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Has anyone used a scat rotating assembly for a stroker build?

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Has anyone used a scat rotating assembly for a stroker build?

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Old 12-07-2018, 12:34 PM
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Default Has anyone used a scat rotating assembly for a stroker build?

I am on the fence of jumping from 454 mag stock internals on full rebuilds or making the jump to a scat stroker rotating assembly. Scat sells them both balanced and unbalanced, I would prefer to use the machine shop as little as possible due to time and it seems like every time I take even simple things in to the machine shop I end up with a huge bill. I am looking at the kits from summit that have the scat 9000 crank which is the only cast crank I would trust, scat forged I beam rods w/ARP bolts, Icon forged dome pistons that will bump me to 9.6-1 on 934 heads, rings and bearings are all included for 1306 unbalanced or 1483 balanced w/freight. Some people say donít trust the balance, some say they have had them checked and were spot on, some say they were messed up. The only thing I see that I am loosing from going 454 to stroker is the forged crank, these engines are going in a 38 stinger that is likely never going to be a speed demon of any sort due to size and weight, hoping to get 500-550hp when done so I donít see the scat cast crank being an issue. I am mainly worried about the balance on these kits, the parts all seem to have a good reputation based on my research and discussions with marine engine builders. Has anyone else used these kits?
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Old 12-07-2018, 02:11 PM
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First Scat has come a long way from the old days and has passed eagle and a few others when it comes to cranks. Most of their other stuff imho has always been good (just like Howards Cams). As for balancing, take it to a shop. With the internet you are not trapped with your local guy. They (Summit) can balance what they send you but you will still need your Harmonic Balancer and Flywheel done to do it right. Here is my build sheet for a Mark IV stroker. Current Build Sheet SuperNova19.com
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Old 12-07-2018, 02:24 PM
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I have seen several of your posts on that build searching through the forums. I don't think summit balances these, I think scat does. Part of me thinks who better to balance it than the people putting these kits together. To my understanding these kits are internally balanced so that you use a neutral balancer and flywheel. I was originally looking at the skip white kits that had the balancer and flywheel but their kits did not offer a piston that would get me into the right compression ratio. The last time i checked the back log at my machine shop, they were a good month or so out with back log
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Old 12-08-2018, 01:34 AM
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I hear ya but I still would rather for the balancer to have everything at once. Maybe the rods are heavy and all they would have to do is drill the flywheel instead of balancing all the rods to the new weight. Maybe your flywheel is not perfect? Who knows but I would not trust OEM parts to be perfect. As for the "balanced kit", all their parts in this range are "balanced" like all the pistons will be within a gram or so in a set (I forget exactly what the tolerance is). Each rod's weight will be within so many grams and etc etc. A balanced kit may be just balanced parts picked off a shelf and not balanced to each other as a rotating assembly. Also I stroked a 427 tall block that is a internally balanced when I started. They drilled both the balancer and the flywheel to clean it up.
Last, are you sure you 454 is internally balanced? That don't sound right to me.
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Old 12-08-2018, 07:09 AM
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I would call Scat and get a rundown as to what process their balanced kit goes thru....

Balance Rotating Assemblies - Chevy High Performance Magazine

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Old 12-08-2018, 07:46 PM
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Just my opinion however I would never trust a balanced rotating assemble and honestly Id purchase a neutrally balanced 8 counterweight 4340 assembly and have it internally balanced. Balancing is huge to long jevity to your engine. I know some may have had great success with those balanced kits. I might use in a budget build street car engine but not for a marine build that's being thrashed on running higher rpm's for long distant runs. Even with that said I would still send out to reputable machine/speed shop to have checked out.

The end end result is if you step up to a better rotating assembly you will have a solid foundation for future power. The last 496's I built come in at 623 hp @ 6k.
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Old 12-09-2018, 11:22 AM
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I emailed scat and got the run down. They balance them whithin 5-7 grams which in my mind is not good enough considering the cost vs doing it local so I guess I am buying the unbalanced kit and going local. thanks everyone for the help!
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Old 12-09-2018, 11:37 AM
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I used two 4.25 on 540 builds a few year ago, Smith power balanced the rotating assemblies, Bob Smith said dont bring me another one.....LOL.....maybe they have improved ??
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Old 12-09-2018, 01:14 PM
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On a side note, please make sure you put your rod bearings in right when it comes to after market cranks. Make sure you don't need "narrowed" bearings.
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Old 12-09-2018, 03:59 PM
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I would use a Crower instead of a Scat. And for surely never use a Eagle branded in any marine engine. Just saying
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