Thread: harmonic balancer installation

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How do i know how far the harmonic balancer needs to go on the crank on a small block chevy 350. I think i have it in all the way but it has a bigger gap between the timing cover then the old balancer. i used a install tool and went to much i think cause i broke the tool.

I have broken several of those tools, they are not a good judge for the proper installation. When the harmonic balancer is seated all the way it will stop. If you want to lend yourself some comfort take a 2x4 lay it flat and smack it with a BIG hammer if its on all the way it will be like hitting a brick wall, if not the balancer will move. If it moves but the bolt on and tighten that way. Edd

OUCH!!! NEVER WHANG A HARMONIC BALANCER!!!!!

A harmonic balancer should not need whanging with a hammer/chunk of wood! Ever!! They are made of two pieces of forged iron or steel, depending on the make. These two pieces of metal are bonded together with an elastometric rubber like compound that is used to dampen internal engine vibrations which are caused each time a spark plug fires and ignites the fuel charge. It also helps dampen any imbalance in the engine from itself through the fly wheel or flex plate. Whanging with a hammer can damage, first of aall break the bond between the two pieces of metal, then the the thrust bearing - you have only about .001 to .002 clearance there, and with a new or rebuilt engine, little or no oil film to withstand heavy axial blows and can possibly chip ir otherwise damage the bearing surface.

The first thing to do before installing a harmonic damper is to make sure you have a clean snout, no raised metal from an inadvertent ding on the end. If you do, dress it with a fine file then strop it with some long strips of 220 then 400 wet and dry paper and some lubricant to remove any file marks. Once it is clean and smooth, a bit of anti sieze will help, though a thin film of oil will work as well. The balancer - you need to check the bore - as it too may have a ding that needs to be cleaned and the engine end radiused just a wee bit - that sharp edge may be digging in to the surface of the snout and causing your problem. That 220/400 grit here will help as well.

But, please don't whang a harmonic balancer with a hammer

i've always tapped it on about half way, then used the crank bolt to pull it home.

Use the proper tool. Not a hammer. The new one I just got for my Ls6 454
said it can be heated to 300 Deg in the over and then installed easier

First of all, to sand to fit is NOT what I said. I said file any dings on the crank snout, then use 220/400 to clean up any file marks.

Next, I said break the sharp corner on the inner side of the harmonic balancer to prevent digging into the snout thus making it harder (impossible??) to pull into place.

Pressing a balancer is NOT hammering it on.

I hope anyone that is pulling the balancer on with a bolt (Gr 8 or better!!) has enough sense to engage enough threads to prevent pull out - particularly if he has assembled the rest of the engine, he should then, I hope, have some basic mechanics skill level

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.

to each his own .. my favorite technique is to get undeployed airbags from local wrecking yards and stuff them between the radiator and the balancer then set them off .. poof !!!! on goes the balancer

Originally Posted by HOSS429

to each his own .. my favorite technique is to get undeployed airbags from local wrecking yards and stuff them between the radiator and the balancer then set them off .. poof !!!! on goes the balancer

Please take a video of this proceedure when you do it next time.
I was laughing very hard with that visual in my mind. Then I wondered how many readers would actually go and aquire an air bag ready for use and give it a go....I'd pay E ticket prices to witness that episode.

Har!! Yeah, I'd like to have a seat in the bleachers to watch that air bag trick.