I have a 383 rotating assembly lying around, and I'm seriously thinking about using it if I can find a damper for a reasonable price. I'd need a standard 383 external balance for an LT1...I think I've seen them somewhere, but dont remember where. Can anyone help me out here?

 

ttt

 

is the rotating assembly for the 1 piece main seal blocks?

 

Yeah, the whole thing is sitting in my shop waiting to get assembled into a late standard bore 350 block. All I would really need is a balancer.

 

Lt1 front balancers are nuetral. Rotating assembly + flywheel/flexplate is external.

 

Right, but what I'm saying is that my 383 has an external balance front damper (400 style) since it was made for a late model non-LT1 engine...if I were to get an external balance LT1 damper (if there is such a thing) I could use the whole rotating assembly in my LT1. The flywheel is balanced the same as any stock LT1.

 

is that a forged crank?

 

ah i see what you are saying. You may try taking a stock lt1 dampre along with your 400 dampre to the machine shop and see if they can match the balance of the one to the other.

Another option is maybe see if fluidampre or ATI will put a lt1 outter shell on a counterweighted center for you.

 

Yes, it's a 4340 forged 3.8" stroke cola crank made for the ZZ383 GM crate motor. I upgraded the rods from the PM 5.7 to Eagle 4340 5.7 rods. My problem with the motor is that the pistons are special with the 1.396 compression height...so I had to use the existing 18cc hyperutectic pistons for now but they are nice, coated skirts and metric rings. the stroke makes a 383 with a standard bore engine instead of the 3.75/ +.030" 383 combo. I'd use this for now if I can find a solution to the damper question...I know everyone with a 383 or 396 LT1 couldn't all be using 6.0" rods!

 

i would think a 1 peice main cola crank would be internal balance. never seen on like that.

you could have it internally balanced. since its 4340, its not like it would be a waste of money to go that route.

 

Internal balanceing that crank would cost a fortune! They had to make four deep cuts in the weights on the crank to get it to balance like a standard 350 due to the stroke. The mallary aint cheap. If I was going to do that for a few bucks more I could just buy another rotating assembly...

...only option is to use an external balance damper if I were to use it.

 

if its balanced like a 350 it should be internal balance.

 

im seriously not finding any cola part numbers for a 1 peice seal 350 mains for the 26oz imbalance.

 

well we do it for $250 heavy metal is $50 a slug but i doubt you would need any. where can you buy a complete rotating assembly for $250?

 

OK. I seem to have confused you guys.

The crank is a cola. The rear is balanced just like a 350 so it can use interchangeable flexplates and flywheels. The front however is just like your typical 383, having a weighted damper instead of a neutral one. A few phone calls confirmed that the weight on the damper is the same as that of your typical 3.75" 383. That's why there was so much metal taken out of the crank.

No, I can't get a rotating assembly for $250, lol. what I meant was after buying a crank like that and paying for metal and then balancing it all, I could just get a 3.75" internal balance crank, pistons and rods for a little more and not have to deal with these issues. This rotating assembly was designed for a gen 1 small block, not a gen II.

I think when people refer to an 'internal balance' rotating assembly it refers to the damper mostly. I've read that the LT1 is 'internally balanced' for that reason. However. I've also read that the late non-LT1 engines are 'external balance' due to the counterweight on the crank, even though the damper is neutral as well. I just refer to late engines as internal balance since they all use weighted flexplates and flywheels, but have neutral balancers. Also, when you buy a stroker crank or something for an LT1, they're 'internal' so they can use the LT1's neutral balance damper (they require 6" rods to clear). It can be confusing For those that buy an external balance stroker crank, they'd need alot of good balancing, or an externally weighted damper to make it work. That's what I'm looking for.