Thread: VERY small SBC Harmonic balancer/pulley troubles

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Hey Dave –

Well there’s some bad news and some good news. First the bad news – your stock harmonic balancer (really a “harmonic dampener” as the 4.3 V6 is internally balanced) will not accommodate aftermarket pulleys. The stock unit has a lip around the edge that will prevent a true alignment. (See the pictures below). Even though the bolt pattern is the same as a V-8 and everything will “tighten up”, the lip will cause this mis-alignment you’re experiencing.

The good news is that there are some aftermarket dampeners that will work well with your application, specifically, a unit from Pioneer (PN 872021) a 6.125-inch, unit that fits perfectly. In that the 4.3 is an internally balanced engine like a 350 you’ll be fine with this unit. They’re available for about $150. Check out this link to Summit:

http://www.summitracing.com/parts/PIO-872021/

I’m glad to see you using this engine. It’s a great unit and often overlooked because it’s a “six banger”. The bore centers are 4.400”, the deck height is 9.025” which is identical to a 350. The 1985 and newer 4.3 has the same bore and stroke as a 350 V-8 (4.000” x 3.480”), and uses the same pistons, cam and main bearings, valve train components, timing cover, oil pump, and water pump. Connecting rods are 5.700 inches like a 350, but the journal size is 2.250” rather than the 350’s 2.100” so they are not interchangeable.

The 4.3 can be lethal when built correctly.

Regards,
Glenn