| Some of
you may know that I have plans to convert my Buick straight-eight from
carbs to EFI. Not only that, but I'm going to install a Procharger
centrifugal supercharger! Why? Because it's fascinating, and
there's nothing readily available, so there's lots of pioneering and
fabricating involved. I've seen turbocharged and
roots-supercharged straight-eights, but not one with a centrifugal
supercharger. And so far I don't know anyone who would have succeeded
in making a sequential EFI system work with siamesed intake ports... The original Buick vibration damper (call it harmonic balancer or harmonic damper, your choice) is a slip-fit unit which is constructed of multiple layers of steel discs. It may have worked well as new, but decades of rust have probably frozen the discs onto each other. And, the Buick damper is very loose fit over the crank snout, so I doubt that the hub is able to transfer that vibration to be dampened. I'm going to make serious power, so I was looking to upgrade this component to something more modern. Kudos to Jeff Brock from across the pond, who told me that the Oldsmobile damper would fit the Buick with minor modifications. By the way, Jeff built a record setting '52 Super salt flats racer. Thanks, Jeff! While pondering my options as how to arrange the 8-rib crankshaft pulley to drive the supercharger, I discovered there's no room for an additional pulley between the damper and the radiator. But then I found that ATI Performance Products makes a damper for Chevys that features a 8-rib belt pulley integrated into the outer shell. Ingenious! |
 This is a custom damper that I ordered from ATI. It consists of an Oldsmobile hub (p/n 916760) and a Chevrolet outer shell with a 7.5" outside diameter (p/n 917025). Just perfect for driving the Procharger P-1SC supercharger! Oldsmobile dampers were all externally balanced from the factory, but neutral balanced dampers are available from the aftermarket. Beware or the cheap overseas dampers, as they are known to be more or less out of balance, or in some cases, may break apart at high loads, although claimed to be "SFI approved" Ideally, a balancer should be matched to the engine. The critical frequencies of a straight-eight (long crank & stroke, heavy reciprocating masses) are probably lower than the frequencies of a V-8. So this is a long shot. It may work. If this was a race engine, with sustained high-rpm use, the balancer should be designed just for this engine, either by using a simulation software or by actual testing. Companies like BHJ Dynamics are able to do that. But this is a street engine, so I will take my chances. |
 Both the Buick and Oldsmobile crank snouts measure 1.5 inches. All ATI hubs are intended for a press-fit to the crankshaft in order to properly transfer the harmonics, and the instructions tell you to hone the ID for a proper fit. The recommended interference is 0.0007" to 0.0009". It turned out to be 0.0005" with the Buick 320 crank snout, no need to hone at all. Sink the hub in boiling water just prior to installation, and you can get it started on the crank snout by hand, before it cools off and shrinks back. Doing so will allow you to rotate the hub to find the key position! Once the hub cools off and and grabs to the crank snout, you'd better have the key in the keyway, as there's no turning the hub anymore. Using boiling water to heat the hub will ensure that the heat won't damage the lip seal upon installation. |
 This is a 2-groove billet pulley that I used with the original Buick damper (the four extra holes reminding). It's for a Chevrolet small-block short water pump system. The inside diameter of the pulley was machined to be a snug fit over the Oldsmobile hub. ATI makes the Olds hubs with a Chevy bolt pattern, so that wasn't an issue. Those three bolts screw into the hub, and protrude thru the hub and outer shell (see picture below). The Oldsmobile hub measures 2.00" at the seal, while the Buick 320 hub measures 2-1/16". So you need to find a new seal that measures 2.00" ID by 3.00" OD. Not so easy in a metric country. I did find a suitable seal - it's a National p/n 410085 and it's not a balancer seal, but supposedly a transmission output shaft seal for a GM application? In addition, you need approximately a 1/2-inch longer balancer bolt, as the Buick bolt locates deeper in the hub. And you also need a thick washer under the bolt, with a larger 2" OD. |
 The balancer came with a bolt pack p/n 950200, including six smaller bolts required to bolt the hub and outer shell together (using blue Loctite), and three larger bolts to bolt on a pulley. Although I used my own, very long bolts, and screwed them in from the "wrong" side. This way I can bolt the V-belt pulley on the other side, and a trigger wheel on this side, using the same three bolts. |
 This is a 60-2 Trigger Wheel for the EFI. The two missing teeth will tell the controller the position of the crankshaft in relation to Top Dead Center (TDC). Four teeth would be enough, while 12 teeth would be optimum. In principle, the more teeth, the better the accuracy. But in reality, there can be too much of a good thing. The more teeth, the better chance of misread at high rpm's. I chose this 60-2 wheel because it's 8 inches in diameter, and fits my bill perfectly. The center hole was turned to fit snugly over the collar on the damper hub. There shouldn't be any runout , as the trigger pickup must be really close the the wheel. I'm using an inductive (reluctor) pickup that is a Ford (European) p/n 948F6C315AA I welded a simple bracket on the timing cover to mount the pickup, and also made a simple timing tab. The distance between each teeth is 6 degrees. |
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