Join Date: Mar 2004
Location: Snohomish, Washington
Re: Have a lead on 68 big block
A 454 with a 396 crankshaft displaces 427 cubes; but the crankshaft has the wrong counter weights for the bob-weight of the larger diameter bore 427 piston.
The 396 crankshaft is the same as the 427 crankshaft in stroke and journal size, but the counterweight design differs. The third counterweight on a 396 crankshaft is 3/4" wide, and with a 427 it is 7/8" wide. If you use a 396 with standard weight pistons you will need some Malory metal to balance the rotating assembly.
You could use longer rods to lighten the pistons by changing the compression height, and have them lightened even further in the machine shop, but it will cost more in labor; plus you are now buying eight rods as well as eight pistons. Better to buy a 496 rotating assembly from Scat and just run 350 horse 396 decals.
I did just about like Dave is describing with my 447 BBC. Used a 3.76 stroke Callies crank with 496 pistons and 6.635 inch rods. Came to within 0.005" of the stock deck height that way. The balance guy did have to lighten the crank a little to get it to balance, drilled a pretty healthy hole in both front and rear counterweights. The engine runs real well with the large bore and short stroke, revs almost like a small block.
1967 Camaro 427 BBC, Viper T-56 6-Spd, Z28, Red w/ White Stripes
No, it's not stock.
No, it's not real.
No, it's not for sale.
It's just the way I like it.
1998 Camaro Z28, Daily Driver