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Has anyone heard of a 383 being built using a 350 flywheel instead of an ext. balanced 400? I hadn't, but when I visited my engine builder today one of the guys pointed out that I had been using what appears to be a 350 flywheel. He showed me how a 400 flywheel has a balancing weight cast into the backside of it and mine did not have that. My flywheel also had some drilling done near the edge on the backside that was obviously done for balancing. What I'm wondering is could this motor have been originally built with a 350 flywheel that was drilled along one edge to make up for not having the weight cast into it like a 400 flywheel? BTW, this motor will be externally balanced.
They recommended I ditch this and pick up a 400 flywheel. Any opinions on this?
 

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my 383 is internally balanced and uses a 350 style balancer and flywheel. If you have a external balanced 383 you will need a 400 balancer and flywheel.
 

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66dave said:
my 383 is internally balanced and uses a 350 style balancer and flywheel. If you have a external balanced 383 you will need a 400 balancer and flywheel.
That's what makes this strange, this was an externally balanced 383 but seems to have had a 350 flywheel. I think this motor may a bit different anyway just because it was built so long ago (about 17 years ago) when 383's weren't so common and maybe the 'stroker science' wasn't as perfected. For example, this motor also used the shorter 400 rods so the block had not been clearanced around the pan rails.
 

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I am no pro on ballancing engines but When I took my 383 parts to the machine shop two years ago, I asked for it to be internally ballanced so I could use a standard 350 flywheel. They told me that they would ballance it for that but I would still need to use a 400 damper out front. This is the best machine shop in town so I trusted them even though it sounded strange...Everything worked out perfect when I started it up. So I would leave the original flywheel on if you dont have a vibration.

my 2c
Frank T
 

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Fatcat said:
I'm with Frank on this one, the thing should have shook your fillings loose if it wouldn't have been set up to use the neutral flywheel, leave it as is.
My crank has already been re-balanced for the new rods & pistons to work with a standard external balance 400 flywheel, so now I will have to buy one.
 

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I'm putting together a 383 with an EAGLE rotating kit. It's a one piece rear main seal kit and it uses a standard 350 one piece seal fly wheel. I believe a kit that uses a 2 piece seal will need a 400 fly wheel unless the machinist balances it so it doesn't.

Ron
 

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My crank has already been re-balanced for the new rods & pistons to work with a standard external balance 400 flywheel, so now I will have to buy one.

When they balanced it they should have used the same balancer and flywheel that you are going to be using on the motor. That is the only way to get a true balance.
The guy that did mine even wanted the bearings and rings I was going to use also.
 

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I have seen three different balancing methods of the common chevy 383, internal or neutral balance, common 400 style external balance, and the external balance hub with a neutral flywheel/flex plate....

Plus like stated before.. an netural balance flex plate can be balanced to external spec...

Good luck
Veno
 
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