318 magnum vibration.

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Rick Wellman

Rick Wellman

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i put a 2000 model 318 magnum in my 65 cuda. Bought a flywheel and bellhousing off FABO. Have a vibration in the engine. At 3000 rpms it vibrates pretty bad. How can I tell if I have the wrong flywheel. Are there numbers on the flywheel. I’ve heard that 318 magnums are externally balanced.
 
The 5.2(318) magnum is internally balanced, the 5.9(360) is externally balanced. So two possible ideas are:
Maybe you have a 5.9 and not a 5.2
Maybe that flywheel came off an LA 360.
 
Did the flywheel look solid (ie. no scallops cut out or weights added?) EVERY 318 was neutral balanced.
Chrysler Small block



  • 318 A (POLY)-Internal
  • 273-318-340 (340 to 1971 Steel Crank) LA-Internal
  • 340 (1972 up w/Cast Crank) External
  • 360-External


Chrysler MAGNUM Engine



  • 318 (5.2) Internal
  • 360 (5.9) External
  • 5.7l, 6.1l, 6.2l, 6.4l HEMI- Internal
 
I ran the numbers and it is definitely a 318 magnum. I pulled the engine from a 2000 dodge van. I bought a flywheel from Tony’s Parts on FABO. It bolted right up. Could he have sent me a 5.9 flywheel ? How do I tell the difference in a 5.2 and a 5.9 flywheel ? There are no scallops or added weights on the flywheel. Thanks for you guys replying. Rick
 
Did you change the harmonic damper to an aftermarket unit? They are also specific to internal/external balance.
 
Rick Wellman said:
I ran the numbers and it is definitely a 318 magnum. I pulled the engine from a 2000 dodge van. I bought a flywheel from Tony’s Parts on FABO. It bolted right up. Could he have sent me a 5.9 flywheel ? How do I tell the difference in a 5.2 and a 5.9 flywheel ? There are no scallops or added weights on the flywheel. Thanks for you guys replying. Rick
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What are the differences between 318 Magnum and 5.2 Magnum? I thought 318 was LA engine and 5.2 was Magnum.
 
They are just interchanging terminology. Magnums all used the size designation in liters, so 5.2 Magnum is 318 cubic inch Magnum and 5.9 Magnum is 360 cubic inch Magnum.
Balanced parts, like harmonic balancers, flex plates or flywheels, and cranks, roads, and pistons are specific to each family of engine, unless the parts are balanced properly before use.

Edited to remove LA engine from last paragraph.
 
Last edited:
Maistrelli said:
What are the differences between 318 Magnum and 5.2 Magnum? I thought 318 was LA engine and 5.2 was Magnum.
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The 318 magnum is a 5.2 magnum. No difference. Just my terminology. I’m old school and still use the cubic inches instead of liters.
 
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