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I finally dropped my '67 at the shop to have the final adjustments and inspections done so I can get it on the road. One of the things I asked them to check is the vibration I am getting from the motor at around 2000-2500 RPM. It happens when the car is in park as well as when it's being driven so I know it's not in the drivetrain. I thought maybe it was a timing/advance issue but now I don't think it is because it starts too easy and is way too smooth at idle speed. The mechanic thinks the motor is out of balance but it hasn't always had the vibration so I don't think it's internal. I know a bad harmonic balancer will also cause a vibration when the internal rubber goes bad. Has anybody had a similar experience? Does anyone know an easy way to tell if the damper is bad? It's one of the large 11 lb. hipo balancers.
 

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Hello.:) I think that the first thing that I would check would be the motor mounts and make sure that one of them wasn't bad or some of the bolts were loose or something. The balancers on the K codes are pretty durable, but it is possible that it's bad. To figure out if it is or not, locate tdc on the # 1 piston manually, by, first, disconnecting the negative battery cable, then removing the spark plug and rotating the motor by the big bolt in the middle of the crankshaft pulley until the piston reaches the top of it's travel. This is best done with a long-stem dial indicator, but, in a oinch, you can stick a new pencil in there, eraser end first and, when the pencil quits getting pushed upward, you're there. Once the piston is at tdc, look and see what the balancer says. It should also be at tdc. If it's more than a couple of degrees off, assuming that you stopped turning the motor as soon as the piston stopped traveling upward, then the outer ring has spun around on you and the balancer is bad. If it does say you're at tdc, start the motor and look and see if the balancer appears to be wobbling any while it's turning. If the the balancer says tdc and doesn't appear to be wobbling, their's nothing wrong with it. :)
 

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Discussion Starter #3
I guess my next question would be why would a motor mount go bad if the car has been sitting in the garage for years? Does the rubber go bad in the mount? Wouldn't that cause a metal to metal chatter? I'm not getting any weird noises, just vibration.
 

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I finally dropped my '67 at the shop to have the final adjustments and inspections done so I can get it on the road. One of the things I asked them to check is the vibration I am getting from the motor at around 2000-2500 RPM. It happens when the car is in park as well as when it's being driven so I know it's not in the drivetrain. I thought maybe it was a timing/advance issue but now I don't think it is because it starts too easy and is way too smooth at idle speed. The mechanic thinks the motor is out of balance but it hasn't always had the vibration so I don't think it's internal. I know a bad harmonic balancer will also cause a vibration when the internal rubber goes bad. Has anybody had a similar experience? Does anyone know an easy way to tell if the damper is bad? It's one of the large 11 lb. hipo balancers.
I've recently had the same experience and have been trying to figure out if the problem is the balancer or something else. The other advice I got was the pinon angle of the rear end is off. I'm not sure how to check that, but I'm going to read the factory manual and see if that could be the problem.:headscratch:
 

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Hi again. :) Yes, the rubber goes bad sitting for years, and, no, you wouldn't have metal-to-metal. Rubber dry rots. Really, time is just as hard as miles on the rubber stuff. I think that I would have someone else start the car while I stood in front with the hood up to see if the motor jumps a little more than it should when the car starts. The pinion angle isn't going to change. If it wasn't doing that before you parked it, it isn't the pinion angle. The bottom line would be that you will need to go around the motor while it's running and pinpoint the point of origin of the vibration. There will be a sound associated with the vibration. Time to break out the stethoscope . :)
 

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I performed the test regarding the indexing of the timing mark and mine is off. Can I safely press it off and reposition it?
 

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Hi again. :) No, you can't. :nogrinner If the outer ring has slipped around some, it's time to replace the balancer. :)
 

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Hi again. :) Yes, the rubber goes bad sitting for years, and, no, you wouldn't have metal-to-metal. Rubber dry rots. Really, time is just as hard as miles on the rubber stuff. I think that I would have someone else start the car while I stood in front with the hood up to see if the motor jumps a little more than it should when the car starts. The pinion angle isn't going to change. If it wasn't doing that before you parked it, it isn't the pinion angle. The bottom line would be that you will need to go around the motor while it's running and pinpoint the point of origin of the vibration. There will be a sound associated with the vibration. Time to break out the stethoscope . :)
Thanks Veronica. I believe my car had this vibration since I've owned it which would be approximately six years ago. It has a different engine in it now and a different rear end and drive shaft. The drive shaft is new and the rear end was built by Currie. It appears at one speed and the mechanic that did a small amount of work thought that is what was my problem. Anyway, I don't want to highjack this thread so I'll stop here.:D
 
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