Andrew89tpi

Is there a way to tell if a crank belongs in a 305 or 350? I ask because I bought a crank kit from an engine building place, and on the sheet they list it as 305/350. I bought it for a 305. This is pretty confusing to me now.

89IrocZ350TPI

I thought the 305 and the 350 used the same crank.

Mkos1980

iTrader: (8)

The balance. There is a way but I dont know if off the top of my head. i heard you can put a stright edge along the counter weights and if they are = its this and if not its this. Dont know which one though.

Apeiron

Counterweights are larger on the stock 350 crank to offset the heavier pistons. The straight edge will lay flat on the 305 crank, but not the 350.

On an aftermarket crank it doesn't really matter, but you'll probably need more material removed to balance it in a 305.

sofakingdom

iTrader: (1)

Exactly.... they start out life as the same casting, but then are machined differently, for the different balance weight required.

The 305 has the balance weights that a straight edge doesn't lay on.

Apeiron

Are you sure it isn't the other way around?

Mkos1980

iTrader: (8)

From reading lingenfelters book it says "A 305 crank will allow the straightedge to lay flat across all five points. A 350 crank will not allow the straightedge to sit flat."

1989GTATransAm

iTrader: (3)

So if you are using light weight pistons and rods in a 350 it maybe better to use a 305 crank for balancing purposes if I read the post correctly.

sofakingdom

iTrader: (1)

Sorry....

Apeiron

If you're changing weights of the components, it's best to just have it balanced. It doesn't matter what crank you start with, but it's easier to take weight off a crank than it is to put it back on, so the heavier crank is preferred.