Well by mix and matching my CP pistons and Crower rods, I was able to get the four assemblies pretty close to each other.

But two of the assemblies need a little bit of material removed because the CP pistons don't come weight matched as well as the Crowers. So my question is, what part of the piston do I take material off of?

It's not going to be alot. Each piston rod assembly should weigh 708.6g and two of them weigh 708.9g so I just need to remove 0.3g from two of the pistons.

 

Well I guess I shouldn't have made the assumption that all the crower bolts were the same weight. Turns out (for some reason) that four of them weighed 17.7g and four of them weighed 17.5g.

So I did some more math and reorganized everything so now all the piston/rod assemblies are exactly 708.8g.

I'm the ******* man

 

Just so you know,the rods are balanced on each end.All the crank ends are the same and all the wrist pin ends are the same,not just the total weight.Not a big deal on an inline for,but important on a v6 or 8.
Glenn

 

What happened is that I pulled the rods out of a 400whp turbo z6. I kept all the rods matched with their corresponding caps. I figure that whoever built the motor before me had them weight matched already.

So yesterday when I weight matched all the assemblies, I kept the rods paired up with their original caps. Hopefully that keeps things as balanced as possible.

Although, I doubt if any of this really matters anyway because we're only talking about a few tenths of a gram. And like you said, with an inline four, it's not that big of a deal. But since I have a Benson crank, I wanted to balance the assemblies as best I could since I already paid for the crank to be balanced.

But since I already have this thread in the archives (and because I'm curious), where are you supposed to remove material from the pistons?

 

The rods have to be kept with their original caps because they are machined as sets.Material should be removed around the wrist pin bosses for balancing.
Glenn

 

Is the material removed by drilling or filing?

 

Is the material removed by drilling or filing?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hondahatch741 &raquo;</TD></TR><TR><TD CLASS="quote">Is the material removed by drilling or filing?

</TD></TR></TABLE>

It matters how much and the shape/size of the bosses.Most modern performance pistons are so close I normally use a porting tool.
Glenn

 

400whp on a d16...wow

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by methos713 &raquo;</TD></TR><TR><TD CLASS="quote">400whp on a d16...wow </TD></TR></TABLE>

That's basically what I'm shooting for on this build too. Except it's a y8 now and it's not sleeved

 

if i remeber correctly, the machine shop that balanced my motor said that it was off withing 2 grams?? he said that it was not that big of a deal, though he balaced it anyways...

im sure you're ok with your differences...

 

Yeah, most after market rod and piston manufacturers already match their sets to within a few grams. I just wanted to get it to a tenth of a gram because I already got the crank balanced, so I figured what the hell...


So you're not supposed to switch rods and caps? I kind of figured that the rod/cap sets were align honed from the factory (common sense) but I was reading an engine building thread somewhere where they said to mix and match rods/caps to get the big ends balanced to each other. I didn't risk it though.