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Old 10-16-2012, 10:06 AM
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Newly Built 383 Engine Vibration. Did i pick the wrong flywheel?

Just had built a 383 stroker

GM 1 piece rear main seal block
Eagle Rotating assembly kit (4.030X3.750 5.7 Rod, -18CC inverted dome) PN: Eagle B13004L Eagle Street and Strip Rotating Assembly

The kit came with everything including harmonic balancer and flex plate. I didnt need the flex plate because the transmission is 4 speed manual.

I used flexplate JEGS Performance Products 601250 JEGS Flywheels
Its a 153 tooth external balance flexplate for 350 chevy 1 piece rear main.

I now have severe engine vibration and gets worse as RPM increases.....

Any thoughts??

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Old 10-16-2012, 10:41 AM
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Take the flywheel and the flexplate to an automotive machine/balance shop and have them weight matched to your application.

Common job.
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Old 10-16-2012, 12:00 PM
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Yep wrong flex plate 383/400 needs balanced flexplate. If you used std trans setup for 350 its the wrong one. Call the guy you got the kit from and tell him what happend. they should be able to provide the correct part number. Eagle has the correct part on the shelf but its got to come apart. You can also call them and tell them what parts you used instead of the kit parts. They do make one for std trans. Just got to get those parts. i think its just a lump of metal you can bolt on. But not sure if that is a proper way to fix the issue.

Also a shop balancing the engine is the correct way to go. Balanced kits can usally just be run but it is best to balance it for high rpm running. This is not the same type of balance that is on the flywheel or harmonic balancer. Lots of info out there. You will have to dig around the net to find out what is right for you. Look up "383 internal or external balancing" in google.


Do not drive it by the way. That can damage it further. If you have to drive it keep the rpm below 2K for a short trip. I would not drive it sep into the garage. Sorry i know it sucks to have to pull it back apart again. But you may be able to just drop the trans off the mounts and install the new setup.

Hope this helps!
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Old 10-16-2012, 04:41 PM
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Quote:
Originally Posted by 06-z0sick View Post
Just had built a 383 stroker

GM 1 piece rear main seal block
Eagle Rotating assembly kit (4.030X3.750 5.7 Rod, -18CC inverted dome) PN: Eagle B13004L Eagle Street and Strip Rotating Assembly

The kit came with everything including harmonic balancer and flex plate. I didnt need the flex plate because the transmission is 4 speed manual.

I used flexplate JEGS Performance Products 601250 JEGS Flywheels
Its a 153 tooth external balance flexplate for 350 chevy 1 piece rear main.

I now have severe engine vibration and gets worse as RPM increases.....

Any thoughts??
I run everything though the balance shop, as things stand now you have no way of knowing if the rotatating assembly sans damper and flywheel can be balanced with the damper and flywheel you have or with anyother for that matter. The whole assembly has to be balanced in that the rods and pistons equalized to each other, then spun with the damper and flywheel to determine where on the crank, damper and flywheel adjustments need to be made. Never, ever trust the balance from these kits and don't buy them as balanced they often don't come close making that extra cost a total waste of your money. Buy the pieces install and check clearances as often you have to grind on the rods and pistons with these stroker kits, check the valve to piston clearance as that may require grinding on the piston. Then take it apart and send all the pieces damper and fly/flex even if they are supposed to be neutral balanced they often aren't.

Bogie
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Old 10-17-2012, 06:42 AM
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That kit just says its externally balanced meaning flywheel or flex plate and balancer or weighted, It does not say its balanced ready to go.
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