The 383 is torn apart: Pics
As much as I am against the cast aftermarket cranks, between improper assembly and not running the right flywheel its not surprising it broke. What IS surprising is that it lasted that long before breaking. We don't know what else was done to it besides the- it could have also been dropped like stated, or not drilled and balanced properly.
When kept within the modest 500hp flywheel rating and properly assembled with the right flywheel it would probably have lasted forever.
I think one reason we see it more often with Eagle cast cranks is because there are MANY more of them floating around and being used in all sorts of builds that they shouldn't be...and assembled by people who shouldn't be assembling engines.
ANY cast crank is going to break to bits when trying to hold any kind of power...but that being said, the Eagle does not usually have the same quality control as Scat and may need more machining to get it perfect.
When kept within the modest 500hp flywheel rating and properly assembled with the right flywheel it would probably have lasted forever.
I think one reason we see it more often with Eagle cast cranks is because there are MANY more of them floating around and being used in all sorts of builds that they shouldn't be...and assembled by people who shouldn't be assembling engines.
ANY cast crank is going to break to bits when trying to hold any kind of power...but that being said, the Eagle does not usually have the same quality control as Scat and may need more machining to get it perfect.
This is a known problem with the "Eagle Cast cranks" and OP I know you had no choice in this as the engine was in the car when you brought it but I will never understand people who try to "save a few bucks" by buying this cast junk and expecting it to live! I would rather spend the extra $300 - $400 on the frontend and get an all 4340 forged rotating assembly and not have to worry about **** like this.
I can credit my cast crank to my father not doing what I asked him to do even though I was paying for it and I was over 30 at the time lol. He decided I didn't really need it and told the builder this and thats how I got stuck with a cast crank with -16cc pistons even though I wanted to be high 11's on the compression N/A. How bad is it when you can't even trust your family to get it done the way you ask lol.
That is not a family issue, that is an "old school" issue.
The aftermarket cast cranks cost barely any more than turning a stock crank which is I think why some of them sell BUT that should also tell people a LOT about the piece they are getting.
The aftermarket cast cranks cost barely any more than turning a stock crank which is I think why some of them sell BUT that should also tell people a LOT about the piece they are getting.
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TECH Regular
Joined: Jun 2009
Posts: 448
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From: new york
I guess up be the devils advocate here , I had a 383 with eagle internals yes a cast crank . Got it as a prebalanced assembly from eagle . My machinist went and rebalanced it, when I asked him why he said that is why they brake cause of the harmonics and that there balancing is way off . Needless to say I beat the ***** off of that motor and sprayed it all the time . Could I of gotten lucky and got a good one ? Sure I could of but I know of a few others Ford /Chevy/dodge etc that all ran a eagle cast crank that was rebalanced with no problems at all . A lot has to do with who put it together and as said there was picture on the rods it obv wasn't done right .
the eagle cast crank is a weak piece compared to the stock piece but still in the OP's case id say there was probably an assembly issue.......the fact that there was locktite on the rod bolts is a huge issue.......its amazing to me the things these "professional shops" will do...seeing stuff like this makes me want to go full time into mine but oh well.......regardless.......ask the builder for the balance sheet from the motor......he should have a record of all the bob weights as well as piston/rod/ring/pin/oil compensation.......id be curious to see it......also id check your rod/main/piston to wall clearances as well......chances are there are other issues if they were dumb enough to loctite rod bolts.....
TECH Enthusiast
Joined: Aug 2010
Posts: 543
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From: New Hampshire
Wait a second.... OP, you were driving around with a BROKEN crank? As in when you took the motor apart you wern't expecting to find it broken?
The way you worded it in the first post makes me wonder now lol
The way you worded it in the first post makes me wonder now lol
1. Cast does not equal bad. Cheap cast equals bad (and that would include just about ANY aftermarket cast crank, not just Eagle). There's a reason why the aftermarket sells cast cranks - so they can sell a crank to somebody who's too misinformed to stay with an OEM cast crank or too cheap to upgrade to a forged crank. Period.
One of the best engine builders in the country, Tony Bischoff of BES Racing Engines, 5 miles from me, also builds basic 500 hp bracket small blocks for local customers and most of them bring them back to him after a few seasons for refresh. He told me that back in the early days when he would use an aftermarket cast crank per customer request, many of those came back with cracked cranks, but he NEVER had a GM cast crank come back cracked in those motors.
2. Don't kid yourself that a perfect balance job is going to do much to help a junk crank live. If you understand secondary, tertiary, quarternary, blah blah blah imbalances in a reciproctating engine, you realize that you can only overcome the primary and part of the secondary imbalances with traditional 90-degree V8 balance methods. Plus, those imbalances will wreck the bearings before they'll hurt the crank. It's the torsional dynamics that are hardest on cranks; balancing does NOTHING for that. Only the damper up front and the internal damping of the crank material itself keeps those from resonating out of control. Cast can live if there aren't flaws in the critcal areas. Forged is better for 3 reasons: the forging process reduces the chance for those flaws, the forged material has better internal damping characteristics, and it has a higher yield strength.
One of the best engine builders in the country, Tony Bischoff of BES Racing Engines, 5 miles from me, also builds basic 500 hp bracket small blocks for local customers and most of them bring them back to him after a few seasons for refresh. He told me that back in the early days when he would use an aftermarket cast crank per customer request, many of those came back with cracked cranks, but he NEVER had a GM cast crank come back cracked in those motors.
2. Don't kid yourself that a perfect balance job is going to do much to help a junk crank live. If you understand secondary, tertiary, quarternary, blah blah blah imbalances in a reciproctating engine, you realize that you can only overcome the primary and part of the secondary imbalances with traditional 90-degree V8 balance methods. Plus, those imbalances will wreck the bearings before they'll hurt the crank. It's the torsional dynamics that are hardest on cranks; balancing does NOTHING for that. Only the damper up front and the internal damping of the crank material itself keeps those from resonating out of control. Cast can live if there aren't flaws in the critcal areas. Forged is better for 3 reasons: the forging process reduces the chance for those flaws, the forged material has better internal damping characteristics, and it has a higher yield strength.
Agreed but Id never use a CAST eagle crank no matter what with my goals. I am using a Forged Eagle crank that has been fully gone over and rebalanced in my 383.
What I am saying is people want to blame only bad balance, if that were the cause we would see badly balanced stock crank motors fail as well. Far as what fails and what sells that is a flawed argument, people are stupid and like to defend their mistakes.
Staging Lane
Joined: Jun 2007
Posts: 75
Likes: 0
From: detroit
eagle cast = junk same problem eagle cast cranks are junk. check your crank damper and saddle bore. mine was wacked out loose main caps converted to 4 bolt main. i was also able to drive home . just started as a misfire like a loose wire and a clunk as i pulled in my driveway. never made it to the track. was just cruzin down the freeway. ran gr8 then a clunk. never going to buy eagle again to .just like fireworks made in china and go out with a bang. not to l8 for small claims court. if you want to swap pics pm me. Matt
TECH Fanatic
Joined: Feb 2006
Posts: 1,025
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From: CT/NJ
Good stuff. I have seen 6.5 diesels wobble in under their own power with 3 rods hanging out of the pan and the crank in 3 separate pieces (with the customer complaint as alternator not charging) so, you haven't set any records yet. 
