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atcoscrazyest69 10-09-2012 10:05 PM

broken crankshaft
 
well i have a 400 sbc and i pulled my pan to figure out were all these metal shavings in the oil was coming from and found the crank is broken right at the hole in the front of the crank the journal for #1and 2 need help as i have never replaced a crank the right way i was talking to the guy at summit about getting an internally balanced crank and he stated that i should get the whole rotating assembly balanced ? anyone have any input

crankshafthttp
://www.summitracing.com/parts/ESP-10400375057I/

vinniekq2 10-09-2012 10:27 PM

whats the question? if the block is good/straight/square,then you can buy a kit and rebuild the short block.May as well freshen the top and regasket it all and put it back to work.

atcoscrazyest69 10-09-2012 10:58 PM

the question is when i buy this crankshaft to i need to get my whole rotating assembly balanced? isnt the crank already internally balanced? also it looks like brown mud inside of my coolant passages any good way of cleaning it real good ?

vinniekq2 10-09-2012 11:10 PM

When ever you build an expensive ,hi output engine,balancing is cheap insurance.I get all the pieces balanced,or checked

cdminter59 10-09-2012 11:12 PM

broken crankshaft
 
You can choose either a internally balanced rotating assembly Eagle Specialty Products B13470030 - Eagle Street Performance Rotating Assemblies - Overview - SummitRacing.com or a externally balanced rotating assembly which includes main & rod bearings and a balancer and flexplte. Eagle Specialty Products B13460030 - Eagle Street Performance Rotating Assemblies - Overview - SummitRacing.com Have the block cleaned, bored .030, new cam bearings, freeze plugs, and screw-in oil gallery plugs you have abrand new short block. You then what heads to use. New or rebuilt.

atcoscrazyest69 10-09-2012 11:20 PM

Well its already. 30 over and and cleaned but i ran whater threw it instead of antifreeze like a *******. Just out of curriosity whats it normally cost to get an assembly balanced?

vinniekq2 10-09-2012 11:29 PM

there are two types(generally,theres actually more) close enough is a 2 gram or less accuracy,then a precision zero balance which is as close as possible to perfect. dont worry about under balance,,,,
costs vary depending on time spent. I pay about $500.00.Ive seen it done for $200.00. some builders just static balance which isnt all that great,

atcoscrazyest69 10-09-2012 11:35 PM

So i figure 500+260 for the crank im better off getting the rotating assembly shown above for 780? And just putting it in. Right? I dont need to get the one shown above balanced? The internally balanced one?

atcoscrazyest69 10-09-2012 11:41 PM

Well its already. 30 over and and cleaned but i ran whater threw it instead of antifreeze like a *******. Just out of curriosity whats it normally cost to get an assembly balanced?

atcoscrazyest69 10-09-2012 11:58 PM

Sorry. That one skipped past me.

59RAMBLERSUPERWAGON 10-10-2012 12:38 AM

If I were in your shoes, I would go with the ballanced rotating assembly, no waiting, no hassle, but with that much metal in the engine I would be concerned about metal in lifters, passages, etc. I have rebuilt enough motors to know that starting with everything clean, saves wear down the road.

Pull the block have everything cleaned, throw in the rotating assemble and put it back in. I am not a professional, but I am experianced and I would hate to see you throw 700 bucks into a motor that gets damaged due to old shavings in the motor.

Mr. P-Body 10-10-2012 08:00 AM

The entire rotating assembly does NOT need to be "rebalanced", only the crank itself. When they advertise "internally balanced", they don't mean it's already balanced, they mean it's suited to the internal versus the external. Since this is a 400, it IS externally balanced "stock". If you get an "internal" crank, you'll need a new balancer and flywheel/flexplate.

The imported cast cranks have shown to be a lot of trouble. The only "cast" crank we use for a 383/400 is the genuine Chevrolet. That nodualr iron crank is pretty good. The forgings from Eagle, etc. are quite good.

A balance "job" is $200 here (Richmond area). When converting to "internal", it can get expensive due to the cost of the "heavy metal" (tungsten) and the labor to install it. I've never heard of varying "degrees" of balancing costs, based on "how far". All the shops I know balance to within 1 gm. SAE standards are 1/10th of 1% of the entire rotating mass. In the case of the SBC, that's about 25 gm.

FWIW

Jim

atcoscrazyest69 10-10-2012 09:35 AM

Well i planned on gettin her all cleaned up. Ok just so i got this right if i get this kit Eagle Specialty Products B13470030 - Eagle Street Performance Rotating Assemblies - Overview - SummitRacing.com i will not need to get it rebalnced? Just put inu and go?
Thanks for all your help guys!

Silver Surfer 10-10-2012 11:23 AM

Quote:

Originally Posted by atcoscrazyest69 (Post 1597869)
Well i planned on gettin her all cleaned up. Ok just so i got this right if i get this kit Eagle Specialty Products B13470030 - Eagle Street Performance Rotating Assemblies - Overview - SummitRacing.com i will not need to get it rebalnced? Just put inu and go?
Thanks for all your help guys!

No. You MUST get it balanced. Internally balanced mean that you do not need a special flywheel/flexplate and harmonic damper to achieve balance. Factory SBC400's had additional weights on these components to make this work. Internally or externally balanced rotating assemblies both need to be balanced, the difference is how it is achieved. It is two different styles/methods.

You can get this kit but you must:
1) have it balanced

2) buy a new flywheel/flexplate for internally/neutral balanced SBC's, like a SBC350 . Aside from the fact of the balance issue, the link you posted uses a 1 piece rear main seal, which uses a different crank so you old flywheel will not even come close to physically bolting on.

3) buy a new harmonic damper for internally/neutral balanced SBC's, like a SBC350

atcoscrazyest69 10-10-2012 11:34 AM

The link i posted is a 2 piece rear seal? And i understand the balancer and flywheel stuff but in the link i posted it also says it is balanced so i am confused


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