external balance harmonic balancer ?

[rpdg14]

sbc 350 1pc seal external balance rotating assembly. balanced eagle rotating assembly, crank, rods and pistons. factor hydraulic roller set up. I have the external balance flywheel. my question is do i need an external balanced harmonic balancer or will a standard internal balanced sbc 350 balancer work. also what inch balancer do ya advise using.

Thanks
rpdg14

[MarkM66]

I've never heard of a externally balanced 350 . Why did you get a externally balance crank?

[Vegas69]

If it is in fact external balance, you must have an external balance piece on each end of the crank.

[GregWeld]

ALL SBC with one piece rear main seals are EXTERNALLY balanced. All two piece seals are INTERNALLY balanced.

If you build a 383 stroker - that would be EXTERNALLY balanced.

Use the correct flexplate / balancer.

You asked about what SIZE of balancer - and that depends on clearance if any issues depending on what you're putting the motor in. And you should talk to your engine builder to determine exactly what balancer to use. Some balancers have different weight IMBALANCE etc so this is a trickier question than just "what size" -- getting it wrong will have bad consequences so don't guess.

[MarkM66]

Opps, I missed that oprm part. I built one of those for my Nova and I remember that I supplied them with a neutrally balance flywheel, and they had to take some weight out of one side.

Is the engine currently put together? I would think the machine shop would request the damper and flywheel to balance the rotating assembly.

[SLO_Z28]

Is the engine currently put together? I would think the machine shop would request the damper and flywheel to balance the rotating assembly.

^This. You have to balance it as an assembly.

Just buy whatever the machine shop that does the balancing recommends/sells, they're getting it for a better price than you ever could, and will sell it for less than retail. I used to use the TCI Rattler, its a good unit, and we used to retail it for $350.

[rpdg14]

the motor was purchased out of a repo 90's camaro for 250.00. short block heads and intake was all that was on the motor. when we broke the motor down we discovered it had never been run. this is when we found the eagle roating assembly in it. the pistons are summit 2 valve relief flat tops. research showed the kit was an eagle balanced assembly possibly purchased from summit since it is listed in there catalog. i had to call eagle to find out more about the assembly. they advised it was an external balanced 350 crank and i would have to use an ext balanced flywheel and yes i forgot to ask about the balancer. a lot of extra parts were in the trunk of the camaro but i did not think to get them because i figured it was a normal sbc 350 and we had plenty of flywheels and harmonic balancers at the shop, boy was i wrong. as far as asking my engine builder, well that is my dad and we work on vehicles as a hoby and he has never fooled with an external balanced 350 before. i hope i did not type to much. thanks for all the recomendations.

again thanks
rpdg14