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-   -   sbc harmonic balancer. need guidance. (http://www.hotrodders.com/forum/sbc-harmonic-balancer-need-guidance-232511.html)

dusterbd 05-03-2013 08:54 PM

sbc harmonic balancer. need guidance.
 
ok, so ive got a 73 vintage 350 in my project. codes came back as a truck motor with a 3 speed behind it.
at some point it was freshened. unknown to what extent. runs good, sounds good, checks out healthy. pretty strong, too.

anyway, i converted it to serpentine accessories. in the process, i discovered that the harmonic balancer has 3 nubs sticking out in addition to the three pully bolt holes. ive never seen this. nor does any of the aftermarket pullies support this. all of them only have the 3 bolt holes. i drilled my serpentine crank pully to account for them, but it now does not run true. dont know why. planning on clearancing the holes a little more, and seeing if i can get it to self align.

makes me wonder just what the balancer is off of.
also, makes me wonder if i can grind those nubs off. make it so i can run an unmodified pully.
what do you small block guys say? im kind of baffled here.

michael

68NovaSS 05-04-2013 12:49 AM

What's the damper off of? Can you put up a picture of these 'nubs'?

ssmonty 05-04-2013 01:48 PM

1 Attachment(s)
Does your pulley have the typical lip that locates it to the center of the dampner?
Does your pulley wobble up & down like its not centered, or wobble back & forth like one or more of the "nubs" is keeping it from mating flush with the face of the dampner?
ssmonty

dusterbd 05-04-2013 07:23 PM

it does have the lip. bu7t suprisingly, no crank bolt was in the engine.
it wobbles up and down. i drilled some roughly 1/2 inch holes based off the old v-belt pully to clear the "nubs"
pics will be difficult, as the truck is currently outside in the gravel so i can work on a friends 68 firebird, a 69 442, and a 70 duster. so im trying to fix it (it IS my truck after all...) in the gravel on my back before the not running true eats a front crank bearing. id assume that the wobble would be enough to misbalance things and wear bearings pretty quick.

michael

dusterbd 05-04-2013 07:31 PM

best pictures i have. forst pic you can kind of see the nubs on the harmonic balancer.
second pic is of the v-belt pulley i removed with the nub holes, and the non holed serpentine pully matched together.
http://i54.photobucket.com/albums/g1...ps75ef2dc3.jpg
http://i54.photobucket.com/albums/g1...ps9818afa3.jpg

techinspector1 05-05-2013 12:43 AM

It has been a long time, but I think those nubs are rivets that held the belt pulley to the damper on some early 265 and 283 motors. Take a look.....
Damper Doctor Online: CHEVY 265/283 C.I.

ssmonty 05-05-2013 07:04 AM

I think wobbling up and down would indicate its not centered. Does the serpentine pulley move around some when you place it on the dampner and try to slide it around, or does the lip snap in the hole?
If its moving around, you might be able to make a shim of sorts to center it by laying a 2 foot length of masking tape on something like a glass table that's clean so that when you remove the tape it doesn't tear or pick up dirt. Then use an xacto or box knife to cut a long thin strip(sort of like pin stripping) about an 1/8" wide. After cleaning the dampner hole, and the pulley lip with alcohol, wrap the strip around the pulley lip a few times until its just larger in diameter than the hole in the dampner. Then try to lay the pulley on the dampner with light pressure as you unwrap/cut some of the tape a little at a time until it just fits if you know what I mean. It won't center it perfectly as you'll have more layers of tape on one side vrs the other, but it might get it close enough. I think masking tape is about .004" thick. It will probably take some trial and error.
Just a thought. FWIW,
ssmonty

dusterbd 05-05-2013 11:27 AM

i think im going to try another pully first, and then try the shims. by what i can see, its not getting hung on the nubs.
the whole pulley is actually moving in an elliptical when the engine is running. in/out is fine, but its not true to the crank. the center of the pulley and the center of the crank snout sont seem to line up. so im wondering if my pulley ,may have gotten bent somehow. this crank pulley was given to me by my machinist, so it may have been in an accident or something. dont know.
i also bought a crank bolt, because my engine does not currently have one.

would it be OK to grind those nubs off, or would that throw things out of balance potentially?

thanks
michael

ericnova72 05-05-2013 01:41 PM

I'd get a different balancer if it was me, one from a later engine (1960's-mid70's). The one you have is one of the worst as far as dampening ability, because it is so small. You have an ancient relic from the early 265 or 283 cube engines, as the TechInspector guessed. All later balancers on larger and more powerful small blocks were a lot thicker in the outside weight, which makes them more effective at canceling vibrations, where yours is just a thin ring. It was only used on early and low performance applications.

You will have a hard time getting a pulley to run true, unless you can find the early (1950's era)CAST IRON pulley that goes with that balancer.

The later pulleys and dampeners have a centering lip on the pulley the fits just into the crankshaft opening of the balancer snugly.

ssmonty 05-05-2013 02:23 PM

Before you buy a crank bolt you had better make sure that crank actually has a tapped hole. The earlier engines didn't.
It may also make a difference as to whether or not you want to install a new dampner. Kind of tough on the thrust bearing if you have to beat the dampner on with a sledgehammer instead of buying or borrowing a tool(Autozone has loners) that threads into the crank hole specifically designed for the job(in case you didn't know).
ssmonty

techinspector1 05-05-2013 02:42 PM

Quote:

Originally Posted by ssmonty (Post 1673130)
Before you buy a crank bolt you had better make sure that crank actually has a tapped hole. The earlier engines didn't.
It may also make a difference as to whether or not you want to install a new dampner. Kind of tough on the thrust bearing if you have to beat the dampner on with a sledgehammer instead of buying or borrowing a tool(Autozone has loners) that threads into the crank hole specifically designed for the job(in case you didn't know).
ssmonty

Or you can put the damper in the oven at 200 degrees for a half hour and pack the crank snout with ice for a half hour. The damper will slide right on. Remember to handle the damper with oven mitts.

oldbogie 05-06-2013 01:23 PM

Quote:

Originally Posted by dusterbd (Post 1672618)
ok, so ive got a 73 vintage 350 in my project. codes came back as a truck motor with a 3 speed behind it.
at some point it was freshened. unknown to what extent. runs good, sounds good, checks out healthy. pretty strong, too.

anyway, i converted it to serpentine accessories. in the process, i discovered that the harmonic balancer has 3 nubs sticking out in addition to the three pully bolt holes. ive never seen this. nor does any of the aftermarket pullies support this. all of them only have the 3 bolt holes. i drilled my serpentine crank pully to account for them, but it now does not run true. dont know why. planning on clearancing the holes a little more, and seeing if i can get it to self align.

makes me wonder just what the balancer is off of.
also, makes me wonder if i can grind those nubs off. make it so i can run an unmodified pully.
what do you small block guys say? im kind of baffled here.

michael

Wow an old one, Chevy just used a pressed on damper years ago except on performance engines. There is a kit that most decent parts stores stock that has a 7/16ths x20 x1.5 inches bolt a thick washer and sometimes the correct tap to thread the tooling hole in the crank's snout. Good insurance. The nubs on the back of the pulley are there just to hold it aligned to the damper. Older dampers don't have the mating feature, so newer pulley's can have this ground off, or the old damper counter-bored to accept them.

Frankly, I'm not that enamored with serpentine belts that I would've spent good money that can be used to better purpose elsewhere than to play around with the accessory drive.

Bogie

techinspector1 05-06-2013 02:07 PM

I agree. To me, it's much ado about nothing.

dusterbd 05-06-2013 07:33 PM

the serpentine accessories were the cheapest, easiest way to get where i wanted to be: late model alt, power steering, AC, and new water pump. all told ive got 60 bucks in it.

i think, whats going to happen with the damper problem, is that im going to give it to my dad whos building a correct 283 for his 60 vette, and just get a new balancer, bolt, etc and be done with it.

by the way, its a soon to be daily driven 64 el camino that im building.

michael


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