I read somewhere that the 200 and 250 ci sixes are "naturally balanced." Does this mean that they do not have a harmonic balancer? (I ask because I am trying to rule out possible sources of engine vibration)
They do have a harmonic balancer. All engines are balanced, I don't know about naturally balanced. Is the vibration happens when idling or when the car is moving?
mike- i think i bought a steering gear box from you didn't I....my dad picked it up. The vibration happens when I have the car in idle and take it up to about 1000+ RPM. It vibrates when I go down roads at about 50+ as well. It's kind of a cylical vibration: it won't vibrate for second then it will, repeat.
My car does the same thing, was told it could be the motor mounts. I checked mine and they seem to be bad, haven't replaced them yet as I am waiting on my new motor.
That was my thought the motor mounts could be bad. Thats right on the crank balance. Some engine are internal balance and others are external. Ther internal means the crank is balance and external the fly wheel is balance. Yes you did buy the gear box. Your dad has it.
The 200 , 300 , 250 , 240, 144 and 170 I6s are all internaly balanced. Check and see if the rubber is cracked on the harmonic balancer.
Vibrations while driving at a certain speed are often bad u-joints. Easy to replace. Have the driveshaft rebalanced while it's out of the car too. Rust or a lost balance weight from the driveshaft can cause felt engine vibration. Even a bad tire / wheel balance can feel like it's coming from the engine.
Just to add my $.02 on the balance thing. Most inline 6 and 4 cylinder motors are neutrally balanced. Why? Because there is always the same number of pistons at TDC as there are at BDC (in a 6, there's 3 up, 3 down, 4 cylinders have 2 up, 2 down...at the same time). The weights of each offset the other, cancelling any vibration there might be.
