Balancing ?

[Jerry Millington]

Ok you put everything (per rod) on the scale
and get all your #s.
Then do you grind metal from rod to get
the same?
Where on the rod?
jerry

[Greg Moss]

send it to some one that knows what to do. It is cheaper to get it done than to buy a new rod because you screwed one up. Don't know how much Jay gets to do them he did the last set I had done. I can do them but it is time consumong and tedious work. something better to be left to someone set up to do it. A new top guided rod is $250 do you want to take that chance?

[Jay Smith]

Jerry ,

We do at least 2 to 3 sets a week it is $150.00 + freight and like Greg told you , you don't want to do this job. We use a 7 step abrasion method and its not rocket science BUT to buy the protective masks. suction hoods, grinders, porting tools , abrasion rolls , pads, buffers with 4 different roughes, and scales it's user unfriendly to do it ! 1 day turnover, some things are an easy and a do it yourselfer managleable task this AIN"T one of em...........


Also as Greg said gotta know how much to take off and where also get em too hot ,toss em you ruin the heat treat, grind marks in em too deep with the cross cut , toss em the harmonics will run up the rod stop at the cross cuts and they break take off too much in one place , toss em they will break. Some folks say its an easy do it yourselfer , I say if it done correctly and the end result gives you a lighter , stronger rod , its not for most folks !
Again your motor your choice but for $150.00 why take the chance , I haven't had a rod break yet with an estimated 150 sets ( 900 rods ) successfully completed and used in some of the top Hi HP motors in and out of the country. Your choice......


My opinion,

[Techno]

Wasn't mentioned but the rods aren't just made the same wieght. The big ends are wieghed and made the same, The small ends are wieghed and made the same. The rod end is put into a fixture so the rest of the rod is weighed. Pivots like. So along with the gram scale you would need a nice pivoter to take both sized ends.

[jerry]

techno , have you done alot of these jobs ?

[Techno]

Not a single one.
It was posted before, by pete.
I'm repeat.

The other post showed how he had one end on the scale while the other was in a thing, fixture to hold it. This weighed only one end of the rod.

The search didn't find it. Probably not back far enough.

[hydrostream1]

I`ve seen a guy at my local machine shop balance rods and pistons for an automotive engine,he weighs each rod and piston on a digital gram scale,from what i saw he took the lightest piston weight then matched the heavier pistons by grinding some from under the crown or side of the piston to match the weight of the light piston.then he did the rods the same way.The automotive rods have a weight at the big end to grind some material off of.the outboard rods do not.I guess from what jerry was saying do you guys grind then polish the side beam of the rod to equal the light rod?Just asking some questions,don`t mean to sound like a idiot or know it all,just here to learn.

[Tom D.]

Thee old hinee hairs stickin up on that one!:eek:

Tom:D

[Simon]

Techno is right. I do alot of balancing.

[Jay Smith]

Did that guy that was into the 3 litre rebuild call you ? I gave him your and Marles number he was looking for a builder in the area.....

[Simon]

Yes he called, Thank you for the referal.

[Jay Smith]

My pleasure..........

[hydrostream1]

Could anyone explain the piston and rod balancing process?(hopefully without smartass remarks)like i said here to learn.

[BenKeith]

First you need scales that read fraction of grams.

Then you devise a hanger for the big end so rod is approx level with little end setting in center of scales. Find the lightest little end and make all little ends that weight. Use medium grit stone for rough cut the fine got get marks out then use veryfine and then buff. All the time being very careful not to get it hot. Do not cross cut with grinder.

Next weigh the whole rod and find the lightest, go through the same process as with the little end takeing metal off big end and get all rods weighing the same. If the big end has enough metal.

Shot peen the rods twice after finishing.

Some builders only balance total weight on two stroke motors, and I've never known anyone that had a problem doing this.

Pistons are weighed and all are brought down to the lightest one. The weight come out of the bottom of the crown and NOT of the skirts. Knowing where you can and can't take metal from is what you learn after they come appart inside the motor at 7K - 8K rpm.

Same with the rods. When the wristpin hole or big end pulls out and goes through the block lets you know not to take as much off nest time or to polish and shot peen better next time.

Now with all that said, it's reallly a lot cheaper to have it done by someone that knows the limits and where to get the metal from and how much to get.

A professionally preped rod will be better and much stronger than anything you could ever hope to do yourself.

Matter of fact, go to post on PISTON ARTWORK. You can see how JSR lightend and polished the beams on that rod. Notice how smooth and shiney. That rod will be stronger than a factory rod because I can assure you, it's done right.

[hydrostream1]

Thank you mr.keith,very informative post,just curious as to how it is done and will probably send the rods and pistons to jay smith,as soon as i can come up with the dough.