401 harmonic balancer

Purple77CJ7

Hi all new here. I went to replace the harmonic balancer because rubber was cracked and falling out. Ordered an aftermarket balancer and went to install it and found out the original balancer was for a 304 not the one for a 401. Set up the new one with the weight for 401 and the weight hits the timing cover. So set up for the 304 weight. My question is am I going to cause damage. I have been running it with the 304 balancer for 10 years and about 30000 miles. I don't know if PO just slapped that one on or if crank was balanced for it. My son says if it ain't broke just leave it. Your thoughts? Dennis

tufcj

AMC V-8s are externally balanced. The harmonic and flywheel are part of the balance of the engine and are displacement specific. That's not to say that the engine couldn't have been balanced with a 304 harmonic, but if it wasn't, the vibration will cause premature wear on the main bearings, and cause a noticeable vibration at higher RPM.

What brand is the aftermarket harmonic? I have heard of fitment problems with some of the aftermarket ones?

My suggestion would be to find a good used OEM 401 balancer. If you can find one that needs a rebuild for cheap, I'd recommend www.damperdoctor.com

Bob
tufcj

Purple77CJ7

The balance I installed is a Powerforce. I don't have any unusual vibration, I did put anew set of rod and main bearing in from the bottom. Main bearings were wore but not excessive. I don't know how many miles are on the engine since it was rebuilt by PO. Thanks!

Purple77CJ7

I tried to get in touch with Professional Products who make Powerforce dampers, about fitment, no response. Bought a replacement stock damper from Damper Doctor. Thanks tufcj.