balancing a 400
Thread Starter
Melting Slicks
Joined: Jan 2003
Posts: 2,804
Likes: 1
From: OKC Oklahoma
balancing a 400
So my parts got dropped off to get balanced. I'm letting a friend build the short block, so he dropped them off this morning. The crank is an intenally balanced Scat, the rods are 6" Eagle lightweigth SIR, and the pistons are KB hypereutectics. The cylinders are already honed for these pistons and rings. Well the shop looks at the parts and says they won't intenally balance. He says my pistons are too heavy. Anyone have a 400 interntally balanced?
Thread Starter
Melting Slicks
Joined: Jan 2003
Posts: 2,804
Likes: 1
From: OKC Oklahoma
I've looked at some othe manufacturers and their forged pistons seem to be heavier than my KB's, so I'm wondering if the guy just didn't want to do it or he doesn't know what he's talking about. The KB's are 430 grams and the pins are 145 grams. 4.165" bore.
Melting Slicks
Joined: Jan 2004
Posts: 2,672
Likes: 1
From: New Cumberland PA
I have no idea how they balance things other than they weigh pistons and rods to get them relatively the same weight. I purchased a 383 externally balanced stoker kit, with flexplate and damper, from a local machine shop/engine builder who balanced it. I thought the fee of $180 was high for balancing but I knew I could not do it.
Melting Slicks
Joined: Dec 2001
Posts: 2,025
Likes: 1
From: Billings MT
I have the Scat 9000 series crank in my 406 with Scat 6.0" H-beam rods and SRP flat top pistons. The rods weigh 650 grams, the pistons weigh 424 grams. It was internally balanced with no Mallory metal required.
Thread Starter
Melting Slicks
Joined: Jan 2003
Posts: 2,804
Likes: 1
From: OKC Oklahoma
Originally Posted by VETDRMS
I have the Scat 9000 series crank in my 406 with Scat 6.0" H-beam rods and SRP flat top pistons. The rods weigh 650 grams, the pistons weigh 424 grams. It was internally balanced with no Mallory metal required.
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Team Owner
Joined: Feb 2003
Posts: 30,183
Likes: 313
From: Lake Norman NC
Mike, I'm running an Eagle crank, same rods, and KB pistons...in my 383...all internally balanced and no mallory metal added to the crank. Sounds like this guys is giving you a bunch of bs. strange. 
Safety Car
Joined: Feb 2002
Posts: 4,286
Likes: 4
From: Guam
Yes, if all the pistons, rods and pins weigh the same, internal balancing is no problem. But if they have deviations, some extra work is needed. If you bought a crank that is already balanced, then the hard work is already done. So I am not sure what he is talking about. I suppose that he really does not know how to perform the work. Balanced cranks only require working with the pistons, rod, pins, and rings. It is not that complicated.
Racer
Joined: Dec 2001
Posts: 328
Likes: 0
From: Dallas County Texas
Not only is my 413 Internally balanced he got it to under
a half gram....gross bobweight was something like 1875g.....
...so much so he advised to not use a balancer at all (just a center hub) - which I didn't, but after some other major screw ups will be adding one shortly.
Mine did require some Mallory metal, but not much - on two weights I believe.
I have a crank from Eagle (I think the 4340 one...) and their H Beam rods with some Diamond custom nitrous designed ones. I also have the AARP L19 fasteners throughout and splayed 4-bolts (all studs where possible.)
Several agreed with the no balancer and I had heard of it before, but these are drag folks who think 10 run hours between rebuilds is amazing, so I won't be staying with that ssetup and will add a neutral balance FlowDampr or TCI Rattler.
(This genius also thought a bronze gear was a good idea on a cam that did not call for it - Comp Cams didn't agree and neither did the engine less than 2K miles later....)
...so much so he advised to not use a balancer at all (just a center hub) - which I didn't, but after some other major screw ups will be adding one shortly.
Mine did require some Mallory metal, but not much - on two weights I believe.
I have a crank from Eagle (I think the 4340 one...) and their H Beam rods with some Diamond custom nitrous designed ones. I also have the AARP L19 fasteners throughout and splayed 4-bolts (all studs where possible.)
Several agreed with the no balancer and I had heard of it before, but these are drag folks who think 10 run hours between rebuilds is amazing, so I won't be staying with that ssetup and will add a neutral balance FlowDampr or TCI Rattler.
(This genius also thought a bronze gear was a good idea on a cam that did not call for it - Comp Cams didn't agree and neither did the engine less than 2K miles later....)