Harmonic Balancer. What size.

[Zone_4_Lanlord]

I recently found out my 383 engine has an internal balance harominc balancer when its suppose to have an external balancer on it. The flexplate is correct with the external balancer on it. It engine has a bad vibration to it around 1500 rpm. I'm in the process of buying the correct harmonic balancer for my engine. My question is what size do i need? 8 inch or 6.25?

 

[oldtinsmith]

Unless your 383 crank is a after market crank (that's internally balanced) or a stock crank that was balanced with heavy metal, you'll need both an external balanced damper (harmonic balancer) AND an external balanced flex plate / flywheel>

Doug

 

[megaladon6]

yes he knows that as it's part of his post.
the 8in is better overall at doing it's job, but the smaller allows the engine to rev faster. go with a good company cheap 8in and you'll be fine.

 

[oldtinsmith]

megaladon6,
Yeah you're right (I miss read the post!)! I guess I was up too late last night trying to get rid of a virus on my computer.
X2 on what megaladon6 says.

Doug

 

[Zone_4_Lanlord]

I bought a crate engine from jegs, so i guess it is aftermarket, but it still requires an external balancer and flexplate. Just wanted to know what size is better.

 

[CHRIS.O]

Like what was said above the smaller supposedly allow an engine to spin up faster. A large one dampens harmonic vibrations better. These vibrations can cause wear and drag on the rotating assembly. So in my opinion a good 8" dampner will cancel out the size difference with its superior dampening. You do not need an expensive SFI approved unit. That is a waste of money unless you race in a class that requires it. Pioneer is a good brand that is affordable. Also Summit racing has GM brand dampners if you wanna go with oem approach. Just my 2 cents.