Topic: 6 3/4" vs. 8" balancer
in Forum: C3 Engines
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Lifetime MemberManteca, CA - USA
Joined: 11/20/2005
Posts: 3623
Vette(s): 1978,two tone,Metalic Rootbeer & gold
1975 L48 4 speed
Anybody in the mood to give us the benefit of their knowledge on the pros and cons of larger or smaller balancers. I've got both sizes on my 350s. The weight difference is obvious but will opting for the 6 3/4" for quicker RPMs shorten the life of the motor due to increased harmonic vibration?
Jimmy B.
Just can't wait to get on the road again. 
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Oak Creek, WI - USA
Joined: 5/21/2008
Posts: 1965
Vette(s): 1981 Great White Shark. Red Interior, 350/190 hp. PS, PB (SS), A/C CC, T-Tops. Served three years in Active Duty Army, then Retired Air Force after 34 years! Badger State Vettes Car Club. 175,000 Original miles!! Now own a 1998 C-5!
Well, my manual calls for the 8" on my 81. It was designed for an 8" and I'm stickin with that. I am feeling some vibrations so it is time to replace the harmonic balancer.
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Mounds View, MN - USA
Joined: 5/24/2007
Posts: 1031
Vette(s): 70 LT1 coupe, 69 350 HP coupe, 69 390HP 427 coupe, 71 LS5 convert, 85 coupe, 93 coupe
The whole rotating assembly is balanced as a unit, so as long as you send the smaller harmonic dampener to the balancing service, it won't affect engine life significantly. You are correct that a smaller, lighter balancer will, at least in theory, allow the engine to rev faster.
Larry
Larry
Lifetime MemberManteca, CA - USA
Joined: 11/20/2005
Posts: 3623
Vette(s): 1978,two tone,Metalic Rootbeer & gold
1975 L48 4 speed
Thank you Larry. I appreciate your imput. It's confusing when one performance engine builder states that they use the 6 3/4" exclusively for small block Chevy motors and yet GM mounts an 8" on their ZZ4.
Jimmy B.
Just can't wait to get on the road again.
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Mounds View, MN - USA
Joined: 5/24/2007
Posts: 1031
Vette(s): 70 LT1 coupe, 69 350 HP coupe, 69 390HP 427 coupe, 71 LS5 convert, 85 coupe, 93 coupe
The ZZ4 is a high torque engine (for a small block), so it makes sense to use a bigger one. They seem to have gone to the big ones on all small blocks for years.
Larry
Larry
in Forum: C3 Engines
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