My balanced 383

[plum70coronet]

So I have a question, and need some help with understanding...I sent my 383 to the machine shop to get punched out. Turned the crank, etc... They sent it out to get it balanced, and needed my flex plate and Harmonic Balancer, pistons, crank, rods, etc... So the question is this.. Is there a certain converter I have to get??? I have a B&M stall converter already, And I hope it will work.. These are a list of some of the parts if that matters..

Speed Pro Pistons, Forged, Flat, 4.280 in. Bore, 5/64 in., 5/64 in., 3/16 in. Ring Grooves

Ati Performance External balanced Harmonic Balancer.

B&M Holeshot 2400RPM Stall Converter..

Any info helps guys.. Just don't really understand the whole internally balanced vs externally balanced thing.. Just tryin to learn..

Thanks in advance, and Happy Easter...

 

[69Bee]

Depending on the year motor, they only verify that the flexplate (converter) and balancer are neutral balanced is all.

 

[67 B-body]

Depending on the year motor, they only verify that the flexplate (converter) and balancer are neutral balanced is all.

If the Harmonic Balancer is for a cast crank external balanced engine, then the Converter should have weights on it as well for external balanced engine.... At least that's what I recall being the case....
I have never messed with external balanced (cast crank) engines, so I'm no expert on the subject..... Just going off some old memory here!

 

[Meep-Meep]

If you are sending your 383 to be balanced then chances are it will be internally balanced like all forged crank 383's. In that case you would get a converter with no weights on it and a regular MoPar flex plate. The process is to balance the crank and rods then add the damper and zero that out. The crank becomes a mandrel to zero out the damper and flywheel. The converter is balanced at the manufacturer so if the engine balancing is done correctly no need to rebalance it. I put a TCI converter on my balanced 440 and no issues and can convert to a 4 spd if I want as long as my flywheel is balanced.

I will add that balancing a converter will require a dummy shaft to keep the guts in place. Most shops don't have this fixture so if you suspect your converter is out of balance then you may have to buy a new one or find someone who can balance it. Or just send back to B&M for rebuild.

 

[plum70coronet]

Thanks guys for the input.. I appreciate it.. Meep-Meep, I sent the 383 out, and they said they needed the harmonic balancer and flexplate.. They got the external weight harmonic balancer... and i sent them my B&M SFI flexplate.. So, beings the Torque Converter should be balanced, and they are balancing the rotating assembly, I should be fine?? That is with me assuming the Torque Converter is ok.. Which I have no reason to suspect it is out of balance.. I just don't want to throw this thing together, and have it fly apart on me.. lol..

 

[69Bee]

If you are using a B&M flexplate (and converter?), the weight is usually on the flexplate. The B&M converter will be neutral balanced.

 

[67 B-body]

"They got the external weight harmonic balancer... and i sent them my B&M SFI flexplate.. "
I keep reading your description of the Harmonic Balancer, and I keep wondering if you have the correct type....????
Your balancer (SFI Rated would be a good choice) should be perfectly balanced on its own.... The external balanced engine (cast crank type) have an externally weighted balancer....

 

[plum70coronet]

"They got the external weight harmonic balancer... and i sent them my B&M SFI flexplate.. "
I keep reading your description of the Harmonic Balancer, and I keep wondering if you have the correct type....????
Your balancer (SFI Rated would be a good choice) should be perfectly balanced on its own.... The external balanced engine (cast crank type) have an externally weighted balancer....

I'm also wondering if I have the right type of balancer...???? It is SFI approved... And externally balanced.. It has 2 different screw on weights.. I will get the part numbers together and have to check everything out.. I will find those and post soon...

 

[HT413]

Yeah, post the part numbers. If you have a cast crank, they are 'externally balanced' meaning outside the motor. The harmonic dampened and the converter have weights on them to finish off the balance of the whole rotating assembly. Most converter companies will balance the converter by putting the weights on the converter, so any flex plate will do. B&M chooses to sell specially weighted flex plates and sell all their converters with neutral weight instead.

So post the part numbers and we should be able to figure it out.

- - - Updated - - -

For example, I'm running a b&m converter as well (I think one of their holeshot converters, I'll have to check which one). Since it's a forged crank, it is internally balanced so my harmonic balancer has no weight on it, and the flex plate and converter have no weights either.

Keep in mind that B&M's stall rating system is WAY off. They rate their stalls based on like 200 lb-ft or something like that, so your actual stall might be well off of that.

 

[plum70coronet]

Ok.. sounds good HT413.. I am heading to my dad's shop this weekend.. I have everything stored there.. I will get everything and post.. Thanks...

 

[AMX364]

400 could be external balanced. All 383 should be internal balanced.

 

[Meep-Meep]

Thanks guys for the input.. I appreciate it.. Meep-Meep, I sent the 383 out, and they said they needed the harmonic balancer and flexplate.. They got the external weight harmonic balancer... and i sent them my B&M SFI flexplate.. So, beings the Torque Converter should be balanced, and they are balancing the rotating assembly, I should be fine?? That is with me assuming the Torque Converter is ok.. Which I have no reason to suspect it is out of balance.. I just don't want to throw this thing together, and have it fly apart on me.. lol..

My concern is why the external weight damper? It should have no offset weight at all. It is common to have your old original damper trim balanced but nothing excessive to correct it. If you have a new converter like a B&M or TCI then it should be balanced. The flex plate should not have any offset weight either. Again, I am assuming the crank is balanced internally, meaning no extra weight needs to be added. Note about externally balanced engines. This is a trick used by the factory when they need to add more material to the counterweights. It's cheaper to just throw some weight at the extreme ends then to add heavy metal to the crank. Also, external weights are not good if you plan to spin it to very high RPM's (full race engine territory).