Harmonic Balancer Diameter
Thread Starter
Disabled by request 8 JUN 2025
Joined: May 2019
Posts: 329
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From: St. Augustine, FL
Harmonic Balancer Diameter
'81...350.....L81 engine. I bought a MSD timing tape assortment and need to know the diameter of my harmonic balancer. Next to impossible for me to measure it with the engine installed and it being behind the belt pulleys......6.0" dia..., 6.375" dia..., 6.75" dia..., 7.0" dia...etc. I was thinking low performance were 6 inch and hi performance 8 inch, but would prefer an exact measurement. Thanks gang.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
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From: Unreconstructed, South Carolina
Pi (approx 3.1416) is your friend
'81...350.....L81 engine. I bought a MSD timing tape assortment and need to know the diameter of my harmonic balancer. Next to impossible for me to measure it with the engine installed and it being behind the belt pulleys......6.0" dia..., 6.375" dia..., 6.75" dia..., 7.0" dia...etc. I was thinking low performance were 6 inch and hi performance 8 inch, but would prefer an exact measurement. Thanks gang.
... then Mark w/ sharpie the two points where they intersect
Take string off and lay it flat & snug ... then measure that length between the two marks ... then divide that length by Pi (3.1416) ... result is diameter
example: if your string measured between marks right at 22 inches ... divide 22 by Pi (3.1416) ... = 7 inches = diameter.,
