6.75" Harmonic Balancer (ext) users step inside
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From: Overland Park Kansas
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6.75" Harmonic Balancer (ext) users step inside
What balancer have you used with your ext/ext cranks? I'm hearing the Performance Products 80001 (PowerForce) might not be a good option. The only other one I can find is a 90001 by the same company.
And, to confirm, I can't use an 8" balancer, right?
And, to confirm, I can't use an 8" balancer, right?
Le Mans Master
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From: Australia
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I used one on my Scat EXT balance 400 crank, no issues
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From: Overland Park Kansas
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I've been running around trying to figure out the best ext front blancer to use with my Scat9000 ext crank. Even though the first Scat rep (that I talked to) told me they're ext/ext, it turns out the 5.7" rod crank is ext rear/int front!!! (I just called to see if they had a balancer to recommend. The second guy corrected the first guy's info.)
Kinda makes the options a little different, don't it?
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I've been running around trying to figure out the best ext front blancer to use with my Scat9000 ext crank. Even though the first Scat rep (that I talked to) told me they're ext/ext, it turns out the 5.7" rod crank is ext rear/int front!!! (I just called to see if they had a balancer to recommend. The second guy corrected the first guy's info.)
Kinda makes the options a little different, don't it?
That is odd. The last 10 I have done have been external, external. I wonder if they changed them recently, or the new guy answered the phone the second time.
Thread Starter
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From: Overland Park Kansas
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Pete,,,are you talking 5.7" or 6" rod cranks? Cause it sounded like 6" cranks are ext/ext.
Jake,,,it's and 89. Factory config is "hybrid". But aftermarket can be anything.
Jake,,,it's and 89. Factory config is "hybrid". But aftermarket can be anything.
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Now that I think about it, all cast Scat cranks I have purchased for 2 pc seal blocks with 5.7 rods were external front and rear.
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Thread Starter
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From: Overland Park Kansas
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O.K....I found a catalog on Scat's website.
For the Scat9000 1pc RMS:
The 6" crank says internal balance.
The 5.7" says ext/ext -- unless 1pc of Mallory is placed in #1 counterweight. (Then int/stock balancer can be used). That's what you described in another earlier thread btw.
My builder prefers not to use Mallory if possible...so I'm back to an external balancer. Because the problem you described was diagnosed and addressed 2 yrs ago, they and CNC-Motorsports assured me I'd be fine with the 80001 balancer. And, that the Scat assemblies come with that balancer.
So, I'm back to the 80001.
For the Scat9000 1pc RMS:
The 6" crank says internal balance.
The 5.7" says ext/ext -- unless 1pc of Mallory is placed in #1 counterweight. (Then int/stock balancer can be used). That's what you described in another earlier thread btw.
My builder prefers not to use Mallory if possible...so I'm back to an external balancer. Because the problem you described was diagnosed and addressed 2 yrs ago, they and CNC-Motorsports assured me I'd be fine with the 80001 balancer. And, that the Scat assemblies come with that balancer.
So, I'm back to the 80001.
Le Mans Master
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From: Australia
Many of the aftermarket stroker cranks are essential 400 crank castings with 350 journals ( the same as the old way of doing it before aftermarket cranks became available ) so they retain the 400 style ext balance at both ends
FWIW ;
the 1 pce seal forged SCAT crank you refered to in your other post (4-350-3750-5700-L) is a direct factory replacement. Ext at rear / neutral at front ;same as all 1 pce seal engines from factory
FWIW ;
the 1 pce seal forged SCAT crank you refered to in your other post (4-350-3750-5700-L) is a direct factory replacement. Ext at rear / neutral at front ;same as all 1 pce seal engines from factory
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O.K....I found a catalog on Scat's website.
For the Scat9000 1pc RMS:
The 6" crank says internal balance.
The 5.7" says ext/ext -- unless 1pc of Mallory is placed in #1 counterweight. (Then int/stock balancer can be used). That's what you described in another earlier thread btw.
My builder prefers not to use Mallory if possible...so I'm back to an external balancer. Because the problem you described was diagnosed and addressed 2 yrs ago, they and CNC-Motorsports assured me I'd be fine with the 80001 balancer. And, that the Scat assemblies come with that balancer.
So, I'm back to the 80001.
For the Scat9000 1pc RMS:
The 6" crank says internal balance.
The 5.7" says ext/ext -- unless 1pc of Mallory is placed in #1 counterweight. (Then int/stock balancer can be used). That's what you described in another earlier thread btw.
My builder prefers not to use Mallory if possible...so I'm back to an external balancer. Because the problem you described was diagnosed and addressed 2 yrs ago, they and CNC-Motorsports assured me I'd be fine with the 80001 balancer. And, that the Scat assemblies come with that balancer.
So, I'm back to the 80001.
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From: Overland Park Kansas
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Using the balancer option probably means any failure goes against the balancer vs a mallory issue inside the block. IOW, easier to repair w/o the need to disassemble the block.
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Since he guarantees his motors, it sounded like the use of Mallory increased the odds of failure -- specifically that the slug could possibly come loose/shift? Then he went on to say he doesn't do heavy metal slugs. He sends out cranks if slugs are necessary. Maybe he doesn't have that equipment?
Using the balancer option probably means any failure goes against the balancer vs a mallory issue inside the block. IOW, easier to repair w/o the need to disassemble the block.
Using the balancer option probably means any failure goes against the balancer vs a mallory issue inside the block. IOW, easier to repair w/o the need to disassemble the block.
Every builder I ever met prefers the counterweights to be in the crank, rather than hang off the ends of the crank.
Mallory installation is like any part of engine building. If done correctly, it works.
Piston pins are pressed in, and they don't come loose.
For the low powered stuff we all are building, it likely doesn't much matter.
I have run every combination with no troubles.
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From: Overland Park Kansas
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This is for the Scat9000 lightweight (and stronger) cast cranks [aka Pro Comp series]. BTW: This is the 600hp crank.
There is also a Pro Stock series crank (part# 9-103750L) that's listed as factory replacement with int front/ext rear balance. This is the 500hp crank. Maybe you're thinking of this crank?
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From: Overland Park Kansas
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True. OTOH, I got floating pins with bushed rods for my setup!
So,,,,good pistons,,,no Mallory,,,but "cheap" balancer! If it holds,,,my priorities should prove worthwhile!
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Yup...and serious racers all want internal balance vs external too. If the use of Malloy slugs is as strong as a weld (or is welded in), that would seem more reliable/preferable. This shop does seem fairly well equipped, so I'm at a loss why he doesn't/won't do Mallory slugs.
True. OTOH, I got floating pins with bushed rods for my setup!
So,,,,good pistons,,,no Mallory,,,but "cheap" balancer! If it holds,,,my priorities should prove worthwhile!
True. OTOH, I got floating pins with bushed rods for my setup!
So,,,,good pistons,,,no Mallory,,,but "cheap" balancer! If it holds,,,my priorities should prove worthwhile!
Long story short, if a crank breaks and takes out the entire motor, best case is to get a free crank. I used crank as an example. It would apply to any part.
Le Mans Master
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From: Australia
Originally Posted by GREGGPENN
;There is also a Pro Stock series crank (part# 9-103750L) that's listed as factory replacement with int front/ext rear balance. This is the 500hp crank. Maybe you're thinking of this crank?
4340 std weight
Le Mans Master
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From: Australia
A 2 pce seal crank has a big balance weight cast on the crankshaft flange .The engine is called "int " balance because the weight is on a internal part ( the crank ) even though the weight is external to the engine itself
A 1 pce seal engine has a smaller weight on the flexplate thus "ext " balance.
As both masses are in the same location relation to the crank how does the small weight at a distance create a undesirible harmonic that the larger one in close ( int bal ) doesn't ?
I could understand it if the counterweight was machined off the crank flange and engine completely internal balanced
Just trying to get my head around this
Last edited by rodj; Dec 11, 2009 at 09:34 PM.
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Ok so I have asked this question for 10 years
A 2 pce seal crank has a big balance weight cast on the crankshaft flange .The engine is called "int " balance because the weight is on a internal part ( the crank ) even though the weight is external to the engine itself
A 1 pce seal engine has a smaller weight on the flexplate thus "ext " balance.
As both masses are in the same location relation to the crank how does the small weight at a distance create a undesirible harmonic that the larger one in close ( int bal ) doesn't ?
Just trying to get my head around this
A 2 pce seal crank has a big balance weight cast on the crankshaft flange .The engine is called "int " balance because the weight is on a internal part ( the crank ) even though the weight is external to the engine itself
A 1 pce seal engine has a smaller weight on the flexplate thus "ext " balance.
As both masses are in the same location relation to the crank how does the small weight at a distance create a undesirible harmonic that the larger one in close ( int bal ) doesn't ?
Just trying to get my head around this
400's have the flange as a balance pad, and also a weight on the flexplate.
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From: Overland Park Kansas
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Well yeah...the forged series have their own config as well. As I understand it, the 5.7" rod version (that you have) is indeed ext/int. The 6" rod forged version is internal.
That's why I thought I had the correct info (early today) when they were telling me the 9000 series was the same as the forged.
That's why I thought I had the correct info (early today) when they were telling me the 9000 series was the same as the forged.