L79 Harmonic Balancer

[Daniel O.]

I have a small block 327 L79 engine with forged crankshaft part # 383849 id#2680. I would like to know the correct Harmonic Balancer to use. The crank has a non-threaded end. The "reinforced ribs'' 327 w/sp hp has an attaching bolt & washer. Thanks Dan

[Joe L.]

Re: L79 Harmonic Balancer

I have a small block 327 L79 engine with forged crankshaft part # 383849 id#2680. I would like to know the correct Harmonic Balancer to use. The crank has a non-threaded end. The "reinforced ribs'' 327 w/sp hp has an attaching bolt & washer. Thanks Dan

Dan------


I do not understand why your crankshaft does not have a snout threaded for a balancer bolt. It should have. The balancer used with all 1962-68 Corvettes with SHP (which includes 1967 L-79) was GM #3817173. However, this balancer is used with a retaining bolt of GM #3815933.

[Mike M.]

Re: L79 Harmonic Balancer

passenger car and corvette sbc's with hydraulic lifters the likely source of your non-threaded crankshaft snout. its rather easy to drill and tap your crank for the harmonic balancer retaining bolt. i believe they are 7/16" fine thread bolts. i just recently had to drill and tap my non-solid lifter crank in a L-84 i rebuilt. original crank was scraped.BTW, the non-tapped crankshaft i did recently already had a pilot hole started in the crank, making centering the drill bit rather easy. mike

[Joe L.]

Re: L79 Harmonic Balancer

I have a small block 327 L79 engine with forged crankshaft part # 383849 id#2680. I would like to know the correct Harmonic Balancer to use. The crank has a non-threaded end. The "reinforced ribs'' 327 w/sp hp has an attaching bolt & washer. Thanks Dan

Dan------

One more thing: are you sure the engine is an original L-79? It's pretty easy to make a 300 HP appear pretty much like an L-79. Change the intake manifold, valve covers, harmonic balancer and pulley system and one is pretty much there as far as external configuration goes. In this case, maybe they didn't get the harmonic balancer and pulley system changed.

By the way, all 1962-67 327's were equipped with a forged crankshaft.

[Joe R.]

Re: L79 Harmonic Balancer

passenger car and corvette sbc's with hydraulic lifters the likely source of your non-threaded crankshaft snout. its rather easy to drill and tap your crank for the harmonic balancer retaining bolt. i believe they are 7/16" fine thread bolts. i just recently had to drill and tap my non-solid lifter crank in a L-84 i rebuilt. original crank was scraped.BTW, the non-tapped crankshaft i did recently already had a pilot hole started in the crank, making centering the drill bit rather easy. mike

Just to be clear for the OP, the crankshaft hole CAN be drilled and tapped with the engine in the car, provided you remove the fan to give yourself some maneuvering room. To help keep the drill straight and centered, I removed the balancer and made a simple guide fixture that slips over the snout of the crank.

To my knowledge, all L79 engines had the threaded hole in the crank snout, so if the OP's crank does not have that hole, the crank is probably not an original L79 crank. Maybe it's a replacement crank.

Also, as Joe Lucia has pointed out, lots of 300 HP engines have been "dressed" by previous owners to look like an L79. One thing that most of these conversions do not change is the balancer/damper and the timing cover. The L79 used a larger balance/damper and a different timing cover.

[Barry H.]

Re: L79 Harmonic Balancer

Joe, Wasn't the #3817173 an 8" damper with the "internal fins"?
Barry Holmes

[Joe L.]

Re: L79 Harmonic Balancer

Joe, Wasn't the #3817173 an 8" damper with the "internal fins"?
Barry Holmes

Barry-----


Well, it was an 8" balancer but not all of them had the fins. Some folks think that the fins only disappeared on later SERVICE examples. That's not how it was, though. The fins were deleted sometime during the 1967 model year, perhaps even at the beginning of the year.

[Leif A.]

Re: L79 Harmonic Balancer

Barry-----


Well, it was an 8" balancer but not all of them had the fins. Some folks think that the fins only disappeared on later SERVICE examples. That's not how it was, though. The fins were deleted sometime during the 1967 model year, perhaps even at the beginning of the year.

My June '67 build, original L79 does not have the fins on the engine side of the balancer.