[69redbird]

What is the diiference in externally and internally balanced? Is there a size diffence? My buddy says his motor will not fit in his car because it is externally balanced. Thanks

[SLICK1]

WELL TO ANSWER YOUR QUESTION, SOME AUTO MANUFACTURERS LIKE CHEVY (with the 400small block & 454 big block) & FORD (several of their small blocks) USED COUNTER WEIGHTED HARMONIC BALANCERS AND OR FLEX PLATES OR FLYWHEELS TO BALANCE THIER MOTORS THAT WOULD HAVE BEEN DIFFICULT AND COSTLY TO BALANCE INTERNALLY! BUT A LARGE MAJORITY OF MOTORS PRODUCED WERE BALANCED INTERNALLY, WITH THE RECIPROCATING ASSEMBLY: (meaning pistons, pins, rods,rings,balancers, flex plates and or flywheels) HAVE TO BE PREPARED TO MEET THE BOBWEIGHT (rotational weight of the crank counter weights) WHICH IS MEASURED WHILE SPINNING THE CRANK AT A PREDETERMINED SPEED! NOW ONCE THATS DETERMINED A COMBINATION OF PROCESSES ARE PERFORMED, THIS COULD BE DRILLING OF THE CRANK TO REDUCE WEIGHT OR ADDING HEAVY MALLORY METAL TO IT TO INCREASE WEIGHT, AND THEN CHECKING THE BIG AND SMALL ENDS OF THE RODS SO THEY ARE EQUAL, THE PISTONS, THE RING PACK, AND PINS AS WELL TO SEE THAT THEY ARE WITHIN GRAMS OF EACH OTHER! SOUNDS VERY TIDIOUS, BUT IT'S REQUIRED TO HAVE A MOTOR REV & PERFORM AT IT'S BEST! NOW PLEASE EXPLAIN WHY HE CAN'T GET THIS MOTOR IN HIS CAR? I'M DYING TO HEAR THIS.

[Jack Ferris]

[NOW PLEASE EXPLAIN WHY HE CAN'T GET THIS MOTOR IN HIS CAR? I'M DYING TO HEAR THIS. [/QUOTE]

Me Too

[69redbird]

Guys,

Can an external balanced motor be swithed to internal balanced? Can the 400 block be torn apart and put a new balanced rotating assembly? The project my buddy is working on is a fiero kit car, and the motor is cheby sb 400. He says he wants to trade a sbc 350 for it so it will fit? Thats why I asked if the was a size difference. I will have to talk to him about more details. Thanks

[dammen8]

yes a 400 sbc can be internally balanced, but it is sometimes costly

[69redbird]

Hey,

What kind of cost are we looking at? Is it good still if its external?

[screamingchief]

I think what your friend was refering to is the fact that most externally balanced SBC (ie.the 400 style engines) use the 8" diameter balancer,which is a pretty big honkin balancer,that might be getting in the way in that little ole' fiero engine bay somehow...

The internally balanced SBC can use any one of three different balancers diameters IIRC.
(two are smaller than the 8" diameter balancer is)

[Thumpin455_GTO]

Also the 400 uses a somewhat rare flywheel. A 350 or other sbc flywheel wont work with the 400. Tell him to use a Toronado/Riviera transaxle and a real engine, like an Olds or Pontiac. He will break less stuff that way and make alot more power.

[69redbird]

Ok Guys Here is why the sbc will not fit in the ferio:
My 400 was purchased to go in the a Lamborghini kit car with a extended fiero frame. I had to purchase the V8 Archie kit to adapt the V8 into the fiero using the stock transaxle. After purchasing the kit and attempting to put it in the car I noticed that the harmonic balancer was going to hit the frame; therefore I was going to have to make some serious frame modifications. I call the V8 Archie company and was told that a 400 will not fit due to the fact that it's externally balanced. The only thing that will fit is a 350, because they're interally balanced.
I hope that long explanation helps. Otherwise the engine is perfect.