FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: Mr Woodys Garage on March 30, 2023, 04:29:32 PM
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I'm Looking For Advice And Recommendations For A Machine Shop In The Central US That Can Balance A New Steel 4.25 Stroke Scat Forged Steel Crankshaft, Molnar H Beam Rods, And Mahle 4.160 Forged Pistons, To Perfection. Im Looking For A Shop That Removes The Weight To Obtain Balance By Machining The Counterweights Rather Than Drilling Them Full Of Holes. I Know It Will Cost More, But If The Information, That I'm Basing This On Is Correct, There Should Be Multiple Benefits To Be Gained By Going This Route. I Know That The Common, Quicker Way Of Balancing Is To Drill Huge Holes In The Counterweights. Its Effective, Quick, And Common, But It Just Looks Wrong. This Is A Build That I Want To Be 110% The Absolute Best That I Can Make It. So, Any Preferred Shops That Members Can Direct Me To? Any Help Will Be Appreciated.
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I wouldn't waste your time/money on that. You will never know the difference once the oil pan is on.
In addition, a lot of your aftermarket FE crankshafts will need metal, not metal taken away.
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I agree with Brent, we balance our own crankshafts, I'd worry more about it being done correctly than the means and methods of how they get it in balance. When we're done with one the crank will freewheel for minutes on the balancer. If the heavy metal was placed properly the holes shouldn't be very deep anyhow. Our technique is when placing the heavy metal to slightly overshoot and place the metal slightly higher out than when it truly needs to be, then you can drill a small hole in the counterweight right above it to get it back to balance. You do this because accidentally doing the opposite and under-shooting on weight means you need to add another slug of heavy metal, and that's an uglier end product than the other option.
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Three times a charm
I haven't seen a reciprocating assembly that didn't require something added yet on an FE. In very light combos, light pin, thin ring, dished and Molnar or K1 rods, I have seen only small amounts needed, more on the more standard parts
That being said, one of my two guys has taken counterweights down on a SBF before, then drilled to make final numbers, it worked great, but it was a very light SBF combo not an FE
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Ted Eaton is on this forum occasionally. Eaton Balancing is his business.. He can tell you everything there is to know about crank balancing.. He is in Tx.. but shipping a crank is not hugely expensive. Also Adney Brown in Detroit area has done a lot of FE cranks and is well know in performance circles
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Thank You, Royce. That Was The Kind Of Answer I Am Looking For. There Are Many Ways To Build A "Mousetrap", And As I Come From Old School Thinking About All The Little Things And Details That Add Up, I Need To Be Sure That The Balance Is 100% Right On This Project, As Well As All The Other Details. I Am Still Open To Referals Of Other Shops Or Professionals Who Specialize In This Skill. Im Looking For A Professional That Does This For The Love Of The Craft, Not Necessarily Someone Who Is In It Just For The Money. Thanks To Brent, Ross, And M Brunson For The Ideas And Thoughts On This As Well. I Value Each Of Your Thoughts And Opinions, And Appreciate You Taking The Time To Respond To My Question
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I believe that CWT Balancers have an optional software package that helps determine the OD removal location and diameter for that kind of balancing - but I do not know of any shops that use it. Probably found in very high end stuff - NASCAR and Pro Stock etc. We have cut counterweights down on mill and/or lathe in the past, but it's been for clearance reasons and any balance benefit from a bonus. Most of our FE balance requires localized weight addition and/or subtraction, and moving effective weight from one end of a counterweight to another. Drilled holes and added metal are by far the most cost effective way to accomplish the goal.
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You might give George(Anderson) a call at Gessford Machine shop in Hastings, Nebraska. That's where I get my machine work done and they KNOW Fe motors.
https://www.gessford.com/
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Im Looking For A Shop That Removes The Weight To Obtain Balance By Machining The Counterweights Rather Than Drilling Them Full Of Holes. I Know It Will Cost More, But If The Information, That I'm Basing This On Is Correct, There Should Be Multiple Benefits To Be Gained By Going This Route.
I'm often curious as to others' understandings and beliefs, and perhaps for the benefit of a better understanding for myself and of others could you expand on this as to, other than for "looks", what would you believe to be the "multiple benefits to gained by going this route"?
And yes, I have done many in this fashion in the past. :)
Scott.
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"The counterweight can be drilled in specific spots, or the crankshaft can be turned on a lathe and the counterweight can be cut down to achieve balance. If turning the crank on a lathe is possible, in a lot of ways, it is a better way to remove weight. Cutting removes mass, which changes inertia characteristics. Anytime overall rotational mass can be reduced, it’s beneficial". Copied And Pasted From I Believe Eatons Web Site, Or Scats, I Forget Which.
It Is My Belief That Any Time There Are Holes Drilled In The Counter Weights It Can/Will Weaken The Crank,(After All, Its "Made In China" lol!)(4.25 Forged Steel Scat Crankshaft) And The Holes Create Windage/Drag. I Tend To Strive For The Best That I Can Afford, Which Is Not That Much, But, If Whatever I Build Comes Apart When Im Showing Off, Or Beating It, Then Any Savings In The Cost Of My Build Will Be Minimal In Comparison To The Cost Of An Entire Engine That Explodes Due To Failure Of Inferior Parts, Machining, Or Shortcuts. Im Not Expecting To See Age 70, ( i Am 64 Now) And As I Already Have 8 Years in Building The Car, I Don't Want To Have To Take It Apart Once Its Together. I've Learned So Much From The Contributions Of The Professionals That Contribute To This Forum, For That, I'm Grateful. Thanks To Those Who Share Their Knowledge And Experience.
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How much HP and Rpm are you hunting for? it will cost a small fortune to try and get what your looking for. I could maybe see if you wanted 800hp and was road racing and had a unlimited budget
From what I read of your rotating parts you have good stuff.
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I have been considering this too, have read about folks in the old days doing this with the quite heavy 391 steel crank. I have a 454 setup with light internals, factory internally lightened Arias domes, Crower rods, and with an iron 428 crank, fairly light. I have some pretty good heads and intake so could lean on it and RPM it pretty good. I also have an FE converted 391 crank that was welded and stroked to 3.98 by a well-known skillful crank guy (someone here will recognize this crank) so I was wondering about turning down the outside to lighten it as much as balance would allow, trim up the weight shape a bit etc. I have a 16x60 South Bend, and a Bridgeport so the physical lightening part can happen with my own labor, and my neighbor's machine shop has a good balancer, so I'm thinking take everything in and see how much and where I could cut. I'm sure it would take several trips to the balancer to sneak up on it, then final balance in the normal way. Thinking with some good oiling I could have a pretty solid lower end. Thoughts from the more educated brethren?
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Drilling a few balance holes in a crank will not cause it to come apart or explode, nor will it cause you to have to take anything apart. It's an aesthetics thing, not a strength thing.
In addition, these cranks *need metal*, not need metal taken away. Adding metal also involves drilling holes in the counterweights so that heavy metal can be pressed in.
In specific applications, we cut the counterweights down to reduce weight or help the engine accelerate quicker. However, when you do that, you end up adding a lot more metal.
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Whenever I have sen a broken crankshaft, it has broken where the throw meets the side of the counterweight, and the radius. I can`t say that I have ever seen a crank counterweight break at the outer areas, where any holes would be drilled. Your choice, but to me, seems like a lot of bother to "fix" a problem that doesn`t exist. Factory FE crankshafts have multiple holes drilled into the counterweights, and have proven to be very durable, even in drag racing.
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Well, my interest came because I have a light set of pistons, and though I haven't weighed them, the Crower rods would seem to be lighter than the heavy LeMans units. 454's have been done many times with the iron 428 cranks, which I have a bunch of. The rest of this thing would be capable of some RPM, so the iron crank would seem to be the weakest link, I could just balance it to the 391 crank, but since it has minimal drilling unlike the 427 units, it is one heavy mutha. This was done back in the day before cheap strokers came available, it would depend on how it balanced out, if it needed weight removed, it would be sweet to take some off the outside, especially as I could do that at my free labor. Anyone remember Dan Holmes? He had an ex-Ed Terry Drag Team 68 Mustang with a 447 (std bore) Tunnel Port using the old heavy TRWs, LeMans rods and a welded/stroked 391 crank like mine and a homemade clutch C6 and ran high 9s in the 80s with old-school suspension and not that big tires. One loud sumbitch, too. I was at Fremont one weekend when they had a funny car show, and they had a delay for an oildown. Took a while, then the announcer hollered here we go, and then BOOMBOOMBOOM echoed off that big plywood wall along the staging lanes. The whole crowd got up on their feet to see the funny cars- and Holmes pulled around the corner and lined up- it was that loud
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Just chiming in a again, if dying to try it, I have an old school shop in Omaha that does it but as stated don't expect lightening the crank to solve the heavy metal requirement. Small shop, sharp guy, but wouldn't call it high end, just a good old machinist
Counter-weights "counter the weight" and are designed for a range of expected recip/rotating parts. The fact that FEs need more weight on a minimum of one CW and on heavy assemblies 2, means there isn't enough there now.
However, if you change the request to wanting the lightest possible crank in general, then balance it, there may be some options
Shoot for the lightest rod and piston combo suitable for use, and then go from there
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I Truly Appreciate The Replies And Information I Am Getting On This Question. While I'm Waiting On A Call From Someone I Hope Can Do The Balance On This Project, It Looks Like Help Might Also Be Just A Couple Hours Drive West To Nebraska. This Build Is A Last Hurrah For Me, And Am Trying To Build It The Very Best That I Can, Thanks To All For Bearing With Me While I Get This Important Operation Sorted Out. I Am Aware Of And Have Had To Buy "Heavy Metal" In Engines I Have Built Over The Years, It Was Just A "Give It To The Machine Shop, And It Comes Back, You Pay For It And Move On." This Time, I'm Playing With A Lot More Expensive Crank, Rods And Pistons, As Well As A Pretty Decent Fully Girdled S Scratch 428 Block That I Don't Want To Throw Pieces Out Of When Winding It Up. Yes, Its Equipped With A 3 Qt Accumulator Incorporated Into The Oiling System. Its Going In My 63.5 Galaxie, With A Big In/Big Out Close Ratio "Nascar" Toploader. Im Running 4:30 Gears With 28" Tall Rear Tires. I've Pony'd Up/Saved Up For A Good Set Of Trick Flow Heads, An Expertly Ported And Matched To The Heads Victor EFI Intake,And A Fairly Expensive Solid Roller Setup With Supporting Conical Springs Etc. It Will Turn A Lot Of RPM Just Driving It Normally, Let Alone What Im Wanting To Do With It On A Few Trips To The Drag Strip. So, Balance Is A VERY Important Consideration/Issue To Me In In This Build.
Anyway, According To Summit Racing, Where The Scat Cranks Are Listed, This Forged Steel 4.25 Stroke Crank Is 6 Pounds Heavier Than The Same Stroke Cast Scat Crank. This Is Probably Why A Lot Of The Engine Builds I See With The Forged Cranks Have Holes So Big And Deep In Them That You Could Rent Them Out As Studio Apartments. I'm Sure, That "Operator Experience", Cost, And "Brand Loyalty" Has A Lot To Do With It As Well,. While It Obviously Works, I'm Hoping To Improve On Common Practice.. So, Where Does This 6 Pounds Of Metal Hide Out At? Given Same Rods And Pistons, There Would Surely Be A Big Difference In The Amount Of "Heavy Metal" Needed Between The 2 Cranks. Again, I'm Asking, Because I Do Not Know. If I Could Lose 6 Pounds Of Mass/Weight Off The Crank, (Or At Least Not Have To Add Any To It) The Power Output, Smoothness At Peak RPM, And Lifespan Of All The Rotating And Reciprocating Parts Would Surely Be Noticeable. With The Advances In Balancing Equipment, And Especially The Improvements In Rods, Pistons, Cams And Heads, Making Double The Original Output Of An FE Realistically Obtainable I'm Looking For The Best Possible Combination I Can Get. The Rods Are Forged Molnar H Beams Brent Was Able To Get Ahold Of For Me, And The Pistons Are Mahle Powerpack 1m 1m 2m Forged With 18cc (?) Dish. They Shouldn't Be Extremely Heavy Compared To Stuff That Was Commonly Used 10 Years Ago. So, If You Were Building It For Yourself, With Todays Technology/Options Available, And A Reasonable Budget, (If There Is Such A Thing), Which Route Would You Take/How Would You Do It? Thanks Again For The Help, Opinions, Refferrals, And Discussion On This.
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I think you're a little confused about what does what with regard to balancing these crankshafts.
First of all, the steel crank is heavier because it's steel. There's nothing you can do about that. Just like a factory $, 361, or 391 crank is heavier than a regular 352/390 crank, the modern steel cranks are heavier than the cast ones.
*****If you try to cut 6 lbs off of this crankshaft by just turning down the counterweights, you will most likely open a balancing can of worms**** and there's a very good chance that you will spend literally thousands of dollars to correct it. Lightweight cranks are made by removing metal in other spots, by cutting away the flywheel flange, gun drilling the mains, shaping the counterweights, etc.
If this were a crankshaft that required many, many holes to be drilled in the counterweights to balance it, I could understand the desire to cut the counterweights down. But this is not one of those cases! In order to balance this crankshaft, you may have to ADD METAL TO IT, depending on the bobweight. Cutting the counterweights down will put you in a spot (especially if you're trying to shed multiple pounds) that you will have to add EVEN MORE METAL TO IT. So not only will your balance bill be $$$$$$$ but you will have your crankshaft swiss-cheesed in another direction.
In addition to all of that, if it's balanced, it's balanced. A crankshaft that has had the counterweights turned down to balance it is not any more balanced than a crankshaft that has had holes drilled or metal added. I think in your mind you have an illusion that this is "the better" way of doing things. It's not.
If I were doing this, I would do it the way I do all of them.....choose quality and lightweight parts for the rods and pistons, then just simply balance the crank.
In addition, I personally would not trust a solid roller camshaft to a conical valve spring, especially in a street car, where the springs don't get checked and replaced on regular intervals. I would use a small diameter dual spring with light retainers.
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That Pretty Much Answers My Questions About How To Proceed. Will Have It Done The Way That's Common. I Do Tend To Overthink A Few Things, And This Has Been One Of Them. I Certainly Appreciate All The Input And Advice, And Will Follow It. One Of My Pet Peeves Is When People Ask For Advice, And Then Don't Follow It. I Am Not One Of Those People. Will See If I Can Get This Thing Together By Memorial Day, And Make Some Noise With It. Thanks To Everyone Who Took Time To Help With This,
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I went through my pictures and found one when I was balancing the 4.25" crank for my 428 stroker engine. Hopefully this gives you an idea of what your engine will likely need (being that it's also a 428 stroker engine).
I didn't take any pictures of the drilling operation, but the yellow marker in the picture show where the heavy metal was needed. One piece was put in this location, and then a small hole was drilled in the top of the counterweight to get the balance trimmed back into spec, because we slightly overshoot when placing the heavy metal.
If your situation is similar to this one, which I think it likely will be, only 1 hole will need to be drilled in the top of the counterweight if balanced carefully. You wont have to worry about "swiss cheese".
(https://i.postimg.cc/6pfmX4Lq/IMG-5007.jpg) (https://postimages.org/)
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I think most of the responses have covered the concerns that might be created in an effort to lighten a crankshaft. But if only as a recap: do not just chuck a crank in a lathe and start reducing the counter-weight dimensions, particularly concentric with the crankshaft center-line as even if material removal is required for piston skirt/pin-boss (stroke) clearance with most American V8's it needs to executed in an offset cam-ground fashion to preserve material sums on the counter-weights or you'll be in trouble with the balancing effort. I think that the statement made by Scat, as quoted previously might be based on their origins, that with the VW's flat fours as with these (180° opposing layout) and including vertical in-line fours (Pinto 2.0's & 2.3's these with 180° opposing crank throws for example) it has been popular to cut-down the counter-weights solely to "lighten" the mass. :)
It's not likely that even the poor machining execution of excessive hole drillings in the counter-weights would lead to cracks in the critical areas of the crankshaft that which leads to failures. But I have witnessed cracking happening in cast-iron cranks (rarely) about the machining and migrating in an unpleasant manor that didn't instill a lot of confidence in the unit; but with steel forgings (even those of "off-shore" linage) it would be very doubtful that this would really be an issue. ;)
But in extreme applications of R.P.M.'s , loading and high frequency vibration being imparted to the crankshaft, particularly if the application is known to present greater than appreciated flexibility, it is popular to remove any concerns for the interruptions in even these surfaces presenting windage influences in the crankcase volume (a properly sized (smaller) counter-weight or an oversized one with big holes drilled in it? ::)), and any tooling marks that as unlikely as it may be, may create an issue, and here is where one can justify the reasoning for the "no-hole" balancing efforts (and they "wash-up" easier too! ::)). And all of this is to executed by the one doing the balancing effort! And if this person is capable, this also permits one to better capitalize on the fact that counter-weight values carried nearer to where it really needs to be vs. sums in excess somewhere else attempting the same effect, though the influence is from afar, will prove to be a lesser sum. So although a one hole correction works for the entire mass carried, it's established singular positioning is an averaging of the hole, so is this specifically really where the excess solely is, or just the identified fix? And, it would not be recommended that someone "prepare" a crankshaft with any "lightening" effort, without being aware of the requirements in the balancing first; otherwise as stated previously, you might create quite the challenge for the balancing process, which generally would equate to an enhanced billing sum from the shop for their effort to rectify. :o
Probably the greatest concern is whether the crankshaft as originally created, was this executed properly? As often the manufacturer does not grasp the effect in of the common practice in the use of a singular crankshaft forging with the placement of the counter-weight sums being constant (and hopefully correct for something? ???)and the various crank-pin and bob-weight mass values and placements due to stroke variances. Often this proves to cause the requirement of excessive additions of metal which is being required due not to the fact that there is an insufficient mass sum, it's just not in the right place; so now your crankshaft picks-up weight, to offset the manufacturing errors!
And just to clarify: as far as your steel crankshaft weighing significantly more than the cast iron unit, this has more to do with the sums of material present in the comparison, not the fact of the material differences. I don't know the exact consistencies of the two being compared but some cast irons can be lighter, or can be at least as heavy or more than as some steels, I not sure here if difference would really be significant but......? :-\ As for the 391 steel cranks, my experience in the past is that they come up short on the counter-weight sums and more often require greater heavy-metal additions; this as compared to the O.E.M. 427 cranks.
Overall in something like an FE engine don't get all worked up over the fancified possibilities, as this unit in all but it's rarest forms wouldn't truly benefit from the efforts, and yes "all the details & little things do add up", but just follow sound and proper processes and spend you time and money wisely. :)
Scott.
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I Appreciate That Very Much, Scott. I Will Reach Out To mbrunson427 On Monday, and Schedule A Trip To His Shop. Not Too Far Away, And His Builds Are Very Similar To What I Am Building. I Do Tend To Overthink Things Sometimes, Looking For That Elusive Something That Will Make Average Into Great.
Again, Thanks To Everyone Who Took The Time To Respond To My Question, It Has Been Answered And Explained, So I Won't At Some Point In The Future Wonder"What If?
I Did, Finally This Morning, Take A Good Look At That Crank From Scat. I Had Glanced At It In The Box To Inspect For Shippping Damage, But Not Really Examined The Design Features,How It Was Made and The Quality Level, At Least Appearance Wise. They Really Put A Lot Of Work And Thought Into Many Of The Features. Its Definately Light Years Ahead Of A Stock 428 Crank . Contours, Edges, Etc. Makes The Decision To Upgrade And Spend The $$$ For The Stroker A Bit Easier To Justify.
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Some years ago, I spent significant time in what, at the time, was known as Roush's "Prototype Engineering Facility". I was creating a 14 month series of magazine articles on the right way to build a 21st century FE engine. The prototype shop was the place where Jack was building all his NASCAR engines at the time. Magazines were going through quite a change at the time, so some of the monthly articles were published in Mustang Illustrated. Some were in Mustang and Fords, and some in Super Ford. I had free run of the facility, taking pictures of all the FE stuff necessary to go in the stories. Jack and I had never spoken of it, but on one occasion we were standing talking together and Michael Kranefuss walked in. Jack introduced us and started to tell Kranefuss something. Out of the corner of my eye I could see Kranefuss making motions for Jack to stop talking. Jack gave me one of the very best compliments I've ever had. He told MK that I was to be trusted not to take advantage of anything I might see or hear.
I tell you that so you'll understand that I saw the insides of the NASCAR engines virtually every time I went in there.
The crank balancing procedure at that time was to use a Bridgeport set up specifically to mount a crank so as to be able to bore a hole in the side, not on the circumference, of the crank weight where the balancing machine said it should go. The proper weight of Mallory was pressed into the hole thus formed, and then a fine line of TIG weldment was placed around the circumference of the weight. It looked VERY professionally done. I'm sure that Jack will have no problem with this explanation. I don't know what they do now. The prototype shop is long gone to the Carolinas.
KS
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Some years ago, I spent significant time in what, at the time, was known as Roush's "Prototype Engineering Facility". I was creating a 14 month series of magazine articles on the right way to build a 21st century FE engine. The prototype shop was the place where Jack was building all his NASCAR engines at the time. Magazines were going through quite a change at the time, so some of the monthly articles were published in Mustang Illustrated. Some were in Mustang and Fords, and some in Super Ford. I had free run of the facility, taking pictures of all the FE stuff necessary to go in the stories. Jack and I had never spoken of it, but on one occasion we were standing talking together and Michael Kranefuss walked in. Jack introduced us and started to tell Kranefuss something. Out of the corner of my eye I could see Kranefuss making motions for Jack to stop talking. Jack gave me one of the very best compliments I've ever had. He told MK that I was to be trusted not to take advantage of anything I might see or hear.
I tell you that so you'll understand that I saw the insides of the NASCAR engines virtually every time I went in there.
The crank balancing procedure at that time was to use a Bridgeport set up specifically to mount a crank so as to be able to bore a hole in the side, not on the circumference, of the crank weight where the balancing machine said it should go. The proper weight of Mallory was pressed into the hole thus formed, and then a fine line of TIG weldment was placed around the circumference of the weight. It looked VERY professionally done. I'm sure that Jack will have no problem with this explanation. I don't know what they do now. The prototype shop is long gone to the Carolinas.
KS
That's the way everyone adds metal. Some weld, some don't. If you put it in the outside rim of the counterweight, the engine would promptly introduce the metal to the oil pan (and whatever is underneath).
You didn't see anything secret, that's the only way to add metal.
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That's the way everyone adds metal. Some weld, some don't. If you put it in the outside rim of the counterweight, the engine would promptly introduce the metal to the oil pan (and whatever is underneath).
You didn't see anything secret, that's the only way to add metal.
Now you're getting into the "welding Mallory" debate too?!
We have never welded a piece yet, and have never had a piece come out - but it's only been a couple decades so far. I suppose it couple happen.
But the reality is that you are not going to weld anything to that slug of tungsten (which is what Mallory is). Tungsten is what the darn welding tip in your welding machine is made of because it ain't very easy to weld to. Theoretically, welding a tiny bead around the edge along with a corresponding chamfer in the slug would build a wall around the slug preventing movement. But the simple fact that most folks -including some very high end applications - have been doing without the weld pretty much forever should tel you that it's a "solution looking for a problem".
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We do not weld. Just a press fit. No issues to date, up to 1200 hp and 9000 rpm. I do know some guys who weld though.
My response, “….that’s the only way to add metal” was referring to which axis the metal is installed in.
If you remember “Pop’s” from 8-10 years ago, he tried to install heavy metal perpendicular to the axis of the crank centerline by drilling into the outside of the counterweight. It very quickly made a hole in the oil pan.
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If you are worried about the added weight of the steel crank then just use a Hay's aluminum flywheel. I used then in all my stick car's.
If you have one all ready then disregard this note.
Greg
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We do not weld. Just a press fit. No issues to date, up to 1200 hp and 9000 rpm. I do know some guys who weld though.
My response, “….that’s the only way to add metal” was referring to which axis the metal is installed in.
If you remember “Pop’s” from 8-10 years ago, he tried to install heavy metal perpendicular to the axis of the crank centerline by drilling into the outside of the counterweight. It very quickly made a hole in the oil pan.
Not meant into a dig at you. Just figured we/he was going to go down that path next once it got mentioned.
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O.K., another comment on the Mallory/Tungsten installation processes.
Back a several decades ago it was common to install heavy-metal in the counter-weights perpendicular to the crankshaft centerline, this with a welding process to retain. With proper execution one generally didn't have any problems. But then the generally experienced operating R.P.M.'s kept creeping up, and the process became a more common practice, often by individuals who shouldn't have, and then rather than typically the crankshaft being of steel forgings of the higher-end examples it was being more frequently executed on cheaper cast iron crankshafts which just don't lend themselves to the same interference fitment nor are they as successful to the welding efforts. :)
There are instances where horizontal installations are not reasonably feasible and perpendicular, even if not desired can be performed successfully. Steel cranks really aren't a problem; but yes, if the process is being executed by an idiot, then yes, failure is eminent ::). Now in cast iron, yes that should be avoided; but if it is a must, then I have had no failures (metal gone flying! :o) if really welded in properly. For reference my procedure being: yes, make it a press-in, but not too tight as the iron casting will otherwise crack; position the heavy-metal below the outer circumference of the counter-weight at least 3/8" (more is better but the offset weight value is degraded with depth ;)); Pre-heat the iron cast with the oxi-acetylene torch to a dark glow signature; now with the tig-torch lay the heat to the tungsten (yes it will pool, just takes some amps!) lay down a weld bead on the tungsten and joining the cast iron washing in the parent material onto the tungsten with the filler material which I have found that stainless rod works best. With this not only is the weldment fixturing the metal but the casting above is shrunk reducing the hole diameter. 8)
If done right, and with cooperation from the casting, as it is the cast material that fails and allows the heavy metal to slip, but generally it isn't coming out readily if done right; and I have previously attempted harvesting the tungsten back out of used-up cranks.
Also, yes, solely a press-fit installation (horizontal) does look slick, and yes I have done them that way, but like the previously stated experience that of a professional NASCAR shop where I'm sure they could follow this successfully, they, in such extreme racing requirements, leave little to chance,........... just add the weld material, and the bi@ch ain't going anywhere! ;D
Oh and, If the metal comes flying out, it may exit the crankshaft anywhere in its' 360° rotation! ;) I did see one come out, pass thru the oil pan and bury itself deep in the asphalt, but some others managed to do significant damage to the blocks as they took flight! ::)
Scott.
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I got lucky, RPM steel 3.98 crank, Molnar rods and Mahle pistons required no mallory to balance. Jim
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As a guy who has never balanced a crank, I have a question: If the counterweight counterbalances the reciprocating motion of the pistons and rods, and the pistons and rods in a performance motor are lighter than stock, why do you add weight to the counterweights to balance the crank in a performance build? it would seem that weight would need to be removed to compensate for the lighter reciprocating parts.
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Yes, if the crankshaft in question had been balanced of the same adopted learned procedural calculations process, properly, then if the sum of the revolving and reciprocating weight mass were to be reduced, then the "bob-weight" calculation would be less and yes the counter-weight value in the crankshaft would need to reduced commensurately. ;)
Now note, that in some instances of peculiarity, individuals will stray from the generally recommended and practiced mathematical calculating process to create values other than that considered the norm, but these generally are to address unique scenarios. ???
Scott.
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As a guy who has never balanced a crank, I have a question: If the counterweight counterbalances the reciprocating motion of the pistons and rods, and the pistons and rods in a performance motor are lighter than stock, why do you add weight to the counterweights to balance the crank in a performance build? it would seem that weight would need to be removed to compensate for the lighter reciprocating parts.
Manufacturers design a crank for a specific bobweight. Sometimes the bobweight doesn't match the parts that are available. Also, some cranks are designed for external balance and then guys go and internally balance them.
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As a guy who has never balanced a crank, I have a question: If the counterweight counterbalances the reciprocating motion of the pistons and rods, and the pistons and rods in a performance motor are lighter than stock, why do you add weight to the counterweights to balance the crank in a performance build? it would seem that weight would need to be removed to compensate for the lighter reciprocating parts.
Often the H-beam rod and bigger bolts, etc weigh more than factory parts, or the crank isn't designed to be balanced the way you try to balance it (like internally balancing a 428)
I have a 390 crank I ran in my Mustang years ago that we added some weld back in the 90s on one throw. Designed for a 390, we had some big TRW slugs and had to make it up. Yesterday, a factory balanced 427 crank took a little Mallory, with Diamond 4.25 with a slight dish, and SCAT H-beam, wasn't much but the rods are pretty heavy, which drove a small add. Both of those were heavier components. Hate to do it, but for the combo and budget was right.
Assuming your scenario of lower reciprocating and rotating weight dropped with new parts, I'd expect that any properly balanced crank would need drilling, not added weight as you describe.
Haven't done a before and after with lighter parts on one that was already balanced though, but you have it right
ON EDIT: Brent is spot on with the target bob weight, I just did a 6-71 blown SBC with a lightweight internally balanced crank, That crank came with documentation for the intended bobweight. We couldn't get there with the combo we were using, although it was close, so it also took a little Mallory. If I would have used a rod and piston combo that met the numbers, it likely would have balanced without weight. Our "less expensive" FE cranks don't advertise a desired bobweight, but I did one with Molnar rods and a 17cc dish and it took very little Mallory, less than any I have seen before