 01/07/15 01:08 AM
I broke some, but I couldn't say it was the rod's fault.
Posted By: FastmOp
Re: Anyone broke an LY or 6 pack rod? - 01/07/15 01:13 AM
Yep. Broke it in the water. Kept running till I got it on the trailer.
Posted By: MRMOPAR622
Re: Anyone broke an LY or 6 pack rod? - 01/07/15 02:08 AM
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I put a lot of of high 9, low 10 second passes on stock 440 rods with upgraded rods bolts,and polished and shot blasted beams. Some broke, some didn't. Would I do it again with whats available now? HECK NO. Another thing to remember was that back then most of us were running stock cranks and HEAVY TRW or Sealed Power pistons.
Would you be talking about the L2295 heavy weight pistons? 
I run them with a CD 286-750 roller camshaft.
Posted By: birdtracker
Re: Anyone broke an LY or 6 pack rod? - 01/07/15 02:08 AM
I vaporized one on a 12-1 motor with a 613 Ultradyne and ported 906s. All that was left was a small piece around the crank, and a piece at the top with the pin. The rest was dust. A piece went thru one of the freeze plugs and it started leaking water. Drove it on the trailer. Birdtracker
Posted By: pittsburghracer
Re: Anyone broke an LY or 6 pack rod? - 01/07/15 02:44 AM
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I put a lot of of high 9, low 10 second passes on stock 440 rods with upgraded rods bolts,and polished and shot blasted beams. Some broke, some didn't. Would I do it again with whats available now? HECK NO. Another thing to remember was that back then most of us were running stock cranks and HEAVY TRW or Sealed Power pistons.
Would you be talking about the L2295 heavy weight pistons?
I run them with a CD 286-750 roller camshaft.
Oh ya those same pistons and I still have probably 3 of the old 286 duration 750 lift cams on my shelf. They were GREAT cams back then and made some nice power with the old garage ported 906 heads. LOL. I finally sold off all my old TRW, Sealed Power pistons last Summer.
Posted By: RUNCHARGER
Re: Anyone broke an LY or 6 pack rod? - 01/07/15 04:55 AM
I broke a couple. Used to break the bolts I think but it was sometimes hard to tell what happened first, started cutting 100 grams out of those old forged pistons and that helped a lot. No need to run that junk these days.
Sheldon
Posted By: Sport440
Re: Anyone broke an LY or 6 pack rod? - 01/07/15 05:20 AM
Never broke one!! I bent one once though. It bent almost a 180 degrees at the piston pin end but yet, it still didn't break!. Tough little suckers they were, those LY,s. In most cases IMO, either the rod bolts broke first or the bearings spun causing the rod bolts to snap. Then all else happened afterwards.
Posted By: gdonovan
Re: Anyone broke an LY or 6 pack rod? - 01/07/15 01:06 PM
Quote:
He shifted it around 6500-6800. Obviously he broke it with excessive RPM. And it had heavy TRW 6 pack slugs in it.
What stories do you guys have?
You are making me cringe.
GTX still has "old school" 440 that I built in the mid 90's. Mcandless ported heads with oversize valves, battleship springs with titanium retainers and max wedge rocker gear with a 590 cam.
Forged six pack slugs, LY rods that are shot peened with ARP bolts.
On its best pass (11.2 at 124) it went through the traps at 7200. I remember looking at the tach as the needle was rising wondering if the blow shield would hold if the flywheel let go...
Motor still runs great though I bet the ring seal is not as good as it once was and she marks her spot time to time.
Posted By: an8sec70cuda
Re: Anyone broke an LY or 6 pack rod? - 01/07/15 03:15 PM
Not me personally, but I bought an old Duster drag car once that had the top 1/2 of a 6 pack rod laying in the trunk. The rod had broken, but surprisingly hadn't hurt anything else except for hitting a piston skirt. I never saw the crank or the other 1/2 so I can't say if it was a broken bolt or a turned bearing that caused it.
They swapped in a set of LY rods and kept on going, lol. Had the old 2295 TRW slugs in it.
Friend of mine had a 600 hp 440 w/ a stock crank and six pack rods that ran high 9s in a back half cuda bracket car for a long time. I bought the motor and ran it for a little while, but then tore it down for a rebuild and put some Manley H beams in it.
Posted By: GTX MATT
Re: Anyone broke an LY or 6 pack rod? - 01/07/15 06:53 PM
Quote:
Quote:
He shifted it around 6500-6800. Obviously he broke it with excessive RPM. And it had heavy TRW 6 pack slugs in it.
What stories do you guys have?
You are making me cringe.
GTX still has "old school" 440 that I built in the mid 90's. Mcandless ported heads with oversize valves, battleship springs with titanium retainers and max wedge rocker gear with a 590 cam.
Forged six pack slugs, LY rods that are shot peened with ARP bolts.
On its best pass (11.2 at 124) it went through the traps at 7200. I remember looking at the tach as the needle was rising wondering if the blow shield would hold if the flywheel let go...
Motor still runs great though I bet the ring seal is not as good as it once was and she marks her spot time to time.
I ain't gonna lie to ya Gary 7200 on stock rods would scare me, but lots of people have done it. I built mine to turn 7K with Scat H beams, studded mains, and 525 gram forged pistons and I'm a little scared to bring it up that far.
What are you using for bearings out of curiousity and how do you like that 590 on the street?
If it makes you feel better the same friend bought a 67 GTX brand new and for 2 years spun the stock short block (never opened, so factory clearance on everything) to 7K, that was brand new of course though but the car saw street duty as well, never broke it. 
I'm guessing like many others the one on his garage floor started with a rod bolt.
Posted By: dogdays
Re: Anyone broke an LY or 6 pack rod? - 01/07/15 08:23 PM
A while ago there was an interview in Mopar Action with a guy who had been in the engine room at Chryco. I don't remember the name and don't remember what the factory term was for dyno testing, but it wasn't dyno testing.
He had tested many many engines and said the 440s they'd run for hours and hours and they kept gaining power. After X number of hours the power would have maxed out, that was the number. If they kept testing the same engine it'd soon break. If a rod broke it'd pull off something like an inch below the pin. I believe this was why the 908 rods were designed with the thicker beam.
I don't know why Mopar engineers were so in love with heavy pistons, except that they designed engines that usually had pretty short strokes and the heavy piston isn't so much of a detriment, also the heavy pistons probably were much more durable.
R.
Posted By: GTX MATT
Re: Anyone broke an LY or 6 pack rod? - 01/07/15 08:45 PM
I don't think they were in love with heavy pistons, I think they were in love with tall pistons, for greater stability in the bore. They were heavy as a product of being tall. They were pretty strong for factory cast slugs though.
Unfortunately it also makes aftermarket parts selection harder. Aftermarket rods are all .008 inches short, lots of short pistons, etc.
And also so that we could stroke them easy later.
Posted By: pittsburghracer
Re: Anyone broke an LY or 6 pack rod? - 01/07/15 09:01 PM
Years ago I had a local coal company that would sell me the 440 engines off their old generators for 50 bucks for a complete forged crank engines. Man I miss those days
Posted By: Willie68coronet
Re: Anyone broke an LY or 6 pack rod? - 01/07/15 09:50 PM
Quote:
I ain't gonna lie to ya Gary 7200 on stock rods would scare me, but lots of people have done it. I built mine to turn 7K with Scat H beams, studded mains, and 525 gram forged pistons and I'm a little scared to bring it up that far.
Which 440 pistons do you have that 525? Lightest I've seen advertised are CP at around 625. My late 1990's JE's I have on the shelf are 645. I'm curious of what you have, if that wasn't a typo?
Posted By: gdonovan
Re: Anyone broke an LY or 6 pack rod? - 01/08/15 12:29 AM
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What are you using for bearings out of curiousity and how do you like that 590 on the street?
Pretty sure they were Clevite bearings as that is pretty much all I would use at the time and the 590 cam was pretty fun on the street.
Better roller grinds now though if you have the choice but as far as flat tappet the 590 is nice.
Posted By: dogdays
Re: Anyone broke an LY or 6 pack rod? - 01/08/15 12:58 AM
A 3.75 stroke engine with 7/16" high quality rod bolts and 600 gram pistons should live at 8000 rpm indefinitely.
R.
Posted By: GTX MATT
Re: Anyone broke an LY or 6 pack rod? - 01/08/15 01:53 AM
Quote:
Quote:
I ain't gonna lie to ya Gary 7200 on stock rods would scare me, but lots of people have done it. I built mine to turn 7K with Scat H beams, studded mains, and 525 gram forged pistons and I'm a little scared to bring it up that far.
Which 440 pistons do you have that 525? Lightest I've seen advertised are CP at around 625. My late 1990's JE's I have on the shelf are 645. I'm curious of what you have, if that wasn't a typo?
No typo, Wiseco Pro Tru PT034H3, great price too I paid 500 with rings 
Posted By: cudatom
Re: Anyone broke an LY or 6 pack rod? - 01/08/15 02:47 AM
Quote:
Quote:
He shifted it around 6500-6800. Obviously he broke it with excessive RPM. And it had heavy TRW 6 pack slugs in it.
What stories do you guys have?
You are making me cringe.
GTX still has "old school" 440 that I built in the mid 90's. Mcandless ported heads with oversize valves, battleship springs with titanium retainers and max wedge rocker gear with a 590 cam.
Forged six pack slugs, LY rods that are shot peened with ARP bolts.
On its best pass (11.2 at 124) it went through the traps at 7200. I remember looking at the tach as the needle was rising wondering if the blow shield would hold if the flywheel let go...
Motor still runs great though I bet the ring seal is not as good as it once was and she marks her spot time to time.
Sounds like my old combo except I ran the heavy TRW2295 pistons and 6 pk rods. Crossed the stripe at 6800 and ran 10.82 in my Cuda. The most consistent motor I ever had. Ran for 14 yrs until bang at the stripe. Was not pretty. Broke the block, cam, one 6 pk rod in 4 pieces and 3 more twisted like pretzels. 
Posted By: RSNOMO
Re: Anyone broke an LY or 6 pack rod? - 01/08/15 03:52 AM
Got 20 years going on LY's with ARP bolts, under forged, six-pak TRW's...
Posted By: 6PAK70CUDA
Re: Anyone broke an LY or 6 pack rod? - 01/08/15 04:10 AM
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Got 20 years going on LY's with ARP bolts, under forged, six-pak TRW's...
I bought a used bracket 440 off a buddy and heavy (2350P I think) pistons, LY rods, solid lifter cam and usually buzzed it 6500-7000 rpm and it did go when I bent a pushrod and lifter popped and then low oil press and you know the rest...
I remember going to a Herb McCandless seminar back at the Nats in the 80's and asked him what could be done to improve RB bottom ends and he replied "they are strong enough; it's usually an oiling problem. If you put beefier parts in you just do a better job of sawing the motor in half when it lets go due to the oiling problem"
Now that was well before aftermarket heads and power adders that have us pushing them to power levels previously unattainable but words to consider for those of us running "old school" combos.
Posted By: therocks
Re: Anyone broke an LY or 6 pack rod? - 01/08/15 05:43 PM
I have a LY in the garage that is bent pretty good.My machinst asked if the motor ran.I said yes it did and was spun over 6K many times with the bent rod.Its not a slight bend either.Rocky
Posted By: MRMOPAR
Re: Anyone broke an LY or 6 pack rod? - 01/08/15 11:00 PM
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Paging Mopar Billy...
I'd still like to see MoparBilly chime in here. He ran LY rods with some very BIG loads of NOS... Somewhere back in the long ago archives, he told the story about that! Made very interesting reading!
Posted By: 451Mopar
Re: Anyone broke an LY or 6 pack rod? - 01/09/15 02:07 AM
I'm lucky, never broke one. The old 451 "B" engine used the cut down 440 crank and LY rods with ARP bolts, and light weight Ross pistons. I figured the rods were the weak point of the short block, but they held up very well in that motor, and a broken intake valve did in the engine after 10+ years of street and strip driving/racing.
When I first built the engine in the 1990's, several friends asked me what I was going to do when a broke one of the LY rods? I would tell them "I'll build a bigger engine."