Ive been getting a lot of mixed answers, this is just for a mild street strip engine.

If you buy a new 454 crank (scat cast), does it need machining, or is it just a bolt in.

If you need a new external balance flexplate and dampner, is it just a bolt on thing or do they need to be balanced the same?

These aren't about my engine, but I never really understood the internal/external balanced engine thing, so i figure id ask. Thought i knew, then someone said i was wrong, just want to know where i stand.

Thanks
-Ryan

------------------
1970 Malibu 454 (http://www.chevelles.com/showroom/malibdreamer.jpg)

<BLOCKQUOTE>quote:</font><HR>Originally posted by MalibuDreamer:
if you buy a new 454 crank (scat cast), does it need machining, or is it just a bolt in.
<HR></BLOCKQUOTE>

When I built my 454,I bought one.I brought it to my machine shop,and he said it would take $400 worth of labor/heavy metal to make it correct.I promptly returned it,and just got a crank kit.Just my experience.



------------------
My 70 SS396 (http://www.chevelles.com/showroom/mr4speed70SS1)
Engine pic (http://chevelles.com/showroom/mr4speed70SSengine2)
My Black Cherry 70 SS454 (http://www.chevelles.com/showroom/mr4speed/Picture025.jpg)
The launch (http://www.chevelles.com/showroom/CClaunch.jpg) 13.13 @ 101.490/1.92 60 ft. with radials,2.73's,and thru the mufflers
1.90 Best 60 ft.
101.84 Best MPH
My Drag Race page and combo (http://www.prestage.com/site/site_display.asp?SiteID=589)
1968 Oldsmobile Cutlass convertible
1985 Cadillac Eldorado (daily driver)
Chris Corwel,TC Member # 785
Member # 141 AMCA

The reason one engine is internally balanced and another isn't generally hinges around available crank room deep inside the block.

When you get into long stroked, big bore engines, the counterweights have to be made bigger in diameter so that they can balance everything. If there isn't enough room in the block for bigger counterweights, then the needed weight is added to each end onto the flywheel or flex plate and harmonic balancer.

The crank is balanced, but isn't truely balanced uniformly like an internally balanced crnk b/c the extra needed weight isn't uniformly distributed along the crank.

And in extreme power applications some say that the weights on the cranks ends can actually bow the crank at really high rpm's and power levels. That's why the better, more pricy cranks are generally internally balanced...

One other point is that stroked cranks generally need heavi-metal to help balance them b/c the stock diameter counterweights don't have enough weight to balance out the longer throw and bigger pistons..

That's if the counterweights are stock diameter, otherwise you will probably be grinding your block for needed clearance to accept the bigger counterweighted crank!!!

Hope this helps... pdq67

Ryan,
It depends on the crank that you buy and what you are using for pistons and rods. If you are using stock pistons and rods, and the crank is balanced to the GM factory spec, which is just an average, then you can probably install it and will never feel any difference. As soon as you change any parts from the factory weights, such as pistons, you really should rebalance the crankshaft to the weights of the new parts. 99.9% of the 454's in the world are externally balanced. The only ones that are not are generally high output, race only, engines. The flywheels and dampers for an external balance 454 shouild be a bolt on deal if they are from a reputable manufacturer.
It would do you a world of good to go to a local balance shop and ask to see how the balancing is done. I would think that any good shop would be willing to show you in hopes of getting a future customer. Seeing the operation in person is the best way to understand it.
Hope this helps,

------------------
Bill Koustenis
Advanced Automotive Machine
Waldorf Md

1971 Heavy Chevy - original owner
Team Chevelle #100

Thanks for the help guys,

I had my crank (GM cast) done at a different shop (Merkle) in cooperation with the shop that was rebuilding my rods and building my 454 shortblock, but im not sure if they changed the balance of the crank to the exact pistons i am using TRW H426's (Hyper .100 dome). I think they may have kept the crank at stock settings.

I really can't put any more money into this block, and my engine builder told me not to worry. Should I??