sbc harmonic balancer

Dave Casey · 03-02-2013, 06:53 PM

I believe that the balancer that I used on my 305 stocker for years is the one you are refering to. It worked fine for me for 20 years, it is a narrow balancer. It would probably still be on my car, but I believe g/s and faster requires an aftermarket balancer and I put one on.

I always assumed that the rear of a one piece seal 305/350 crank is balanced externally, but the front was not. Is that correct ?

Rob Petrie E395 · 03-02-2013, 07:19 PM

Did I screw up when I ordred my Damper? ATI has several available for my engine (Late Model LT1) My thought was the less weight on the crank the better for performance. So instead of getting the 7.53 inch steel one I got the 6.78 inch Aluminum one. The steel one weighs 9.75 Lbs. the one I got weighs 4.5. I figured that much weight had to be worth something in terms of performance. Should send it back and get the steel one? Or is the Alum ATI super damper as good as the heaver steel one they sell? Thanks

Alan Roehrich · 03-02-2013, 08:07 PM

Rob, I run the lightest aluminum damper ATI makes on my big blocks, you'll be fine.

It isn't the aluminum that makes those old hubs bad, it's the fact that they are not dampers at all, but rather just a hub to bolt a pulley on, and stop the front cover from leaking.

Adger Smith · 03-02-2013, 09:22 PM

Correct Dave.
The flywheel on the one piece crank is smaller on the hub and has a smaller bolt circle it also has what is called a "Butterfly weight"
That weight replaces the "Ear" that is on most 2 piece seal cranks out side the seal surface. That ear is usually weight that is in line with the rear counterweight. The ear is cut off on the 1 piece cranks. They are full round in that area.
The balancer end of the crank is neutral balanced.
Rob the small is OK

Rob Petrie E395 · 03-02-2013, 10:14 PM

Thanks guys. While this engine will not by any means be the fastest one out there. I dont need to tear it up with a foolish mistake. Thanks again

03-02-2013, 06:53 PM	#1
Dave Casey VIP Member Join Date: Dec 2002 Location: Hampden, MA Posts: 1,202 Likes: 233 Liked 797 Times in 165 Posts	Re: sbc harmonic balancer I believe that the balancer that I used on my 305 stocker for years is the one you are refering to. It worked fine for me for 20 years, it is a narrow balancer. It would probably still be on my car, but I believe g/s and faster requires an aftermarket balancer and I put one on. I always assumed that the rear of a one piece seal 305/350 crank is balanced externally, but the front was not. Is that correct ? __________________ Dave Casey 1330 STK

03-02-2013, 07:19 PM	#2
Rob Petrie E395 VIP Member Join Date: Dec 2007 Location: Woodlawn IL Posts: 1,092 Likes: 162 Liked 216 Times in 77 Posts	Re: sbc harmonic balancer Did I screw up when I ordred my Damper? ATI has several available for my engine (Late Model LT1) My thought was the less weight on the crank the better for performance. So instead of getting the 7.53 inch steel one I got the 6.78 inch Aluminum one. The steel one weighs 9.75 Lbs. the one I got weighs 4.5. I figured that much weight had to be worth something in terms of performance. Should send it back and get the steel one? Or is the Alum ATI super damper as good as the heaver steel one they sell? Thanks

03-02-2013, 08:07 PM	#3
Alan Roehrich Veteran Member Join Date: May 2006 Location: Murfreesboro TN Posts: 5,126 Likes: 1,583 Liked 1,892 Times in 423 Posts	Re: sbc harmonic balancer Rob, I run the lightest aluminum damper ATI makes on my big blocks, you'll be fine. It isn't the aluminum that makes those old hubs bad, it's the fact that they are not dampers at all, but rather just a hub to bolt a pulley on, and stop the front cover from leaking. __________________ Alan Roehrich 212A G/S

03-02-2013, 09:22 PM	#4
Adger Smith VIP Member Join Date: Dec 2001 Location: Texarkana Ark/TX Posts: 2,446 Likes: 575 Liked 880 Times in 311 Posts	Re: sbc harmonic balancer Correct Dave. The flywheel on the one piece crank is smaller on the hub and has a smaller bolt circle it also has what is called a "Butterfly weight" That weight replaces the "Ear" that is on most 2 piece seal cranks out side the seal surface. That ear is usually weight that is in line with the rear counterweight. The ear is cut off on the 1 piece cranks. They are full round in that area. The balancer end of the crank is neutral balanced. Rob the small is OK __________________ Adger Smith (Former SS)

03-02-2013, 10:14 PM	#5
Rob Petrie E395 VIP Member Join Date: Dec 2007 Location: Woodlawn IL Posts: 1,092 Likes: 162 Liked 216 Times in 77 Posts	Re: sbc harmonic balancer Thanks guys. While this engine will not by any means be the fastest one out there. I dont need to tear it up with a foolish mistake. Thanks again