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Folks, I'm preparing to build a Chevy 383 stroker which will live on the street in a pickup truck and I have a couple questions about the rotating assembly.

First, let me say that I'm building the engine pretty much from scratch. So far I have a 2007 marine 350 which I hope will donate the vortec heads, manifold, 4-barrel, ignition system, maybe rods, pushrods, some small parts. I can't see using the block 'cause I think it's been run in salt water and I know better than to trust it after that. But I also have a good 4-bolt 2-piece rear main seal block. So I'm thinking about the rotating assembly for now.

Assuming I use my standard rods, can I use an internal-balance crank if I choose the right pistons? If yes, is there any advantage to doing this? Is the external-balance crank just as good and any less expensive? I'm not stuck on using the rods I have, but would like to if possible 'cause I want to hold costs down. I don't have any flywheel or balancer yet.
 

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From experience, don't buy the budget cast Eagle 383 crank. Supposedly internally balanced already, cost me $450 in mallory to get it balanced and now my stock 5.7 rods don't fit the journals so I need to get the rods milled down to fit.
 

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I don't know what you did wrong but I sell 20+ Eagle cast cranks per year. Mostly used with stock type or Eagle/Scat I beam rods. Balance man loves em. Says the counterweights are easy to set up and drill.

None of the aftermkt cranks are vendor balanced close enuff. You are wasting your money to pay extra for them. Take the final assembly to a competent shop and have a 1/2 gram balance done.

I have one in my "T" bucket with a blower on it. NO PROBLEMS at all. Cept for the tire smoke and white knuckles..
 

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I don't know what you did wrong but I sell 20+ Eagle cast cranks per year. Mostly used with stock type or Eagle/Scat I beam rods. Balance man loves em. Says the counterweights are easy to set up and drill.

None of the aftermkt cranks are vendor balanced close enuff. You are wasting your money to pay extra for them. Take the final assembly to a competent shop and have a 1/2 gram balance done.

I have one in my "T" bucket with a blower on it. NO PROBLEMS at all. Cept for the tire smoke and white knuckles..
Bob, were these 5.7" rod 3.75" stroke INTERNAL balance cranks like Speedfoos has?? I've only ever seen minimum 6.0" rod length 3.75" stroke offered in internal balance.

I have yet to find anyone selling an internal balance 3.75" stroke cast crank that uses rods shorter than 5.85-6.0". Rarely do you even find a forged 5.7" rod 3.75" stroke crank meant for internal balance. Seems they all take some mallory to do the job.
 

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Sorry I was talking externally balanced as the original question was asked.

About the only real problem I've had with the Eagle cranks as to balance, was a customer had an extremely light weight set of rods and some ultra-light pistons. The crank wouldn't balance because there was no counterweight area where the balance machine wanted a drill hole. This was a steel crank tho.

I have had to jocky some bearings around to get proper rod and main bearing clearance. Luckily I have bearings from .0003 over to .002 under and a good polisher.They could do a bit better in this area. But their product is far better than the CAT offerings of a few years ago.
 

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I don't know what you did wrong but I sell 20+ Eagle cast cranks per year. Mostly used with stock type or Eagle/Scat I beam rods. Balance man loves em. Says the counterweights are easy to set up and drill.

None of the aftermkt cranks are vendor balanced close enuff. You are wasting your money to pay extra for them. Take the final assembly to a competent shop and have a 1/2 gram balance done.

I have one in my "T" bucket with a blower on it. NO PROBLEMS at all. Cept for the tire smoke and white knuckles..
Unless I got ripped off and serviced without lube, that's what it took. I'm happy you've been selling them for so long without issue. I got screwed on the one I bought and will never buy another one.



 

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Speedfoos, just to clarify for others who might read this...
It appears to me that you bought an internal balance 383 crank without realizing that it was 6" rod only, as most 3.75" stroke internal balance SBC cast cranks are. It was then taken to the shop with stock 350 5.7" rods and heavy pistons for the balance job. Since the crank counterweights were configured for the longer 6" rod, their size put them in conflict with the bottoms of the pistons at bottom dead center, due to your using 5.7" rods. So, the shop "cut" the offending area off the counterweights and then "put it back" using mallory. It is obvious looking at the "flattened" counterweights shown in the pics.

A better shop would have stopped and informed you of the problem first, allowing you to make changes to the parts used(different rods/pistons, or send crank back)rather than "hacking" on the crank to make it work. That is a hack balance job, all they saw were the $$$ they could fleece you for. :(
 

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I have had to jocky some bearings around to get proper rod and main bearing clearance. Luckily I have bearings from .0003 over to .002 under and a good polisher.They could do a bit better in this area. But their product is far better than the CAT offerings of a few years ago.
As far as I am concerned, this is unacceptable to have to do this just to use the crank. Yes, they are better than CAT(what isn't :rolleyes: ), but fall well short of SCAT's quality.
 

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ericnova72 said:
Speedfoos, just to clarify for others who might read this...
It appears to me that you bought an internal balance 383 crank without realizing that it was 6" rod only, as most 3.75" stroke internal balance SBC cast cranks are. It was then taken to the shop with stock 350 5.7" rods and heavy pistons for the balance job. Since the crank counterweights were configured for the longer 6" rod, their size put them in conflict with the bottoms of the pistons at bottom dead center, due to your using 5.7" rods. So, the shop "cut" the offending area off the counterweights and then "put it back" using mallory. It is obvious looking at the "flattened" counterweights shown in the pics.

A better shop would have stopped and informed you of the problem first, allowing you to make changes to the parts used(different rods/pistons, or send crank back)rather than "hacking" on the crank to make it work. That is a hack balance job, all they saw were the $$$ they could fleece you for. :(
Even worse. This is what I bought.

http://www.summitracing.com/parts/ESP-103523750/

Externally balanced Eagle crank.

That means mine got converted to an internally balanced crank. Jeezum crow. This first time building a small block is really kicking my butt and my wallet. I brought them everything I had (FW, crank, rods, pistons) and asked them if I had everything needed to balance it. It was even in the original box with the part number on it. They said "yup" and sent the crank off for balancing to some yokel, and then weight-matched the rods. Me, not knowing enough about these engines (I'm a recently converted Honda guy), nodded dumbly over the phone when they told me what it needed before adding the heavy metal.

Nice. Moffitt Machine shop in Fayetteville, NC for the rest of you to stay away from. I sure am learning from my very expensive mistakes.

At the OP, sorry for the thread jack.

- clint
 

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speedfoos said:
Even worse. This is what I bought.

http://www.summitracing.com/parts/ESP-103523750/

Externally balanced Eagle crank.
Went to Eagle's web site, as usual(starting to see this alot) Summit left information out in this description. This part # is available with 5 different balance types: Internal/5.7 rod, Internal/5.85 rod minimum LT1, Internal/5.7 rod LT1, Combination/Internal front-external rear 5.7 rod, and External/5.7 rod. They just add letters to the basic part # to alter the balance type, but no way that all these come from the same crank casting.
 

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I know this is an old post but did Eagle produce a cast internally balanced crank for 383 5 years ago?........That's when my engine was built and has sat until now. I have an external flywheel and looks to be an internal PB harmonic balancer (No weight bars on backside). I have a vibration on light acceleration but none at adle or even gassing it in park......spending today tracking it down.
 

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I know this is an old post but did Eagle produce a cast internally balanced crank for 383 5 years ago?........That's when my engine was built and has sat until now. I have an external flywheel and looks to be an internal PB harmonic balancer. I have a vibration on light acceleration but none at adle or even gassing it in park......spending today tracking it down.
Is this in a 1-piece rear main seal block?? If so, yes they did, it is listed as "combination balance" and uses a no offset weight neutral harmonic balancer with a stock 1-piece seal weighted flexplate.
 

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oops, sorry, its a 2 piece RMS.......
They offer an Internal, and an External balance...but no "combo" balance in 2-piece.

Either the balance shop did something hinky, or you've got either the wrong balancer, or wrong flexplate....don't know how your going to figure out what is going on there...either trial and error by swapping parts(balancer, flexplate) one at a time, or pulling it apart and having balance checked
 

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They offer an Internal, and an External balance...but no "combo" balance in 2-piece.

Either the balance shop did something hinky, or you've got either the wrong balancer, or wrong flexplate....don't know how your going to figure out what is going on there...either trial and error by swapping parts(balancer, flexplate) one at a time, or pulling it apart and having balance checked
I am thinking its my external balanced flywheel......internal type balancer was installed at assembly by Kevin Turner out of Kentucky.......wouldn't it vibrate at idle and revving it though in Park?
 

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Howards track smart forged 383,Scat stroker clearance 5.7 rods,I-Con pistons,Kings bearings.Facing Mallory metal balance.180grams light in the front and 200grams in the rear.2pcs conversion to 1pcs.Got neutral balance with SFI H/B and bolt on balancer plate on rear.Can use any F/P or F/W as needed depending on application.
 
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