The 428SCJ is externally balanced using a separate "hatchet" that slips
on the snout of the crankshaft behind the balancer. Other 428's are
externally balanced but the SCJ used heavier LeMans capscrew rods and
required the extra balance weight. IIRC, 1U is a standard 428 crank,
1UB is the 428CJ crank and 1UA is the 428SCJ crank.

> I always though it was both as with all engines ie harmonic, crank. flywheel
> etc? Is the428 scj diff? Or am I just daft :-)

Two separate issues. One is harmonic damping which the balancer provides.
The second is counterwighting to offset the mass of the crank throw, rods,
and pistons. If all the mass is contained inside the crank, it's internally
balanced (zero balanced). If some of the mass is external (on the flywheel
and balancer, or an external hatchet), it's externally baalnced (sometimes
known as Detroit balance).

quote:

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Originally posted by Joe Grippo:
How are 428 SCJ's balanced?
Internally or Externally?

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Externally with it's own unique balancer and flywheel/flexplate.

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Alex Denysenko
Co-Administrator and Moderator

NHRA/IHRA/SRA member and licensed Superstock driver
NHRA and IHRA SS/LA & SS/MA National Record Holder '00,'01,'02,'03,'04 &'05
First SS/MA in the TENS!
IHRA division 5 Superstock Champion
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28

The Barry of BarrysGrrl

quote:

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Originally posted by majik455:
Daniel that was alot of good stuff :-) and all new to me I was just told to always balance rods crank flywheel and pistons. So if the crank counters the force of piston throw..does the harmonic bal counter forward weight on motor? ie powers steering alt etc? or does it counter flywheel? I get lost here

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Here let me give you another one to think about. If you have an automatic. What about the weight of the converter. Just like a stick has the presure plate and clutch disk. Makes you wonder how much affect it all has on things.
I'm having a motor balanced and blue printed now. After starting with a bare block. Everything else is all new. I got a call telling me I needed to send the balancer and flywheel so he could finish it up. I didnt bring up the small heavy converter......lol

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1967 GT Fastback S code, C6, 4:56, tubbed, 10 point cage.
Pictures in link.
http://www.allfordmustangs.com/forums/photopost/showgallery.php/cat/500/ppuser/12578

quote:

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Originally posted by Joe Grippo:
How are 428 SCJ's balanced?
Internally or Externally?

---

The 428SCJ is externally balanced on both the front and rear end of the rotating assembly. The "cookie cutter" on the front snout provides external balance for the front of the "1UA" crankshaft while a offset weighted flywheel provides external balance at the backend. The damper itself is not specific to a 428SCJ as it's zero balanced and can be used on any of the Fe family engines. On the other hand, 428's using the 1U or 1UB cranks are zero or neutral balanced on the snout end but are external balanced on the flywheel end. This is possible due to an additional counterweight on the 1U and 1UB crankshaft that permits the snout or front end of the crank to be neutral balanced. The 1UA crank is missing this additional crankshaft counterweight and thus requires the "cookie cutter" on the front of the crank to add the additional counterweighted mass to the rotating assy.