Jvette73

The outer ring on my 73 350 has slipped all the way back and is rubbing on the timing cover. Wheres the best place to get a new one. I notcied an oem model in the summit catalog for $60. It notes that this oem replacement is not intended for "extended" use beyond 4500rpm. Im not above that point all the time, but I do spend my fair share of time revving to 5500rpm thru the gears. So will this stock replacement be sufficient, or should I go to a more expensive performance part?

Scott78

OEM should be OK. But I'd anty up the few extra bucks for the "Streetdampr" for piece of mind.
Scott

A C

I would go with the streetdamper or another good damper. It will save you money in the long run, IMO.

AC

Fevre

The summit one is as good or better than OEM and that one lasted how long? If you don't go above 4500 rpm's for extented save the $ and go the summit route, I did.

Tom454

Heads up...

They fail for a few different reasons, but one very common reason is because Bubba installed it by pounding it on with a hammer.

Purchase, rent, or borrow a harmonic balancer removal/installation tool for the job. Do not pound on a harmonic balancer to install it.

PatsLs1vette

Ive been using stock ones on my circle track motors for 3 years and just this week it went outter ring slipped off.Now thats 6500-6800 rpm for laps upon laps for 3 years ..so youll be fine with an oem from summit,we just ordered the same one to replace it.(our rules only allow oem balancers no fluidampner in this class.)

Jvette73

Im pretty sure when I got the car the the harmonic had never been pulled. When I went to install the comp cam I found a very tired, brittle, and cracking nylon toothed cam gear. So I was the first to remove and install it. I "did not" use a puller that pulls on the outer ring. Puller attached to the 3 pully bolt holes and pulled fron the center section. On re-installation I did not use a tool. Ive always used this method with no problems. I place the harmonic in posistion on the crank. I set aside the thick crank washer and opt for a thinner one to allow more thread reach of the bolt into the crank threads. Then, I cut a small piece of 2x4 to hold across the harmonic and gentaly tap the pully on just far enough to get enough portion of the crank bolt threads into the crank. Then I begin to use the crank bolt itself to draw the harmonic on about half way. Then I remove the crank bolt and replace the thin washer with the original thick one and draw it the home and tq. I use enginuity when I can. At this point in my hobbiest level automotive adventure I rarely resort to total bubba such as whailing in the end of the crank with a hammer so to speak. I remember it being a smooth process but none the less I suppose its possible I could have caused the problem. Possible but not probable.

Heres a Q on the subject as well. I have the large 8" harmonic. So is it important that I get the same diameter balancer to replace it? If so will this limit my choices? I noticied the in the catalogs the only 8" balancers available are in the oem catagory.

Pete79L82

6 3/4" and 8" balancers are interchangable as long as you use the correct timing pointer with them so you can time the motor properly. The OEM balancers are fine. The rest are just sales gimicks. I use a stock OEM balancer (6272221) on all my race motors and they run for years at 8000 RPM on a circle track.

72rdstr

I've done exactly this a number of times; always waiting for that one time I didn't beat the odds. Looks like you gambled and lost on this one. The age and brittleness of the rubber probably contributed. :yesnod:
OEM will work fine. Rent an installer? Even I would in your case just to avoid the wife ever finding out it was my fault. :blueangel:
Good luck

Jvette73

Opps...I just realized that I have the 6 3/4" diameter balancer. Have to send back the 8" one. Now Im back to the choice. Streetdamper for $150 or oem for $65. With the oem I will need to add timing tape so that adds another $6 to the figure. Does anyone know if the Streetdamper has the timing scale already marked on it? It didnt list so in the catalog and the picture wasnt clear enough to determine. I kinda like the idea of the Streetdamper. Im leanin that way. Also, I went to the hardware store and got a grade 8 bolt that was the same size as the crankshaft bolt except 1/2" longer. Now I can use it in conjunction with a thinner washer to begin with to draw the balancer on without ever needing to strike it, even if gentally. I will use the longer bolt to draw it on half way or so, and then switch back to the original bolt and washer for the final draw and tq. Cost of longer crank bolt--$1.77. Thanks to everyone for all the help in this matter. Dis-assembly went without a hitch.

Gator81

Same thing happened to me. Replaced with stock GM unit, about $45 over the counter at the Chevy dealer. :cool:

robzr

I'm with Pete on this one. I read a paper by either Cola or Scat regarding crankshafts, alloys, balancers, etc. They mentioned a bit about harmonic balancers that they had learned (partly from analysis of returned/broken cranks). BTW, it mentioned that they can usually determine the reason why a crankshaft has failed over a phone conversation, they have it down to such a science that actual physical analysis is rarely needed. Anyways, the paper stated that a fluid type dampner may be detrimental for a motor which sees a lot of changes in RPM range. Ie; a drag racer, whose motor quicklky revs through the power range. Fluid based dampners may be better for higher RPM motors which do not constantly see quick RPM changes - like road race or circle track. At any rate, they didn't seem to be big fans of them. I think it's a marketing thing. Look at all the motors which have seen hundreds of thousands of miles without them; if the concept was really valuable, you'd think the LS1 would have them, or other high revving motors like the Honda S2Ks powerplant. You are probably best off buying a quality solid dampner and saving the money. I've never heard anyone "in the know" recommend them, either.

Rob