There has been lots of talk in the past about balance comparisons of the 6.9/7.3.
I had my new longblock balanced when I did the build on it. Problem was it was balanced with a dampener and flywheel to match up with a T-19. Now, I'm looking at a cavitated 7.3 on a E4OD, and trying to figure out what to do balance wise to mate my new engine to the automatic without upsetting the balance. So, I got in touch with the guy who balanced my engine originally and who does this for a living, and is regarded as the guy to go to by most shops in the area.
He said, that simply, the 6.9 and 7.3 come from the factory balanced "close enough" to run. However, they can be out by as much as a few ounces if you figure all the parts that are turning.
The crankshaft on the 6.9 and 7.3 are the same part number. However, that's where the similarities end. The dampener is different to both. The flywheels are balanced differently for both, and are also different for the Standard and automatic for both. They should not be interchanged without being rebalanced
So, when he balances an engine here is what he does. First, he weighs the internals and grinds/shaves them to weigh exactly the same as the lowest part. This includes connecting rods(each end done separately) and pistons. Then he spins them on the crank and balances the whole assembly. Then he puts on the dampener(which is indexed) and the flywheel and balances the whole rotating mass.
He said that although he knows of guys swapping parts, if not done correctly, it will never be in balance. Since these engines spin at relatively low rpms, the difference may not be that noticeable, but they will definately not be balanced.
So, he says that I should be able to give him the flexplate from the E4OD and he can match it to my present flywheel that he used to balance the engine, then the whole thing will be in balance.
I asked him about swapping a zf5 into an older truck with the 6.9 and solid flywheel. He said that the zf5 doesn't care what flywheel is in front of it, but that if the engine that was there before was balanced and the engine being swapped in was balanced, then there will be no problem. However, if parts from one engine are used on another, then they must be balanced to match.
All this stuff came out of the 1987 7.3L diesel engine technician's update, which was used to quickly bring up to speed a 6.9 diesel mechanic.
Flywheel -
IMPORTANT. DO NOT USE 6.9 flywheel or vibration damper on 7.3 or vice versa. If components are intermixed, engine vibration and premature component wear may be encountered. For identification, compare these part numbers.
Vibration damper 6.9 1805414C1
Vibration damper 7.3 1809117C1
Flywheel Auto 6.9 1803219C1
Flywheel Auto 7.3 1809212C1
Flywheel manual 6.9 E7TA-6477-AB
Flywheel manual 7.3 E8TA-6477-AA
Zigg /ubbthreads/images/graemlins/smile.gif
I had my new longblock balanced when I did the build on it. Problem was it was balanced with a dampener and flywheel to match up with a T-19. Now, I'm looking at a cavitated 7.3 on a E4OD, and trying to figure out what to do balance wise to mate my new engine to the automatic without upsetting the balance. So, I got in touch with the guy who balanced my engine originally and who does this for a living, and is regarded as the guy to go to by most shops in the area.
He said, that simply, the 6.9 and 7.3 come from the factory balanced "close enough" to run. However, they can be out by as much as a few ounces if you figure all the parts that are turning.
The crankshaft on the 6.9 and 7.3 are the same part number. However, that's where the similarities end. The dampener is different to both. The flywheels are balanced differently for both, and are also different for the Standard and automatic for both. They should not be interchanged without being rebalanced
So, when he balances an engine here is what he does. First, he weighs the internals and grinds/shaves them to weigh exactly the same as the lowest part. This includes connecting rods(each end done separately) and pistons. Then he spins them on the crank and balances the whole assembly. Then he puts on the dampener(which is indexed) and the flywheel and balances the whole rotating mass.
He said that although he knows of guys swapping parts, if not done correctly, it will never be in balance. Since these engines spin at relatively low rpms, the difference may not be that noticeable, but they will definately not be balanced.
So, he says that I should be able to give him the flexplate from the E4OD and he can match it to my present flywheel that he used to balance the engine, then the whole thing will be in balance.
I asked him about swapping a zf5 into an older truck with the 6.9 and solid flywheel. He said that the zf5 doesn't care what flywheel is in front of it, but that if the engine that was there before was balanced and the engine being swapped in was balanced, then there will be no problem. However, if parts from one engine are used on another, then they must be balanced to match.
All this stuff came out of the 1987 7.3L diesel engine technician's update, which was used to quickly bring up to speed a 6.9 diesel mechanic.
Flywheel -
IMPORTANT. DO NOT USE 6.9 flywheel or vibration damper on 7.3 or vice versa. If components are intermixed, engine vibration and premature component wear may be encountered. For identification, compare these part numbers.
Vibration damper 6.9 1805414C1
Vibration damper 7.3 1809117C1
Flywheel Auto 6.9 1803219C1
Flywheel Auto 7.3 1809212C1
Flywheel manual 6.9 E7TA-6477-AB
Flywheel manual 7.3 E8TA-6477-AA
Zigg /ubbthreads/images/graemlins/smile.gif
