I have an older balanced assembly for a 455. I am getting new steel rods and pistons. If I weigh the new rods and pistons and make them all the same would I have to rebalance? If the old rods and pistons were 1400grams and the new stuff was 1200grams it should not make a difference. The crank was balanced with 1400gram bob weights and now would be balanced with 1200gram weights. If the crank is balanced it should not matter what bob weight you hang from it as long as they are all the same and it should be balanced, no? Thanks ...Eric.

I have an older balanced assembly for a 455. I am getting new steel rods and pistons. If I weigh the new rods and pistons and make them all the same would I have to rebalance? If the old rods and pistons were 1400grams and the new stuff was 1200grams it should not make a difference. The crank was balanced with 1400gram bob weights and now would be balanced with 1200gram weights. If the crank is balanced it should not matter what bob weight you hang from it as long as they are all the same and it should be balanced, no? Thanks ...Eric.

I'm no expert but it seems to me the crank throws would have to be lightened for the lighter rods and pistons.....

Bob weight is Rotating weight X 2 (total of one throw) plus the reciprocating weight. If you change any weights, the bob weight will need to be adjusted. http://forums.performanceyears.com/g...icon_frown.gif

Just got a case of re-balance blues.

Since the new Ross pistons will be lighter than the old TRWs, I figure that perfectly balanced rotating assy is gonna schwing a tad heavy in the counterweight.

You bet I'm a gonna weigh a TRW then a Ross. to know what the gram(s) difference is.

Hmmm, wonder if I can just drill-out the front and rear holes that got weight welded in...I got a drill and some masonry drillbits. Knowingly gotta remove excess mass from 180degrees away from the throw. Question is do I remove twice the piston grams or 4x ?

Half-In balance Stud

"11.00/123MPH/1.50 60foot/29.5"/4.10:1/10"/472 #48/Flat HYD/DualQuad/Wenzler/3250Lbs
12.00/112MPH/1.61 60foot/26"/3.31:1/10"/472 #48/FlatHYD/Q-Jet/Torker/3650Lbs
12.70/103MPH/1.71 60foot/28"/4.10:1/12"/472 #48/FlatHYD/Q-Jet/Torker/3950Lbs"

Thanks guys, I'm not trying to be cheap, it's just that here in the Great White North I have to ship it out! That's about a 5 week wait if I'm lucky. By the way, just before I fired up the Caprice this morning I looked at the thermometer and all I saw was a red ball! -39 C that's -40 F! I guess the heads in the back of my truck are Cryo'd now! Thanks ... Eric.

A one percent over balance would be fine. On higher rpm engines I over balance often.

Is there someone on this board that actually balances crank & recipros for a living?

"11.00/123MPH/1.50 60foot/29.5"/4.10:1/10"/472 #48/Flat HYD/DualQuad/Wenzler/3250Lbs
12.00/112MPH/1.61 60foot/26"/3.31:1/10"/472 #48/FlatHYD/Q-Jet/Torker/3650Lbs
12.70/103MPH/1.71 60foot/28"/4.10:1/12"/472 #48/FlatHYD/Q-Jet/Torker/3950Lbs"