double keyways on crank?

[79centurion]

Do you need to have double keyways on the crank for a blower? Weiand says that their blower are setup for a stock harmonic balancer, so that means only one keyway. Others say you need two keyways. I am putting on a blower in the 8-71 to 14-71. I am thinking 14-71 so I can upgrade at a latter date. I will underdrive it around 20% to achive 10lbs of boost on my 396. What can happen if I only run one keyway? Will it just destroy the keyway? I dont want to take the bottom end apart at this time.
Dan

[Infomaniac]

I've been there done that. I did'nt want to disassemble mine and double key the crank. It sheared off the key, trashed the balancer and the crank had to be repaired.
Don't do it mon
Do you need to have double keyways on the crank for a blower? Weiand says that their blower are setup for a stock harmonic balancer, so that means only one keyway. Others say you need two keyways. I am putting on a blower in the 8-71 to 14-71. I am thinking 14-71 so I can upgrade at a latter date. I will underdrive it around 20% to achive 10lbs of boost on my 396. What can happen if I only run one keyway? Will it just destroy the keyway? I dont want to take the bottom end apart at this time.
Dan

[Schiada76]

Check my sheared pulley bolts thread.
Double key the crank for sure, use an ATI blower dampner and make sure you through bolt the six bolts. The Weiand v-pulley doesn't fit the ATI locating pilot correctly it's about .125 off, you'll need a bushing made and you'll have to drill the six mounting holes all the way through the v-pulley or buy one with six holes and the correct pilot hole.

[79centurion]

http://www.kenlowe.com.au/99344-01001.htm shows that they recommend only one keyway. "The KEN LOWE RACE CARS supercharger drive hub comes with only one 1/4" keyway. We can supply double keyways if so desired. We feel it is not necessary as the accurate indexing between the keyways is difficult and as such usually on of the keys takes the most load anyhow. The removal of extra metal on the hub and the crankshaft makes both of these weaker as well. For these reasons almost all Top Alcohol Dragster and Funny Cars do not use dual keyways now."
I would really hate pulling this thing apart to do double keyways. Can you do it with the crank in the engine, if so how, or can someone help me?
Dan

[Havasu47]

We would NEVER turn a blower with one keyway, especially a 14-71. Any qualified machine shop can accurately install the second keyway. I personally don't know of any way to do it without removing the crank.
Now with that being said...I should add that we, and many others, install Whipples on 500's and 525's without adding the keyway, but I also dont believe the Whipple requires as much torque to turn as a 14-71.....

[79centurion]

I may just go back with my original plan with a f1 procharger with a cog belt setup. I just dont want to pull it apart right now. I am going to build another motor in the near future, and if I pull this one apart, it would be a waste of money. This motor was just put together at the begining of the season.
Dan

[Schiada76]

You would only need a 6 on the 396 so it would probably live with the single keyway if you're underdriving it.

[MAXIMUS]

I am pretty sure that I am running a single key way on my motor with a 1471. But then again I am only spinning it 13% under at appox 6700 rpm. However 7100 has come about from time to time! :220v:

[79centurion]

I am looking to underdrive it 20-25% with the 396. I know a 6 or 8 would work, but dont want to buy another one in a year or two when I want to go bigger. This way I can just change a pulley or two. With this motor, I wont see over 6,000 rpms. The boat N/A is seeing 5,000 rpms with a A impeller. Maximus, is there any way you can easily check if you are only running one keyway, and how long have you had that setup?
Dan

[gn7]

I am pretty sure that I am running a single key way on my motor with a 1471. But then again I am only spinning it 13% under at appox 6700 rpm. However 7100 has come about from time to time! :220v:
yeah there you go maxi, run over here to blower motors and spread your b.s. around about how your running 1 key about half the proper lenght, stock damper, ace hardware bolts on a 14 and it works great, yeah yeah yeah.