Let's discuss 4.00" crank balancing...

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dusterdoug

dusterdoug

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Two sub topics of discussion:

1) I assume that it would take a lot of metal to internally balance a 4.00" CAST crank. Anyone do it and what was your cost? With what pistons?


2) Has anyone dared to run a 4.00" cast crank that with an EXTERNAL balance?
 
mallory/tungsten has gone up quiet a bit, could cost upwards of 400 dollars.

ive internally balanced quiet a few cast cranks, 4'' included.
 
...and that's just the cost for the metal. At least here. I tried to get a recent build I am doing for a member internally balanced and my machinist was talking about 600 plus. Yeowwwwww.
 
RustyRatRod said:
...and that's just the cost for the metal. At least here. I tried to get a recent build I am doing for a member internally balanced and my machinist was talking about 600 plus. Yeowwwwww.
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ouch, standard balance starts at 145.00 but when you have to add the amount needed for and external crank...thats when it triples and in your case quadruples.

external is fine, as long as its right.
 
Exactly. I think people get too caught up in what goes around forums. With a good balancer and balance job, they will whiz right up there. Tons of um have been raced hell out of with the stock bottom end.
 
I've balanced well over 40 cast 4" crankshafts for small block mopars. Use lightweight pistons and rods, no heavy metal needed usually end up removing 60 to 100 grams of metal off each end.
 
OLDSTYLE said:
I've balanced well over 40 cast 4" crankshafts for small block mopars. Use lightweight pistons and rods, no heavy metal needed usually end up removing 60 to 100 grams of metal off each end.
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You bring up an interesting point of view. This motor that we're thinking of, in addition to the cast SCAT crank, will use the SCAT I-beam rod, and fairly light Wiseco piston.

I would guess those who use the heavy H beams, even with a lighter piston could have to add metal..?????????

OEM rods are...what: 750-ish grams?
H beams are typically at...675+?

Scat I beams are...590 based on the last set I bought.

Vedddy, vedddy intra-sting...
 
I have a Scat 4 inch forged crank...scat i beam rods..and Icon pistons (507/118 grams)...crank took two slugs of mallory to balance...
 
Tony, that's what I would have guessed. But... I'll get another set of Scat rods and lug it all to the machinest and see where we stand.

Anyone have any thoughts on an external balance for a 95% street application?? I know of quite a few externally balanced 383 and 406 brand X motors that run pretty good....
 
70aarcuda said:
I have a Scat 4 inch forged crank...scat i beam rods..and Icon pistons (507/118 grams)...crank took two slugs of mallory to balance...
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Tony that seams strange to me. Are you sure the rods aren't H beam rods?

I say that because, your set up is the same as me (my icons are flat tops)

There was no mallory added.

balance sheet
Piston 497g, pin 125g, rings 50g, spiro locks 4g, rods 563g, I don't claim to understand the rest of my sheet.... Insert 44.5g, Rotary 903g, Rescip % 834.5g, Bob Weight 1737.5


I never saw the crank before it was balanced but there is several holes drilled in to the counter weights.
 
Yes..they are Scat I beam rods...

but after second thoughts..the crank is a forged MP 4 inch stroke..I was assuming it is made by Scat...
 
70aarcuda said:
I have a Scat 4 inch forged crank...scat i beam rods..and Icon pistons (507/118 grams)...crank took two slugs of mallory to balance...
Click to expand...

Yes My Forged Scat 4" took 2 slugs also. Scat H Beams and Custom Weisco Pistons. I don't know why it is like that. It should come a heck of a lot closer for how much the crank costs.
 
It sounds like the weight of a forged crank is the same as balancing a cast crank. ?

Just FYI, my stock stroke (3.58") eagle forged crank did not need mallory with eagle forged H beam rods and keith black forged 40 over pistons (&rings)

I was tempted to buy the light crank, am so glad now that I did not!
 
dusterdoug said:
Anyone have any thoughts on an external balance for a 95% street application??
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Yeah, my engine builder does. He's a well respected Mopar machinist/engine builder and he thinks I'm wasting my money by going internally balanced. He said for a street car like mine, that might make it to the strip occasionally it's not necessary. I trust him and value his opinion, but we are still going to try and balance it internally unless the cost of the mallory metal becomes prohibitive. I'm not going to pay $500 just so I can say that it's internally balanced.

BTW, it's a forged Scat crank, H beam rods and Icon pistons.
 
70aarcuda said:
Yes..they are Scat I beam rods...

but after second thoughts..the crank is a forged MP 4 inch stroke..I was assuming it is made by Scat...
Click to expand...

Yeah, i thought the MP forged cranks were Scat as well.

I had my machinist build my stroker package. Told him my long term goals was to spin it at 7500 rpm. That's what he set me up with.(It will be lucky to turn 6000 rpm to start with)

Just a interesting note!
Tony, was you stroker baste off of a 340 or a 360?

I when on the scat site and the 360 "4" forged crank is 2 pound heavier then the 340.
Mine is based off of the 360.
 
my scat 4'' and h beams took 314.00 dollars of Mallory in 2008 2 slugs maybe .not sure now
 
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