balancing

thank you john w,dave and gary let me ask somthing i forgot how important is it to balance the engine?what is actual done and who does this type of work? thanks to all enjoy your weekend steve

Your local machine shop will do it!! They basically spin up the parts like a tire and balance it all! You will see little marks where they have ground off a little bit here and there on rods, pistons and flywheels! That is called 'Dynamic Balancing'. Years ago, they just used to way up all parts and make them the same weight, that was called 'Static Balancing'! To get a four cylinder engine dynamically balanced is $198 cdn in Victoria, or the equivilent of $150 usd. Well worth the money!!

Before they dynamically balance it, a good machine shop will balance each piston to the others, baalance each rod to the others & ensure those combinations are the same weight before they start spinning anything...actually, they don't hook the rod/piston combination up to the spinning crank, they put weights on it to replicate them...so, its important that the rods are balanced end-to-end & the pistons balanced one to another to get that weight!

Tony, you ever balanced rods? How is it done? I know one end is on a scale and the other is supported, but is the rod level with the bench or is it inclined to transfer the weight to the low end? I've matched rods, matched pistons, matched rods and pistons together, shot peened rods and rockers, and polished them both. turn counterweights off on motorcycle cranks to lighten them, but never tried to balance rods.

Gerry:

Balancing rods end-to-end is a good idea, that way the moving masses are all balanced. It really doesn't matter if the rod is horizontal, as long as each rod is EXACTLY the same! Personally, I would keep them as near horizontal as possible and use total weight as a sanity check. Be careful how and where you remove material - you do not want to add any stress risers to your rods!

I agree...horizontal is the only way I've seen it done...& removing excess metal is almost an art - you have to take it off so it doesn't afftect rod's strength....taking metal off pistons is easy, just go up inside them & carve away