Hamonic balancer Interference Fit
Thread Starter
Intermediate
Joined: May 2007
Posts: 48
Likes: 2
From: Reading PA
Hamonic balancer Interference Fit
I'm finishing up the engine build on my 73 L48. I'm using a cast SCAT crank with a balancer snout diameter of 1.236. My new GM balancer has an ID of 1.225. 11 thousandths seems like a very large interference fit to overcome when installing the balancer. Thoughts? Anybody know what the correct interference should be?
Thanks,
Dean
Thanks,
Dean
Melting Slicks
Joined: Feb 2006
Posts: 3,428
Likes: 5
From: Japan
Have you verified these dimensions by measuring them? That seems a little wierd- I'd suspect a typo somewhere. Actual interference should be closer to .001". If you actually tried to install it with that much interference you'd strip out the threads on your crank pretty quickly....
Thread Starter
Intermediate
Joined: May 2007
Posts: 48
Likes: 2
From: Reading PA
I've measured both with a digital vernier caliper. Readings were consistent when taken at 120 degree intervals around the circumference of both pieces. i did find something interesting. on about ther first 3/8 inch of the balancer (engine side) it has been machined to about 1.235. This part slides on to the crank with a little effort.
Burning Brakes
Joined: Oct 2006
Posts: 1,006
Likes: 28
From: Lutz Florida
They may tell you that you will have to hone the balancer a bit to enlarge the ID in order to install it. I installed an ATI Super Damper balancer on my stock l-48 crank snout and had to hone the damper slightly to open the ID up, and then use anti-seize as the lubricant on the crank snout, to install the balancer. The tolerances were in the installation instructions.The specs will most probably be different for your combination than mine were, but you may need to do a little machining in order to install your balancer.
Intermediate
Joined: Jul 2008
Posts: 41
Likes: 0
From: Raleigh NC
They may tell you that you will have to hone the balancer a bit to enlarge the ID in order to install it. I installed an ATI Super Damper balancer on my stock l-48 crank snout and had to hone the damper slightly to open the ID up, and then use anti-seize as the lubricant on the crank snout, to install the balancer. The tolerances were in the installation instructions.The specs will most probably be different for your combination than mine were, but you may need to do a little machining in order to install your balancer.
I purchased a stone brake hone from advance auto, attached it to my cordless drill with some oil. Took basically just the paint off the balancer and went on smoothly.
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
I doubt you will get satisfactory ( accurate ) results with calipers, that is not the way to measure these components. Does the balancer go on with some resistance like it is supposed too ? 
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Safety Car
Joined: Oct 2004
Posts: 3,922
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From: Youngstown Ohio
The interference fit should be closer to .005 or slightly less. If it starts to go on (tightly) but you're starting to get nervous, I've had success by removing it and heating it in hot (but not boiling) water, then quickly out of the water, apply some oil then install it. It will go on easier.
