Crankshaft Balance
Thread Starter
Instructor
Joined: Feb 2005
Posts: 207
Likes: 13
From: Belmont California
Crankshaft Balance
I have a new 427 crank with a target bob weight of 2350g. My calculated bob weight is 2474g. If the target is correct, would you have to drill the crank flyweights or add Mallory metal?
I'm only asking because I got the crank back from the shop and I don't see any fresh drill marks or welded holes.
I'm only asking because I got the crank back from the shop and I don't see any fresh drill marks or welded holes.
Race Director
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From: Corsicana, Tx
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They'll need to add some weight. Either Mallory or weld up some of the drilled holes. Can you swap pistons or piston pins to something lighter?
JIM
JIM
Burning Brakes
Joined: Dec 2003
Posts: 1,150
Likes: 154
if thats a stock crank you have (6223) it may be for a 396 engine.G.M. used that no# for both engines,the difference being the third counter weight on the 427 is wider,7/8" for the427 and 7/16" for the 396"
Thread Starter
Instructor
Joined: Feb 2005
Posts: 207
Likes: 13
From: Belmont California
I was told it was balanced right out of the box and they didn't have to do anything. I'm bringing it back tomorrow to make sure. The end flyweights are 1-1/4" all the others are 3/4". It is an Eagle 4340.
There is more to the story but I'm not going to flame the machine shop...
There is more to the story but I'm not going to flame the machine shop...
Racer
Joined: Jan 2015
Posts: 293
Likes: 43
From: Vernon B.C.
Any crank that I`ve sent out for balance has always had welding or drilling done to it. I balance the pistons and rods and then send one piston, wristpin, rod, rod bearings and ring pack along with the crank, balancer and flexplate (flywheel) and let the balance shop do their thing. Never had a problem and as I said, their is always evidence that its been worked on. Even with Eagle and Scat rotating assemblies that have been balanced still need some tweaking. I guess it could depend on how fussy the shop is. If they say no one will know then id walk away because you will know. Just my .002 cents....
