External Balanced Crank ?
Thread Starter
Instructor
Joined: Jun 2004
Posts: 162
Likes: 1
From: Johnsburg IL
External Balanced Crank ?
I am having a local build a mild 383 for me and he is using an externally balanced crank. My concerns are:
1. I have very limited knowledge
2. He is having to weld wieght to the fly wheel and cut the balancer to get the assembly in balance
3. If the fly wheel or harmoic balancer ever fail would the engine have to be completly torn down to fix? Also, wouldn't welding on the flywheel weaken the metal?
Feedback greatly appreciated!
1. I have very limited knowledge
2. He is having to weld wieght to the fly wheel and cut the balancer to get the assembly in balance
3. If the fly wheel or harmoic balancer ever fail would the engine have to be completly torn down to fix? Also, wouldn't welding on the flywheel weaken the metal?
Feedback greatly appreciated!
Le Mans Master
Joined: Jul 2005
Posts: 5,752
Likes: 4
From: Austin Texas
That is 1 reason to build an INTERNALLY balanced 383....If you need to replace the flywheel or balancer, you are screwed. On mine, the machine shop zero balanced the flywheel and balancer. The welding, if done properly, should be fine.
Safety Car
Joined: Aug 2000
Posts: 3,711
Likes: 43
From: San Antonio TX
A properly-built externally balanced engine is not the issue, but how it's done is. If your "builder" is fiddling with the balance by doing something to the flywheel/flexplate and the damper, you are screwed.
He should put those parts on, spin the crank, and adjust the balance the usual way by adding or removing weight on the crank.
He should put those parts on, spin the crank, and adjust the balance the usual way by adding or removing weight on the crank.
Thread Starter
Instructor
Joined: Jun 2004
Posts: 162
Likes: 1
From: Johnsburg IL
Thanks for the feedback.
Would the flywheel be "0" balanced if done correctly?
I am not sure why he added weight to the flywheel but thought he said to balance the crank. I will check it out.
Would the flywheel be "0" balanced if done correctly?
I am not sure why he added weight to the flywheel but thought he said to balance the crank. I will check it out.
Melting Slicks
Joined: Nov 2003
Posts: 2,362
Likes: 1
From: San Antonio TX
It all depends GrassHopper lol. When you have the correct weighted flywheel and harmonic bal on the engine you can bal it internal depending on how far everything is out. But they are normaly close. But I would check with who ever does bal the assembly as they may do so with just the flywheel and balancer. It all depends on who is doing the work. Also the person that is doing the balance job if they know what they are doing. In the future if you should need a new flywheel or harmonic balancer they should be able to ballance it without taking the engine down to do so. But again please check with who ever you have doing the work. Spin On 
Drifting
Joined: Nov 2001
Posts: 1,469
Likes: 6
From: 68 427 4.11s Roadster
I thought the 454 flywheel was made unbalanced.
To balance you drilled holes from there, or added lead shot to add weight? Isn't this how its done on the counterweights on the crank?
Isn't there an equivilant off the shelf wheel for a 383?
To balance you drilled holes from there, or added lead shot to add weight? Isn't this how its done on the counterweights on the crank?
Isn't there an equivilant off the shelf wheel for a 383?
Race Director
Joined: Dec 1999
Posts: 16,945
Likes: 9
why would he have to weld weight to the flywheel when you can just buy & install this: (you do need the ext. balance damper)
http://www.speedwaymotors.com/xq/asp...qx/Product.htm
http://www.speedwaymotors.com/xq/asp...qx/Product.htm
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Melting Slicks
Joined: Nov 2003
Posts: 2,362
Likes: 1
From: San Antonio TX
Yes the 454 flywheel and balance is made unbalanced. They come that way.
Twin Turbo is correct as you could use what he posted for a flywheel that was not made for the 454 or 400 SB. But you would still need the correct harmonic balance.
would like to add if you worry about something like this at a later date you can purchase an aftermarket crank shaft that is internally balanced. As to make an externally balanced crank internal is costly because of all of the work it takes to make it so.
Twin Turbo is correct as you could use what he posted for a flywheel that was not made for the 454 or 400 SB. But you would still need the correct harmonic balance.
would like to add if you worry about something like this at a later date you can purchase an aftermarket crank shaft that is internally balanced. As to make an externally balanced crank internal is costly because of all of the work it takes to make it so.
Last edited by SHAKERATTLEROLL; Jul 30, 2005 at 10:28 AM.