Balancing

[TTriton]

I'm once again rebuilding a engine. This time I plan to play a little more with the rebuild. One thing I plan to address is balancing. I understand all about how to do it exept where should I remove metal from? Should I remove metal from the rods or from the pistons or from both? And where from on them. Thanks.

[Jay Smith]

Don't know how others do it but I machine weight, approx 30 grams, off the piston and widen and deepen the transfer window also I use my modified wrist pins that remove from 107 grams stock core to 74 modified. Also important we remove as much as 30 grams from the Hi Per "small rods" and 60 off the larger Hi Per (1991-1994 and the 2000-2001 drag and S 300 models) you remove the cast flashing off the side of the rod BUT you can only remove the metal in the direction of the harmonic path not ladderly , if you remove metal in the oppisite direction of the harmonic path the vibration will travel up the lenth of the rod hit the cut in the metal and will have a tendendency to break. Also we polish the beams to chrome.Quite alot of work if you don't have the proper tool and machines. We have packages in our web site and after you get half way into this project you may have second thoughts about this being a do it yourselfer. :)
http://www.jaysmithracing.com

Good luck,
Jay @ JSRE

[Raceman]

Jay, if the rod is to be polished, does it still matter in which direction the metal is removed? Also, is shot peening helpful in any of these rods? I'm not turnin my stuff hard enough to matter, but I've still been thinking about a pro 120 motor from a bunch of old parts. Also, do you weigh/balance the individual ends of the rods?

[Jay Smith]

We still do all cuts with the grain running paralell even the polishing process if you look at the grain under magnification you can still see the way the abrasion is cut. Also most of the rods we balance ( about 5 sets a week ) we are only finding about 1 out of 25 rods where the end cap is VERY heavy and need to be cut. The closer to the center of the axes of rotation the more the weight is negated. The further "out" on the rod the more criticle we find it! Pistons , rods, and wrist pins are balances to "O" gram differences. All 6 of the assemlbies are "on the nut" as to balance we take ALLOT of time to insure this tolerence.

I have balanced motors and the customers commented how much smoother the motor even idles.I can remember on a Land and Sea ad they claimed that for every 1000 rpms the out of balance condition squares. ( example if a combo rod,piston. and wrist pin is 9 grams out @ 1K @ 2K tt is 81 grams @ 3K it is 6561 out and so on.)I have seen Hi Per motors straight from the factory be as much as 45 grams out from the lightest to the heaviest .
Hope I've answered your question!

Jay @ JSRE 1 281 576 5088 CST

[racer]

I agree with Jay that the direction of the rod polishing is very critical and the piston, rod, pin and bearing assembly are all that should be touched. I do however feel that total rod weight and big end rod weight should also be matched, this is VERY time consuming. Shot beaning also helps to stress relieve the rod. This policy I find to work with ALL outboard motors.

[MadMat]

I understand polishing parts that are subjected to tensile loads reduces areas of stress concentration, and also that shot peening works to harden the surface of the material. But do you shot peen before or after polising?
Surely if you shot peen AFTER polishing, your are increasing the roughness of the materia, thereby adding sharps edges which will concentrate stress again.
But it you shot peen BEFORE polishing, surely the polishing process will remove much of the material that was hardened by the shot peening.

Please can someone clear this up for me, it's had me confused for ages.
M

[Rickracer]

I personally shotpeen after polishing. Polishing removes stress risers, but shotpeening doesn't really create any. When I sent the rods for my small block Chevy in to be shotpeened, they looked so good, the shop called me back to warn me they wouldn't be so pretty when they got done.(Apparently folks who saw them kept asking who made them (Chevy X rods)).I told em I didn't care, nobody was gonna see them after they were installed, LOL.

[TTriton]

As with any technical endeavor there is always more questions to ask and more knowledge to learn but I've got the gist of it. But just to let you know I would buy a video in a second that taught this to me. Maybe one for balancing, lighting, and polishing of the rods and another one for port and polish of the blocks. Here's a way to make some money that I'm sure many of us here would glady pay for. They wouldn't even have to be professially edited just hand someone a camcorder and have another narrate what is going on. Make it a first relase here over scream and fly save up a couple bucks then have it pro done with Beta camera's and editing then sell them over the net and in ads in mags like hot boat. I know someone made a good profit down here with a stupid video on how to catch lobsters so I know that this can be done.

[TTriton]

Now that I have dust all over me I'm taking a break. I have the rods done. I matched them all to 350g and polished the beams of the rods. That was easy expecially since I didn't need to remove all that much material to match them. Now for the pistons and wrist pins. All the pistons are very close but when I got my wrist pins they sent me 3 from one source and 3 from another sourse and there 15 grams diffent from one another. So where should I remove metal from? How do I lighten the wrist pins? Or should I remove the metal from the pistons? And from what jay said I think I understand where to take the metal from on the pistons but if there is any way someone could e-mail me a picture of a lighted piston or I can e-mail a picture of a stock piston and have some one make notes on the picture. I don't mean to sound stupid but I just want to make sure I remove the right metal and not set myself up for a major problem.

[Jay Smith]

Lee,
Page me @ 1 713 833 9223 and I'll call you !
Right now 9:00 CST 9-1-01

Jay @ JSRE

[MadMat]

Lee/Jay,
I think this is something many of us would be interested in, could either of you e-mail me some pictures and I'll chuck them on my website so everyone can use them for future reference. Obviously I will give credit and links to your own sites.
M

[Edited by MadMat on 09-02-2001 at 08:27 AM]

[TTriton]

Pictures from me might be lead some one in the wrong direction. But some pics from a pro like Jay or some other pro's would be great. Maybe get several differnt howto galleries of pictures showing differnt technics.

[FCnLa]

I thought shot peening reduces surface stress caused by the forging, reducing the chance of fracturing. It increases surface hardness?:confused:

[Rickracer]

Yes, it does increase surface hardness. You can use it for many things too. for instance, springs last much longer when shot peened before use. Some of what I have read/studied about suggests that cryo treatment can add strength too, but I've never tried any of that yet.

[nitewolf]

so is it a good idea to balance the rods even up so that the little ends are the same and the big ends are the same as the others? and that they are all the same weight do you use some kind of fixture to REST the side your not weighing on ?and as far as the pistons go are we taking the weight off the inside under the crown? also the rods as far as finishing them am i to ASSume were sanding and polishing lengthwise with the rods? what about COMPRESSION BALANCING when ya make all the cylinders the same volumn.

[Talon2.5]

well for the average guy to balance a piston and rod in his garage if he reeeeeeeaaaaaly wants to try it, and not mind that it wont be in any way as superior a job as jays could!! but doing it in this manner, which by the way did make the motor smoother at an idle and didnt break any rods or pistons.....dont thrash me too bad here guys but it worked on a zero budget and stood the test of time and WOT (time was 3 summers it ultimately blew up because of a piece of plastic sucked in through the air horn and lodged in the reeds on #5, WOT was 7000+)is really by no means the "right" way to do it!!

tools: commercial tabletop disk/belt sander (like i said dont thrash me too bad), two digital gram scales, scotchbrite air gun with the brown 3m disk, die grinder with fine fluted carbide cutter in the acorn shape, and a head porting set with fine sandpaper rolls, on the belt sander where the belt wraps around the wheel is the surface you want to use, in this case it was a 4inch diameter wheel and a five inch wide belt and i believe it was actually a wood shop type of machine, trust me this is only if you reeeeeaaaally want to give it a shot and dont mind being shadetree about it and dont mind probably spending more money in the end!!!

by this is gonna get me in trouble, i can see it coming.

with the pistons and rods seperated, wiegh the pistons and use the lightest one as the weight to go for, if you desire less wieght take it from this one first, take as little as posible from the wrist pin boss to retain strength using the carbide bit, take out the casting flash around the transfer port openings and the wristpin bosses, smooth out the large holes in the pistons on a 2.4
and 2.0 flowing the holes in toward the inside of the piston at an angle improving fuel flow to a minute degree, open the smaller hole thats not drilled into the wrist pin area, this will also help remove the wieght and improve flow to the finger port, when youve done what you wanted to achieve in wieght smooth it out with the fine sand paper roll in the porting kit, match the rest in the same way trying to match the flow on each one as well as the weight.

was that a gun i heard cock? dont shoot me yet!!

wiegh the rods and again use the lightest rod as the one to go by, by the way the belt should be around 220 grit on the sander, using the wheel surface of the belt, sand the casting flash of the rod beam sanding long ways from wrist pin to crank end without sanding the wrist pin area or the crank area strictly the beam, sand it smooth to the point of no casting flash being to prominent or to the point of being the same wieght as the lightest rod doing it slowly, smoothly and constantly checking it on the gram scale to compare wieght, once in the ballpark of the desired wieght, leaving quite a few grams to go, put the rod on two gram scales, the wrist pin end on one, and the crank end on another oh ya make the light rod your using,to the desired wieght in this way first that your using as a wieght guide using the scotch brite gun with the brown pad polish the rod taking out the sand marks and polish the wrist pin end as well as the rod cap with the scotchbrite to match the wieghts of the rod your using as a guide, the scotch brite brown pad will remove more meat than you think it will so be aware of what your doing, make each rod weigh the same at the wrist pin end and the crank end the same as your "guide rod" if the guide rod shows 40 grams on the wrist pin and 70 grams on the crank end then make them all the same in this manner, the weight of the "guide rod" should be matched "to the gram" on each rod following.

so in the begining record the overall wieght of the "guide" rod using a single scale,do the necissary work to obtain your desired wieght and record the "overall" wieght then record the weights of the wrist pin end and the crank end with the rod resting on the two gram scales at the same time trying to keep the ends of the rod as much in the center of each scale as possible with out the scales touching each other, and make them all the same.

then if ya want to in a sense, shot peen em you can use a class bead cabinet masking of all surfaces that the bearings come in contact with including the factory smooth sides that ride on the crank and the sides the washers that go on the wrist pin area and the oil slot on the crank end, or just wrap the ends totally leaving only the beam area exposed, using masking tape or duct tape and make sure the tape is in resiliant shape throughout the process replacing it as necissary.

ok is that shadetree enough for the do it yourselfer? bear in mind i posted this with full intention to prove that jay and alike are the men for the job and you can get yourself in deep sheot this way in a real hurry, this really is a machine shop process but if your intense on causing your self grief thats the way to do it!!


yes i did do it like this, and i did it another way that i wont post due to this being embarrasing enough to admit, it did work but isnt the right way at all to do it with any professionalism, or even any attention to metalergy (sp)?

later,

the man to get thrashed, skip

due to the graphic nature of this procedure
we suggest you dont try this at home :eek:

[Rickracer]

I am no expert, but making everything weigh the same, be as strong molecularly as possible, and have the same volume "generally" is the idea. That's the "blueprinting" part. I say generally, because pulse tuning, which is kind of a black art to me, is definitely a part of making more power too.

[nitewolf]

Talon HEY sounds like a winter project to me! is the scotchbrite gun you mentioned earlier a dynofile with the thin belt? why do ya have to have two scales? wouldnt one digital scale work as long as ya didnt bump it while you were weighing the parts in conjunction with a small stand off to the side of the scale with a roller bearing to rest the I.D.wouldnt this locate close enough and have the repeatability one would need to get the job done? ive messed with a scale i bought recently and it didnt matter where i put the weight on the scale this baby repeated the same reading every time i could hang a cigeratte off the side and it would still PICK it up. :p Rickracer on the compression balancing i was thinking this would help i mean it couldnt hurt...id have to round up some equipment though but at least that kind of stuff dosent cost an arm and a leg,this is a interesting thread id like to see some input from the BIG SHOTS on the procedure they use to weigh thier rods ...see ya Nitewolf

[Talon2.5]

nite wolf if ya read jays post, he did explain to an extent about the end caps being heavy, if you have one scale you can weigh the rod but all your gonna do is make them all weigh the same, which is the general idea but you need to have two scales to do a "weigh in" of the rod ends.

if ya have one scale and put the rod on you get as an example "120 grams" you can make all the rods wiegh 120 grams, no problem.

but with two scales side by side you can "tune in" the rod ends because even though they all wiegh the same the ends dont, ya see what i'm getting at? it's in jays post on the first page.

the scotchbrite gun is a 90 dgree die grinder with a scotchbrite pad attachment that is a 2 inch diameter screw in pad that ya buy off the snapon truck, it's a pnuematic (air) hand tool.

the best thing to do is have multiples of the same rods and weigh them all and take the rods that are closest to each other because iv'e seen them vary in wieght dramatically.

trust me if i did it again it would be bought through someone like jays shop it's a long tedious project and ya cant get as good a job at home as they do with there machines, really !!


i had one rod i couldnt get to match the others and had to find a new one in my stash of parts to make a set that would work, these were the 2.4 big rods, and besides that when your all done ya have to weigh the piston and rods all assembled and they all have to match in wieght with wrist pins, needle bearings and the wrist pin washers coming into play through the whole thing, i suppose if your snowed in for 6 months and have a basement full of tools you could give it a shot, but you have to have an understanding of metal and the grains also posted by jay on the first page.

i have to admit it was fun "playing" with it but the final out come was not as professional as a machine shop will do.


later, skip

[Techno]

Are the rods cast or forged?
And would it be worth the trouble machining them out of a chunk of aluminum? I have the tools for that but not the patience or expertise. Just curious.

For the single balance thing, If you put one end on a fulcrum and the other on the scale you'll get a different reading than if you just over hang the object. This is an idea I still have to test for wieghing the boat/trailer.
Using a board weigh the trailer/boat. Then do just the trailer when you've splashed the boat. where the tire sits on the board, the board sits on a fulcrum, and on the scale allows you to use a reguler 300lb. scale. I can use a truck scale but I don't like leaving my boat to go weigh the trailer.

[Jay Smith]

The Mercury Rods are a casting that 's what the ugly cast flashing are on the sides of them. An Aluminum rod would be an unlikley canidate in a needle bearing application as it must have a hardened incert for the needle bearings to ride ( 65 rockwell hard ), most car motors that use alum rods use babbot bearings and can use them because the babbot is a buffer between the alum material of the rod and the forged steel crankshaft which is hollow and oil is pumped tru it and tru mating holes in the rod to feed the bearing with pressured oil the oil pressure creates a cushion of oil that the surfaces, in theory, don't touch ! .

Good luck and good boating !
Jay @ JSRE

[Rickracer]

I have used the method you suggested for a few sets of rods, and it does work. I made a fixture to suspend a small roller bearing just above and off to the side of the scale. I checked my work repeatedly, and always came up with the same numbers. This setup was described to me by a great machinist, so I made one to suit my needs, and it served my purpose quite well. The scale I was using was an electronic paint scale, accurate to a tenth of a gram. I see that Jeg's, (www.jegs.com,)has some scales made for this purpose in their catalog now.

[nitewolf]

:D I can see i didnt word somthing correctly somewhere ,RICK RACER picked up on it though sorry for the confusion guys i shoulda used the term suspend,rest,fulcrum,pivot somthin""" thats what i was gettin at one half of the rod will rest on a fixture and the other will rest on the scale that would be adjustable up and down or just figure out where ya need to put two holes in it and set it up on the ole bridgeport to keep the rod level i think that would make a difference as far as the almn rods go you can harden it but your not gonna get even close to the hardness that one would need. I myself will not sacrifice performance for reliability if ya cant FINISH a race what good is it?also if ya had a digital scale thats only good within 2 tenths(will only read a 2 tenths difference) and ya wanted to get a little more precise of a gram one could have a xtra weight of 1 tenth and set this on the scale along with the end your weighing and itll get ya within 1 tenth of a gram instead of two tenths .

[Rickracer]

...but most automotive machining is done to half a gram anyway, and that's pretty darn close. :-):cool:

[Talon2.5]

i understood what you said with the standoff and one scale but i dont believe in doing it that way, i like the two scales for total accuracy but as ive seen writen on this board "whatever floats your boat"



later, skip

[tombrown]

Talon, do you have any idea the number of hours the balance job took you to complete? If not, could you take a wild guess. I know these things take way longer than they ought to.


Thanks,

Tom Brown

[Rickracer]

Not to answer for Skip, but I had about 1 1/2 to 2 hours in each rod de-flashing and polishing, and about 1/2 an hour to an hour each balancing. :cool:

[Talon2.5]

ya ricks pretty close i think i had 4 hours a rod, but it was mostly in the balance end of it due to getting to the knats ass and one of the rods i could not get in close enough and had to use another rod all together ;)

[Jay Smith]

WOW,
24 hrs to balance 6 rods, Maybe I should go up on our $150.00 a set charge. LOL........... 1 Day turn over time . We do on an average of 5 sets a week.

Jay @ JSRE

[nitewolf]

Talon nothing wrong with the 2 scale deal XCEPT i only have one scale hmmm time to get off the BIG BUCKS and buy another one OR SOMTHING (J smith)good comeback and a little advertising at the same time I liked that J.

[Rickracer]

It should be easy to see that your prices are a bargain, especially with the world famous quality of your work. :cool:

[Talon2.5]

it would have been a hell of alot eisier to have jay do 'em thats for sure!!

oh ya.....jay can ya do the pins in a set of 2.5 mahles that i have that fell out? you know the good pin style you do!!

later skip

[Jay Smith]

Skip ,
We can do your pins no problem . Standard 2.5 weisco WP 107 gram JSRE pin 74 grams .... Malhie 2.5 pin 98 grams JSRE pin 70 Grams $ 200 .00 a set with your cores. 2 week turnover.

Jay @ JSRE

[Talon2.5]

and also the pins that hold the rings in place?


later skip