balance
Thread Starter
Teching In
Joined: Mar 2005
Posts: 36
Likes: 0
From: alkoor
balance i have a question
my cranckshaft bob white 1800g
my piston and pin 620 g
insert 45 g
big end 394 g
small end 151 g
oil 4 g
locks 11 g
total bob weight 1690 g
why do the crankshaft do i need the balance or not the balance
thanks
my cranckshaft bob white 1800g
my piston and pin 620 g
insert 45 g
big end 394 g
small end 151 g
oil 4 g
locks 11 g
total bob weight 1690 g
why do the crankshaft do i need the balance or not the balance
thanks
TECH Resident
Joined: Apr 2008
Posts: 828
Likes: 12
From: Right here, right now!
There is a formula to work out what the influence of the big end and small end have in terms of the actual bob weight to be applied to the crank for balancing purposes.
As I am on my 3rd glass of wine, I cant remember where to locate the details, so will defer to someone who is more on the ball.....
And might drop in here and comment. 
hic......... My apologies. 
FormerVendor
Joined: Dec 2005
Posts: 250
Likes: 1
You have to also include the ring set weights. From the post It looks like someone has calculated a bobweight of 1690 G's, because the weights given wouldn't work out to that when allowing for reciprocating vs. rotating weights. If the 1690 g bobweight is correct and the crank is balanced at 1800 grams then yes you should balance it. I like to add a few percent for stability in high HP engines when we balance, but that's way off.
