As far as I can tell GM used 3 design harmonic balancer deigns:
2002
early 2003
late 2003 - end of production.
The 2002 balancer apparently is a dual mass design and lacks provision for the anti-spin washer.
Early 2003 design change went to a single mass design.
Some time during 2003 GM discovered that under certain conditions the balancer can spin on the crank snout (there is no keyway), the fix for this was to added a diamond coated washer to back of the balancer boss where it shoulders up against the lower timing gear.
The balancer is retained to the crank using a long 16mm grade 10.9 or better bolt. Its threaded deep into the crank - I believe into the area of #1 main bearing.
If the engine is on the engine stand you need 2 people to torque that bolt - 1 to stand on the engine stand and the other to turn the bolt.
Installation/removal procedure:
install the flexplate and size 10CR visegrips as tight as you can on the flex plate - rotate the crank until the visegrips bind against the block/engine stand. Lock the engine stand rotation.
torque the bolt to 110ft/#.
using a 3/4" flex handle and a 6" pipe over the flex handle continue tightening the bolt 180* - you will be grunting at the end its the mother of all bolts.
Aftermarket
Jeff Wiser commissioned BHJ to design a SFI balancer. Contact him to order. This balancer has a keyway and the crank needs to be modified to add the keyway.
This is a single mass balancer - but improved from the GM design - it extends the rpm range to 6400 from 6100.
Crank harmonics
GM tried twice to solve the crank harmonics which exist from 6400 to 7100/7200 rpm - avoid this operating region. For race engines accelerate through this rev range as fast as possible and ensure gear changes maintain the rpm following the shift above 7200.
Due to the light weight valve train the engine has no problems being spun hard if you take care of the valve springs, balancer oil system AND RUN A FULLY counter weighted crank
The black opel ran its 4200 as hard as 9300 one year - the sound was awesome.
Last edited by efi-diy; 12/09/18 09:00 PM.
