Flywheel

It is a common casting used from 1963. My memory is not too precise in this area, but I think you can find them on any small block from about mid-63. Since they were balanced for the engine, one casting was good enough, I suppose. I know there was a C2OE in 1962. My 63 HiPo has the same C3OE casting.

There is some confusing info out there on this subject but as Bob noted the C30E-6380-B flywheel is not HiPo specific. However, AFAIK only HiPo's should have a specific version of this flywheel which is balanced differently than the standard 289 version and will have a Brinnel hardness test mark and, if it's never been hot-tanked, an orange paint daub. I've never seen a non-HiPo flywheel without the test mark.

Since your's still has a 160 tooth ring gear I assume it's the original flywheel. The 160 tooth gear was replaced by the 157 tooth gear sometime in that late 60's.

If possible please post some pics of your flywheel.

Both Hipo & regular 289 used the same C3OE-6380-B flywheel casting.

The Hipo flywheel was balanced to 30.4 oz.in. while the regular 289 was balanced to 26.2 oz.in. When Ford went to 28 oz. balance for the regular 289 they changed the casting number.

In the process of installing the correct transmission for my kar I also changed out the flywheel as my original had severe heat cracks and had been turned down all the way. I took it to the balance shop to have the replacement matched to it. The residual imbalance on the original flywheel was 32.5 oz.

Terms must be defined. There really is no such thing as a 28 ounce flywheel or a 50 ounce flywheel, etc. It is meaningless except as a label. With imbalance you are dealing with a torque. Torques are applied forces at a distance from the center of rotation. For our engines, you are dealing with ounce-inches, abreviated as oz. in. or oz-in. One ounce inch (oz-in) means that there is a one ounce force applied tangentially at one inch from the centerline. When we say there is a 30.4 oz-in imbalance on the flywheel, it means that there is a 30.4 ounce force applied at one inch from the center line (30.4 x 1 = 30.4). This is identical to a 15.2 ounce force applied at 2 inches (15.2 x 2 = 30.4), or a 7.6 ounce force at 4 inches (7.6 x 4 = 30.4). In the case of the flywheel, the weight is spread throughout a trapazoid-shaped cast-in weight at various distance from the centerline, but when summed up, equals 30.4 oz-in. In short, there is a 30.4 ounce tangential force at 1 inch trying to turn the flywheel when the flywheel counterweight is at the 3 or 9 o'clock position.

For example, if you had the flywheel mounted on a free-turning shaft (shaft and flywheel centerline perfectly matched), and positioned the flywheel weight at 3 or 9 o'clock, then measured with a scale the force the flywheel would apply as it attempts to rotate so that the heavy side is down and you resisted the flywheel at a point that was 5 inches from the centerline, the scale would read 6.08 ounces. The torque would be 6.08 x 5 = 30.4 oz-in.