| Here is an article I came across recently regarding SBF balance, |
Small Block V8 Balancing |
There Is More Than Meets the Eye In the November-December 2007 Fairlaner magazine, I men- tioned that the 289 HiPo damper and extra counterweight could replace the standard 289 damper. This was based on information from Ford’s 1969 Muscle Parts catalog. However, I have subse- quently found out new information on counterweighting for the Ford small block V8 in extensive conversations with Des Ham- mill. Des is compiling a history of the Ford small block V8 which he hopes to publish this year. Essentially, anytime there was a change in the rotating or reciprocating mass on the Ford small block V8, the external counterweighting was changed because the crankshaft was not. The 221 V8 had the least reciprocating weight due to the small pistons. The heavier pistons of the 260 required increased exter- nal counterweight. In 1964 production, the 260 switched to the 289 connecting rods, which increased both reciprocating and rotating mass, thus the need for more external imbalance. The 289 required even more because of its heavier pistons. And, the 289 HiPo had the most counterweighting because of the heavier connecting rod bolts, nuts, and caps. The differences were not too great and can easily be accom- modated by a good engine machinist during rebuild. However, Ford sold parts as direct replacements, so it used unique part numbers for each application. So, if you are changing dampers or flywheels/flex-plates on the 221, 260, 289, or 289 HiPo, you have to be careful not to upset the factory counterweighting by swapping components between the following groups of engines: 1962-63 221, 1962-63 260, 1964 260, 1963-68 289, and 1963-67 289 HiPo. For dampers, identification of the various components is straightforward. The 221 V8 is easiest. It did not use a harmonic damper, but instead used a pulley adaptor. All the 221 V8s used the same counterbalanced adaptor. The 260 V8 used two different dampers. One was used for 1962-63 production and will carry one of three casting num- bers — C2OE-6316-A, C2OE-A, or C2OE-6316-B. Each of these dampers can be interchanged. The second damper carried the number C4OE-A1. It was used in 1964 production and has dif- ferent counterweighting than the others. 1962-63 221 & 1962-63 260 1963-68 289 & 1964 260 The 260 V8 was the only Ford small block to use two different connecting rods. In 1962-63 it used the 221 rod, but switched to the 289’s in 1964. The standard 289 dampers (all but the 289 HiPo) can all in- terchange. The casting numbers were C3AE-F, C4AE-C, C4AE- 6316-B, C5AE-A1, C5AE-6316-A2, and C8ZE-B1. Likewise, the 289 HiPo dampers can interchange with each other. There were only two production dampers—C3OE-B and by Bob Mannel C5OE-A. The service replacement damper was C8ZE-A, but it had a different appearance. The 289 HiPo damper contained only part of the counterweighting. The rest was in the extra counter- weight mounted in front of the number one main bearing. Interestingly, the 289 HiPo damper by itself was counter- weighted exactly like the 1962-63 260 V8. In other words, you could substitute a 289 HiPo damper (without the extra counter- weight) in place of the 1962-63 260 damper and maintain proper engine balance. As mentioned, all these engines used the same crankshaft, except for the 289 HiPo, which used a crankshaft formed in the same mold, but made with a higher nodular cast iron. All these crankshafts were statically in balance — meaning they had no heavy side. But the counterweights at each journal pair (cylinders 1-5, 2-6, 3-7, and 4-8) did not balance with the connecting rods, bearings, and piston assemblies at those journals. Additional counterweighting was required externally and was done through imbalance at the damper and flywheel/flex-plate. The subject of how much counterweighting a particular engine needed was a very complex problem. Determining how much of a connecting rod was rotating mass and how much was re- ciprocating was just part of the complexity. There were dynamic factors to consider as well. These factors included the effects of pressure (or lack of it) on the pistons, friction of the piston rings, and more. However Ford did it, it did so by imbalance at the damper and flywheel/flex-plate. Most machine shops today balance crankshafts by using bob- weights at each crankshaft journal equal in weight to 100% of the rotating weight and 50% of the reciprocating weight. There is no perfect solution as the problem is too complex. But, over the years, this formula has proven to minimize engine vibration in most cases. Dividing weight between rotating and reciprocating is not particularly accurate either. The piston, rings, and piston pin are pure reciprocating. The connecting rod bearings and little bit of oil in the crankshaft journey passage are pure rotating. But, the connecting rod is both rotating (big end) and reciprocating (small end). Generally, the connecting rod weight is split by weighing the rod with its axis horizontal while suspending each end at the centerlines of small and large holes. The weight recorded at the large end is considered rotating weight, while the other end’s is reciprocating weight. It is not a perfect method, but works well with the formula for most stock engines. So, the weight to be added at each of the four connecting rod journeys as bobweights for balancing included the weight of the rod bearings for both associated cylinders, rotating weight of both connecting rods, and oil weight in the crankshaft journey passage. This is 100% of the rotating weight. Plus, one piston with piston pin, one set of rings, and one connecting rod’s re- ciprocating weight. This is 50% of the reciprocating weight. (You could add both pistons with pins, both ring sets, and both rod’s reciprocating weight, then take 50% of that to arrive at the same reciprocating weight.) Since the counterweights on the crankshaft were the same for all our engine applications, but the weights associated with pistons and connecting rods varied between the five groups of 12 January-February 2008 j |
engines (1962-63 221, 1962-63 260, 1964 260, 1963-68 289, or 1963- 67 289 HiPo), Ford changed the counterweighting of the damper and flywheel/flex-plate to compensate.
To keep the crankshaft in static balance, when counterweight was added to the flywheel/flex-plate, an equal amount of coun- terweight was added to the damper on the opposite side of the crankshaft (weights were 180 degrees apart). So, although we often hear about a flywheel being a “28.2 ounce,” we are really talking about a flywheel with a 28.2 ounce-inches (oz. in.) imbal- ance on one side, which was countered by a damper with 28.2 oz. in. imbalance on the opposite side of the crankshaft. This kept the crankshaft in static balance while compensating with the need for increased or decreased counterweighting.
So, when dealing with the small blocks using the same crank- shaft, we have to keep the damper and flywheel/flex-plate together as a set within the appropriate engine group. The table above shows the sets of components that are compatible and how to identify them.
The 302 V8 has not been mentioned until now. It used a dif-
ferent crankshaft, so its counterweighting was not the same as the 221-260-289 series. However, Ford designed the crankshaft so that the external counterweighting would match that of the 289 (28.2 oz. in.). This meant that Ford could use the same fly- wheel/flex-plate on both the 289 and 302. Ford did not use the same damper on the 302 as on the 289 because the 302 needed increased dampening weight to better control vibrations of the larger displacement engine. But, it does mean that you can use a 302 damper on a 289 without changing engine balance while gaining the advantage of the 302’s better dampening.
In conclusion, the division in 302s between 28 or 50 ounce fly- wheels has led many people to believe that all Ford small block V8s before the 302 used 28 ounce flywheels. But, now you know that is not true. Only the standard 289 used the same 28.2 oz. in. flywheel as the 302. When dealing with the early engines, the external coun- terweighting was different between engine groups and involved both the damper and flywheel/flex-plate. This is important when swapping parts. However, they are close enough to each other that a machinist can balance an engine using any of them. f
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