[johns79z28]

Can someone help me with a question about balancer size?
I am putting my engine back together after a long illness and
need to know the importance of using different sizes.This
is a SBC 350 4v turbo 400.It is a 350 2 bolt block with new
.020 forged pistons,new 270h cam ,pete jackson gear drive
aluminum heads,roller rockers ,studs and plates not an all out
engine but much more than stock.Will be put back in my 79 Z-28
no smog.I do have a 6 3/4 and an 8" and am not sure what would
be better or if it would matter.Thanks
John

 

[Henry Highrise]

It should not matter if they are both for internal balance engines ( the 400 sbc used external balance). I like the smaller size myself.

 

[johns79z28]

Thank you for the reply.I will use the smaller one since it
is sfi certified. John

 

[fast68]

87-up were external again, 305 and such engines

i personalyl prefer 8" balancers, most of the 4bbl 350 engines were 8"

and some werent, and were instead fitted with the widest balancer, identical in appearance to the 305 ones, 6 and 3/4 OD



good luck

 

[jimfulco]

The 8" dampers reputedly tame torsional vibration better than the smaller ones, so cam timing stays more stable, yielding better power.

 

[CNC BLOCKS NE]

87-up were external again, 305 and such engines

i personalyl prefer 8" balancers, most of the 4bbl 350 engines were 8"

and some werent, and were instead fitted with the widest balancer, identical in appearance to the 305 ones, 6 and 3/4 OD



good luck

Thats 86 up and they are external on the rear and neutral on the front.

And using a gear drive it may be better to go with the 8 inch balancer as the gear drive will tend add more harmonics then using a timing chain set up.

 

[johns79z28]

Harmonic Balancer Size

Thank you everyone for your help!!!
Since I will be doing some Bracket racing
and spend more time on the street
an 8" seems the way to go.
John