blueprinting question for builders....

[green67cuda]

I was measuring my rods last night and have a few questions. how close do they need to be, for one.....mine are all within .8 gram

and then...i made up a jig for measuring the big end, and they are all within .8 grams. I can then assume, that since i measured all the big ends exactly the same way that the small ends are also within a gram, right?

after I file the rings I can use weights of the pistons and bearings to keep everything equal, right (like the lightest pistons with the heaviest rods)???

then...does the machine shop need to know the weights by big end/small end (rotating/reciprocating), or just the total rod, bearing, piston, pin, and ring weight?

 

[moper]

step 1, match all rods to the lightest, if possible (like you have done) match the ends respectively, but that can really be a pain.
step 2, match all pistons to the lightest.
your balancer guy will need the weights of the bearing, the rings, the big end, and the small end, and will figure the bobweight, then spin the crank. A competition balance job is within .5g where I go. Some shops' balance jobs are as far as 10g off, and no balancing is much more than that. Nice work BTW...Its very important to do the steps you're doing, or paying to have them done..you can notice the difference in the end product.

 

[green67cuda]

so they can't jst use the total weight of all the parts? I was going to give them the total weight so i can assemble the pistons to the rods and whatnot while the crank is being balanced

 

[moper]

no, because the whole rod isnt rotating...IIRC, it's the big end, plus 1/2 the small end they need, but I'd just give them both measurements. (balancing is something I pay for, I dont do it myself..So it's been a while since I asked about it. Assembling the pitons and rods take a few minutes...It's more important to get the weights right and get those numbers to the shop.