mountainmagic

to run a 6-71 blower is it really required to have a double keyed crank?
engine is a 383sbc
eagle 4340 crank
balancer is pro products sfi balancer

weiand says they highly recomend having a double key crank. i have ran the engine on a dyno with a 6-71 @ 14* and it didnt break. i just cant see myself taking the crank back out to get it cut for a 2nd key.

has anyone had experience with this?

kp

iTrader: (34)

I would do it if you are going to beat on the car, street cruiser you may be able to get away with it if the balancer has a tight interference fit.

mountainmagic

the balancer is tight.
i do have a HEAVY right foot
can a regular auto machine shop do it or do i need to send it somewhere special?

kp

iTrader: (34)

Just about any auto machine shop can do it, bad part about it is if it shears you will tear the crank up and it has to come out anyhow.

mountainmagic

yeah i guess your right
prolly shoulda done a bit more research

Jimmy P

iTrader: (177)

I had mine pinned,and it ended up snapping the pin and ruining the snout of the crank. I had to order a new crank, tear the motor apart, etc. It is getting a double key way this time.

njc.corp

get it done--if u know u have a heavy foot-

or risk the damaged and twice the $$$ later on-

get it done and over-

markb1234

Plz do double key ur crank. On the 4th of july i got to experience what happens when the crank hub spins off. An ounce of prevention is worth a pound of repair. Im just now getting my crank pulled. Bran new eagle crank which is now garbage. I havent ordered a new one yet, but im getting ready to call eagle and buy a double keyed crank. I bought an ati bbc double slotted crank hub, new ati super damper, $298 timing cover to accomodate the bigger hub, and a new spacer to line up my pulleys correctly. My hub was actually spinning to a point, for quite some time. I caught it when the pulleys started to go out of line and the power steering started slipping in and out. But It was too late the stock hub took way too much material off my crank snout. U live and learn i guess, but this lesson cost me some loot. So save urself some money and get it double keyed.

93formto98T/A

iTrader: (28)

x2 I was running an F2 with 50mm cog belt. I had a lunati proseries crank with single key and it sheared off on the dyno under partial throttle tuning. I didn't even get to make a WOT pull.

What you need is a SBC crank w/BBC snout and dual keyways. Anything less and you'll be pulling the motor frequently for new cranks. The amount of sideload blowers place on the cranksnout and bearings is tremendous.

HUGGER ORANGE SS

iTrader: (2)

Plan on running alot of power? I would recommend double keying. We double keyed our recent project car. Whipple Blown 377LS3 17psi boost. 811 / 805 RWTQ.

Zero issues.

Clint