Originally Posted by
jerry clayton
edit---I did go start to read the Harley write up and it is totally wrong for a V8 auto engine----the v twins are nowhere near the same running /balance requirements as the automotive engines, so disregard everything that artical says.
I won't take the time to read the harley link but will explain the numbers on the balance card.
On a 90* V8, you have 2 rod/piston assys on each crank journal. The weight for the bob weight is made up of the TOTAL of wt of 2 BE(big end) of the rod s plus 2 bearings, this weight is arrived at by supporting the SE(small end) of the rod and weighing the big end. So that is how they got ROTATING WT 1329---663+663+3= 1329-----------RECIPERCATING wt is total of only ONE SE ROD, PISTON ASSY(piston,pin,rings,locks) as the 90* offsets the other one ---SOOOO the Bob Wt is total of ONE piston,pin,rings,locks,SE rod plus weight of 2 BE rod ,2 (4 halves) bearing inserts and an allowance for oil weight.
Then with the 4 bob weights made up, one is attached to each crank rod journal and the balance job goes forward from there--
I will try to take some pics of one of the balance jobs I will be doing this week and try to post them---if I end up with both internal and an external weighted crank I'll try to show some differances--of course then there are the internal front/external rear cranks from GM LT1/4 engines???????????????