Thread: harmonic balancer installation

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I don’t know about other than SBC, but I do know that the correct way to install a harmonic damper on a SBC is to coat the crank snout and the inside of the harmonic balancer with anti-seize compound and press the damper into place with a proper installation tool.

Some people think that the woodruff key is supposed to keep the harmonic damper in place on the crankshaft snout. This is not the case as it is much to small to take the stress imposed by a crank turning at thousands of RPMS that is being hammered by multiple explosions. The key’s only purpose is to position the damper correctly during installation - it is the press fit between the damper inside diameter (ID) and crankshaft outside diameter (OD) and a grade 8 bolt properly torqued, that prevents the damper from spinning on the crank. The ID of a damper should not be honed nor the crank snout relieved to provide a slide on fit. [I concur with IC2 on light dressing of nicks and burrs] If a tight fit is not achieved, a damper's effectiveness is minimized because it does not maintain firm contact with the crankshaft and even a slight wobble can be disastrous.

I have one similar to this, at NAPA for about $45-50. It's worth it if you're going to build more than a few motors. Most NAPA store will rent one for less than ten bucks.

Measure the crank snout with a micrometer, (if you don't have one the local machine shop may lend you one) then have the above mentioned local machine shop measure the inside diameter of the balancer.

Now have the machine shop machine the balancer for .001 to .0014 fit.

NO HAMMER.

True, hammering doesn't damage the crank, but it raises hell with the htrust bearing.

Why is ther never enough (time or money) to do it right, but always enough to do it over???????????????????????

Originally Posted by DennyW

Example:
I'm sitting at a light, I have a stick trans. A guy pulls up, and wants to race. I up the rpm's, cause the light is about to change. 5 grand, and I'm off the clutch...what impact does this have on the thrust bearing ?? Way more than a hammer.

I'm cruising down the highway, and decide to do some gear jamming...I downshift right at the limit of the next gear. Very quickly, so it slows me down fast...What impact does that have on the other side of the thrust bearing ?? Way more than a hammer in the opposite direction.

Denny - that is not true. You have a lot more potential to damage a thrust with the engine not running then dropping the clutch. You are running xx pounds of oil pressure and it is flooding the bearings with lube oil while it is running, therefore maintaining a cushion. If you are hammering a harmonic balancer on, it might have some residual oil but not a warm continual flow at xx psig. If it's a new build, again, you might have some residual oil or maybe even some assembly lube, but most folks don't use anything but what ever oil they use for break in or operation to put a set of mains or rod inserts in

I am not a fan of the hammer, regardless of what I may espouse in my grumping and growling. However, there is a precedent for using a hammer and wood block to install the balancer/dampener on a small block Chevy: on the early engines, 265, 283, and early 327, in times before the crank was drilled and tapped, the factory manual laid it out something to the effect that you line the keyway up and tap the hub until the key is started in the balancer slot, then using a block of hardwood, and a "lead" mallet, drive the balancer to seat. You could tell when it was seated by the sound it made when struck: when it had a solid, sort of ringing sound, rather than having a dead, "thunk" sound, it was in it's proper place. In the later incarnations of the mouse, the re-engineering might have been because of concerns over the forces applied in driving the balancer on, and the differences in later casting techniques and designs using lighter or thinner webs in the crankcase; in the older casting designs, the webs were thick and undoubtedly quite strong, and could probably better withstand the forces of the pounding. At least, that's my take on it. I do have an installing tool, a good one, with bearings and bushings and different studs, and prefer to use it; but when faced with an older engine, like that '59 283 I have, I will used the hammer and block, if that's what is needed.

Originally Posted by Rrumbler

I am not a fan of the hammer, regardless of what I may espouse in my grumping and growling. However, there is a precedent for using a hammer and wood block to install the balancer/dampener on a small block Chevy: on the early engines, 265, 283, and early 327, in times before the crank was drilled and tapped, the factory manual laid it out something to the effect that you line the keyway up and tap the hub until the key is started in the balancer slot, then using a block of hardwood, and a "lead" mallet, drive the balancer to seat. You could tell when it was seated by the sound it made when struck: when it had a solid, sort of ringing sound, rather than having a dead, "thunk" sound, it was in it's proper place. In the later incarnations of the mouse, the re-engineering might have been because of concerns over the forces applied in driving the balancer on, and the differences in later casting techniques and designs using lighter or thinner webs in the crankcase; in the older casting designs, the webs were thick and undoubtedly quite strong, and could probably better withstand the forces of the pounding. At least, that's my take on it. I do have an installing tool, a good one, with bearings and bushings and different studs, and prefer to use it; but when faced with an older engine, like that '59 283 I have, I will used the hammer and block, if that's what is needed.

That pretty much sums it up and should end the discussion, but then us "old farts" who worked on early sbc's were quite aware of the procedure.