BBC Vibration

7

77HAWAIIAN

New member
I have a 496 that has been completely rebuilt about 3 months ago. Everything in the motor is new and balanced as I was told. The motor has a bad vibration around 2000 rpm but smooths out at a higher rpm but still noticeable. There is no akward noises that can be heard. I removed the drive shaft from the pump to eliminate it and the valve springs all looked good.Anybody got any suggestions or ideas. Thanks :smile18: :smile21:
 
mrgoslow

mrgoslow

New member
Duanehydro said:
Suggest not running it until you find out what's up. Can cause engine damage.
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i'll second that. i ran a bbc years ago with a cracked flywheel. barely noticeable vibration. finished the season before pulling to investigate. didnt blow it but it hammered on the bearings. i almost positive it wasnt my foot that did it :smile14: anywho, check it unless you wanna get out the check book. oh wait, you'll have to do that anyway
 
duanehydro

duanehydro

Active member
that's a thought...did the flexplate bolt up evenly and straight? and not maybe on backwards? If that's possible.
 
J

jerjrvette

Member
HISTORY LESSON/REMINDER: 396 AND 427 CRANKS ARE INTERNALLY BALANCED AND 454 IS EXTERNALLY BALANCED. THE BALANCER/DAMPNER ON A 454 WILL HAVE A COUNTER WEIGHT ON THE MOTORSIDE OF THE OUTER RING AND THE 396/427 WILL NOT. THE FLEX PLATE ON THE 454 WILL HAVE SMALL WEIGHTS WELDED ON NEAR THE RING GEAR. THE ONLY LONG SHOT I WOULD GUESS AT, IS THE STARTER BENDIX IS NOT DISENGAUGING UNTIL YOU SHUT DOWN! ANY NOISE WHEN CRANKING? JUST A SHOT IN THE DARK. GOOD LUCK ,JERRY :smile21: :smile24:
 
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