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broken crankshaft
Have you considered going to your local Napa store and order a remfd crank kit? It will be a Chevy nodular iron crank with bearings not some chinese cast steel.
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I have and it would be much easier but i was under the impression that cast steel was stronger. And my famous question if i got the crank from napa do you think it would need to be balanced?
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I worked as a engine tester at the Tonn Chevy Plant when the 400's when being built. We would balance those engines in the test stand. We almost never rejected a engine because of the flexplate being out of balance. All the balancing was done with oz pins driven into the balancer. We didn't have a welder to add wt or change the wt to those flexplates. Where they balanced to race tolerances??. Certainly not.
I have read through this thread. My suggestion would for this O/P to take the block to a machine shop to have it checked to see if it needs to be line bored/honed. And as stated have the rods checked as well. Then have the block hot tanked,rifle brush cleaned,new soft plugs and cam bearings. My Howards 383 crank states clearly on the side of the box any alterations to the crank,you then own it. |
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broken crank
Read this article from Eagles website. It has all the infomation you want to know. Eagle Specialty Products, Inc.
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I stated quite clearly, the factory nodular cranks are superior to the cast steel. Like Bogie, I do this stuff for a living. The Chinese FORGINGS are better than the factory nodular, IF you choose a good one. We've seen LOTS of balance issues with Scat cranks. Not so many with Eagle. We too, buy them in "pieces". Seldom to kits have all the correct combination for optimum performance. We generally use different pistons and bearings than Eagle supplies. Their rods and cranks are as good or better than any.
RED FLAG! Crank kits may or may not be a good idea. For a pickup truck "to get down the road", they're usually okay. For any performance application, they can be a real roll of the dice. Companies like CRI (Crankshaft Rebuilders, Inc.) and "Standard" (East Coast remanufacturers) are perfectly willing to weld up a torn up journal on a cast crank. This is bad. A casting isn't receptive to welding like a forging. It changes the surface tension, a known "sore spot" in castings. If you find one that's 10/10 or 20/20 (.010" or .020" undersize on both mains and rods), you have a good chance it's not been welded. It shold be magnafluxed before being used in a performance engine. They also usually come with the cheapest bearings known to man. Not ALL Clevite bearings are the same. They have various "levels". Bogie's description of "internal/external" is right on the money. For those that are still confused about just exactly WHAT IS BALANCING?, here: All pistons are weighed. The lightest one is "matched" by removing material from the others. The rods are weighed, both "ends" and "static". Again, the "light" ones are found and the rest matched. A set of rings (1 piston's worth) is weighed. The rod bearing is weighed. The piston pin and locks (if so equipped). There are two specs: Rotating weight (rod bearing, "big end" of rod, 4 gr. oil) and reciprocating (piston, pin, locks, rings and "little end" of the rod) weight. For most V8s, 1/2 of the reciprocating weight and 100% of the rotating weight are used to calculate the "bob weight". A weight made up to match a PAIR of rod/piston assemblies is attached to each rod journal. If "external", the flywheel/flexplate and balancer are attached. The crankshaft is "spun" by a motor. There are sensors in the stand that detect the "heavy spot" at given RPM intervals. Material is removed or added until the triggers are not activated. If you've ever seen a tire balanced with a strobe light, exactly the same principle. This is a simplification, but accurate. Most modern machines are computer controlled. FWIW Jim |
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We found too many QC issues to suggest the use of Eagle products. And we only suggest selected Scat parts.
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Funny, but this isn't the first time I've heard this about Eagle/Scat. I suppose it depends on what you build, and "how many". The majority of our experience has been with "un-Chevys" (we build about 30 engines per year, more than 1/2 are Pontiacs). We have, however, tried pretty much all the available stuff in the small block circle track applications. (If you wanna know what holds up and what doesn't, circle track is a GREAT "proving grounds"). The Chinese castings consistently "beat out" # 2 and 4 mains.
We have one case where an Eagle 461 "kit" was used in a 400 Pontiac. He put 751 1/4 mile passes and over 3K street miles on it. Consistently "finished" in the top 5 in points at two tracks over a 4 year period, turning 10.30s and .40s, 3.400 lb. '70 Firebird. The one time we tried a Scat 4.25" stroke, we couldn't balance it without adding weight to the leading edge of the counterweight (not good). Others have reported the same issues with the 383/400SB castings (9000 series). We heard about quality issues with the Eagles, but have not seen them. In more than one case, where it was said the crank was "out", the crank was fine and the BLOCK was bad. This falls under the "chicken or the egg" question. Often, crankshafts get "blamed" for problems in an engine when the issues ly elsewhere, the crank being "caught up" in the wreck (so to speak). IMO, if you have something that "works" for you, go ahead and use it. For those that aren't "in the business", sort this out best you can! Neither are "wrong", just different POVs. Jim |
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As said, heard about it, haven't seen it. Perhaps due to it, Eagle fixed the problem? There were a small number of Pontiac castings that "got out" with a rough thrust face. They caught and corrected it. They paid us to repair the ones we found. I KNOW Eagle does try to make things better all the time. As for Scat, well, the balance issue is very real. AND, when one calls a company to talk about a problem, condescention and arrogance are NOT how to win loyalty. One of the highest "ranking" people in Scat told me "SAE AND Sunnen are wrong" about a specific process. The details don't matter. I submit, SAE is THE "final authority" in certain areas, including the one in question. Sunnen supplies the best machine equipment on the planet and has the best trainers for that equipment. No. Scat was wrong.
The "steel" in the Eagle castings is quite different to grind than the factory nodular cranks. I'm NOT a metalurgist, but I can tell the difference in "sound" and finish. Based on the process, I prefer the factory nodulars for anything serious. The bigger-mained (3"-up) cast steel cranks seem to be okay up to 750 HP and about 7,500 RPM. We've used them in Fords and Pontiacs without incident. BBCs do NOT like them at higher revs. FWIW Jim |
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Not sure why we got hung up comparing Eagle VS Scat when all along it should be resolved with this Howards Track Smart 3.75 stroke 5.7 rod hole lighting crank.
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