Harmonic balancer

[Clone TIE Pilot]

I suspect the harmonic balancer on my Chevy 305 maybe going bad or has slipped. I noticed the outer ring is almost touching the timing cover, almost a paper thin gap. Looking under the car, I can see the inner hub and rubber ring stick out forward from the outer ring. Heard that when balancers slip, the outer ring can migrate inboard towards the timing cover. The rubber ring does not appear to be sheered or separated though it does have a couple of cracks and looks worn and beat up. As far as I know it is the original balancer to the engine which has 100k on it.

 

[Longroof79]

Sounds like it may be time to consider a replacement. Get a good aftermarket replacement with the timing degree scale etched on.
They are known to degrade over time.

 

[Clone TIE Pilot]

Sadly it looks like GM has discontinued the part.🙁 Guess will have to find a aftermarket one.

 

[565bbchevy]

There are plenty of affordable aftermarket ones for sbc and the hubs and outer rings are typically machined pretty nice along with elastomer technology has most likely improved over the last 30 years.

 

[pontiacgp]

in case your are not aware when you are changing the balancer if you need to change the timing cover seal don't try to install the seal with the timing cover still installed. It's easy to damage the cover trying to drive the seal in.

 

[Clone TIE Pilot]

Rockauto lists two brands of 6.75 balancers for Monte Carlos. One is Dorman and the other is Dayco.

 

[Clone TIE Pilot]

Also found a place called Damper Doctor that sells rebuilt OEM dampers as well as rebuilding your original damper. OEM dampers tend to have better machining than aftermarket units. 305s use a 12:00 tdc mark while 350s use 2:00 tdc and it seems most aftermarket dampers are 2:00 tdc.

 

[pontiacgp]

you need to get a balancer for a 305, if you use one from a 350 you can make your own mark on the balancer at 12:00. As far as aftermarket I have one and found it to be made very well and with the timing marks on the balancer I could adjust the valve lash on my roller lifters.

 

[Clone TIE Pilot]

I mainly meant aftermarket stock replacements tend to have the crank snout hole machined oversize, especially Chinese dampers. Concerned if either the Dorman or Dayco dampers would be ok or if I should get a rebuilt OEM? Supposedly 305s and 350s have different harmonics and they are clocked differently to help prevent people from mismatching their dampers. I probably do not need a race rated damper and they probably all are setup for 350s.

Edit, found several reports that the cheap Dorman dampers are loose fits that can push on by hand, not the proper press tight fit.

 

[Clone TIE Pilot]

Also see that many of the aftermarket damper covers have dual TDC marks, a fancy 2:00 marks ( 10 degrees before keyway) with several printed degrees, and a plain 12:00 mark (40 degrees before keyway). Think it would be a good idea to use a cover on whatever damper I get?