quick internal balance question
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: quick internal balance question (skid)
I have 6" Eagle H beam rods and SRP forged pistons. I don't think they are abnormally heavy parts. My balancer guy says he sees it all the time with the "cheap" cranks.
RACE ON!!!
Racer
Joined: Feb 2004
Posts: 324
Likes: 0
From: Wet Coast
Re: quick internal balance question (CFI-EFI)
What my balance guy sees is supposedly internally balanced cranks that require Mallory to balance out properly (the cheap ones). The "good" internally balanced cranks (Callies, Lunati, etc.) don't require heavy metal. At least that's what I understood.
:cheers:
:cheers:
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Re: quick internal balance question (Surfer69)
thanks for all the help, I'm learning on the fly here. So it sounds like I need to check my (yes) flywheel which I thought was a 168 tooth already, but I will double check. And internal is the way to go then to avoid these problems.
I called my local shop and its around 400 to internal balance new crank. More to do used 400 crank because of the extra journal turning. They said 35 bucks a slug of mallory.
External was 150 but the flywheel situation messes everything up. New custom steel flywheel plus balancing would end up around the same 400.
So I probably will just cough up the extra $ and go internal anyway.
I have to do some thinking about the flywheel.
I called my local shop and its around 400 to internal balance new crank. More to do used 400 crank because of the extra journal turning. They said 35 bucks a slug of mallory.
External was 150 but the flywheel situation messes everything up. New custom steel flywheel plus balancing would end up around the same 400.
So I probably will just cough up the extra $ and go internal anyway.
I have to do some thinking about the flywheel.
My question is why can't you find a SCAT internally balanced crank for your piston rod combo. Can you weigh or have your piston/rod set weighed? What did SCAT customer service say of your combo? Will they measure/wiegh your parts?
David Vizard writes a SCAT crank when matched with the right weight piston/rod combo is balanced good enough to run without additional precision balance. Yes that's the economy of a SCAT crank - just bolt in rotating assembly - same flywheel too.
If your piston/rod combo can't be matched then yes look elsewhere. Shame you can't use the local source (SCAT) though.
I'm interested in how this works out Surfer. Please contiunue to post.
cardo0 :seeya
Drifting
Joined: Sep 2003
Posts: 1,325
Likes: 6
From: FRANKLIN GA
Re: quick internal balance question (cardo0)
Internal or external your crank supplier will have a reccommended bob weight for the crank. The counterweights on the crank are designed for a specific weight. If your pistons and rods weigh more or less than the specified bob weight for your crank it will have to be balanced.
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,720
Likes: 19
From: Manhattan Beach Ca
Re: quick internal balance question (EDDIEJ82)
When I talked to SCAT ( Tom ) a few weeks ago about why there were no internal bal crank for 5.7 rods he told me you cant do internal on the 5.7 rod cranks because of something to do with no room left on the outside of the counterweights to balance. But 6.0 has the ability. Im sure there maybe a custom crank out there but Scat didnt mention anything.
Now I'm wondering if the 30 extra cubes are worth the trouble and cost?
Is there an easy way to tell what flywheel gear I have on the car? I didnt check starter bolts yet.
Now I'm wondering if the 30 extra cubes are worth the trouble and cost?
Is there an easy way to tell what flywheel gear I have on the car? I didnt check starter bolts yet.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: quick internal balance question (Surfer69)
When I talked to SCAT ( Tom ) a few weeks ago about why there were no internal bal crank for 5.7 rods he told me you cant do internal on the 5.7 rod cranks because of something to do with no room left on the outside of the counterweights to balance. But 6.0 has the ability.
Im sure there maybe a custom crank out there but Scat didnt mention anything.
Now I'm wondering if the 30 extra cubes are worth the trouble and cost?
Is there an easy way to tell what flywheel gear I have on the car? I didnt check starter bolts yet.
I'm trying to help, here.
RACE ON!!!
[Modified by CFI-EFI, 9:13 AM 5/25/2004]
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,720
Likes: 19
From: Manhattan Beach Ca
Re: quick internal balance question (CFI-EFI)
OK, I checked starter and I have staggered bolts for sure. If that is a 168 tooth then it would be neutral balanced since it was from stock 350. But 400 flywheels are all external balanced, so what are my options?
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: quick internal balance question (Surfer69)
The staggered bolt pattern IS the one for the 168 toothed flywheel. You knew it was neutral balance, all along, because you have a 350. The 168 tooth flywheels came both neutral AND 400 unbalanced. The problem was going to be that if you had a 153 toother, there was no unbalanced (400) 153 tooth flywheel. Flywheel wise your options are open. If you go for an internally balanced rotating assembly, you use your existing flywheel, starter, and damper. I you go to an externally balanced totating assembly, you will need a flywheel and damper for a 400. You keep your starter, either way. Make sense?
RACE ON!!!
RACE ON!!!
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,720
Likes: 19
From: Manhattan Beach Ca
Re: quick internal balance question (CFI-EFI)
OK, I think we have it all together now. Thanks for everyones help. I probably will have to go external now but will keep thinking about the prices.
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,720
Likes: 19
From: Manhattan Beach Ca
Re: quick internal balance question (Surfer69)
One last question. Cant the 168 balanced flywheel be used as unbalanced by welding on counterweights? Why would I have to get new flywheel for external if I have a 168 tooth and the shop could add weights to it, right?
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: quick internal balance question (Surfer69)
Cant the 168 balanced flywheel be used as unbalanced by welding on counterweights?
RACE ON!!!
Pro
Joined: Oct 2002
Posts: 708
Likes: 0
From: somewhere south of normal
Re: quick internal balance question (CFI-EFI)
This is the balance plate that I think Im will be using on my 383 buildup.....
You still need a 400 balancer, I intend to buy a new 8 incher. This way I can use my 168 tooth 350 flywheel.
https://asp1.secure-shopping.com/jrm...501000,1501005
[Modified by HDIronman, 7:56 PM 5/26/2004]
You still need a 400 balancer, I intend to buy a new 8 incher. This way I can use my 168 tooth 350 flywheel.
https://asp1.secure-shopping.com/jrm...501000,1501005
[Modified by HDIronman, 7:56 PM 5/26/2004]
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,720
Likes: 19
From: Manhattan Beach Ca
Re: quick internal balance question (HDIronman)
Thanks HD, that's what I want plus Summit wants 33 bucks for theirs but their description says with flexplate and doesnt mention flywheel. New 400 ext bal 168 flywheel costs 140 from shop.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: quick internal balance question (HDIronman)
YEP! That's what I'm talking about.
You C3ers have it easy. A 168 tooth flywheel won't fit a manual C4 bell housing, nor will an 8" damper fit without serious frame "adjustments".
Note to Sufer69,
You will have to send your new damper, old flywheel, and new "unbalance" weight, along with the rotating assembly to the balance shop when the time comes.
RACE ON!!!
You C3ers have it easy. A 168 tooth flywheel won't fit a manual C4 bell housing, nor will an 8" damper fit without serious frame "adjustments".
Note to Sufer69,
You will have to send your new damper, old flywheel, and new "unbalance" weight, along with the rotating assembly to the balance shop when the time comes.
RACE ON!!!
