sb damper

i changed my '69 318 for a '71 318 and i now have vibration throughout the car. i had to change the front timing cover because of the timing mark. i used the '69 damper to match the timing mark. what i am curious about is do the two dampers have the same balance.

Pictures of the balancers would help. It is a bit difficult to understand what you did. Did you change the whole motor, just the balancers and timing covers? The '69 should be a steel crank and internal balance. The '71 could be either I think. The biggest clue is if the '71 has an eccentric weight or not. If it does, it does not interchange with the earlier one.

Weighted torque converter could also be a issue. Depending on what 69Bee said. Short answer swap the balancers and see if the issue goes away. If so then yup there is a difference. If not then you might want to see if the torque converter or flywheel are weighted. Also check your universal joints vibration could be from bad u-joints.

Both are steel cranks. You should be ok with the 69 dampener. Is it seated properly? Do you have any belt misalignment? Which water pump are you using (cast vs alum)? I'm assuming cast so you didn't have to make changes with the hose routing to the radiator. Pre/post '70 use specific water pump pulleys. Food for thought. GL.

gtzperience, you seem to know what i did. i was also wondering if the flex plate and the convertor might be balanced different too. the '71 was mated to a 727 and i put it up to a 904 without changing the flexplate. i just noticed i didn't finish my thought when i originally posted this thread. my car is a '63 belvedere. it was a 6 cylinder car. the '69 motor didn't have this vibration and the 904 was with this motor. i may eventually have to put it back in. everything is new in the car so its not the u joints. the belts all lined up like each other. i do believe i will change the balancers and remark the timing line. it would be pretty maddening to find out it was just the balancer after changing the motor out. argh thanks for all the replies, gary

Both engines are internally balanced and should use the same weighted zero/neutral balanced dampers, flexplates & converters.

Check for converter bolts loose, missing, alignment on the bell, torque converter seated right and deep.