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21 Daytona
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Discussion Starter #1
Should I cut dual keyways in my crank?
1053 steel 4.00 stroke with a M3 Procharger
I know it wont have the load that a roots type blower would have
so whats the most common configuration? 3/16 and 1/4 @ 180°?
I plan on running an ATI balancer/damper
 

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Should I cut dual keyways in my crank?
1053 steel 4.00 stroke with a M3 Procharger
I know it wont have the load that a roots type blower would have
so whats the most common configuration? 3/16 and 1/4 @ 180°?
I plan on running an ATI balancer/damper
i say yes most definetly...i would use 1/4", full length slot & square allen stock for the key :)...this is what i ran on my blown SBC ages ago lol...just my .02 cents :)

FastRat
 

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Dual Keyway

It is not needed on a BBC, except in the most extreme cases. The SBC has a problem with balancers lasting. Adding another keyway helps, but doesn't address the problem. There is very little material from the corner of the keyway to the seal surface. This is where they break. ATI offers 2 different hubs for their balancers. The first one adds 35% more material from the corner of the keyway to the seal surface. This will work with a stock timing cover and only requires a special seal. The second one adds 225% more material. It now has a BBC o.d. This requires a special timing cover for the SBC because it now has a BBC seal. It is pretty stout.
 

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steelcomp was here
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yes BBC, so I dont need to worry about cutting the second keyway?
You can go with a single 1/4" keyway and be safe. It's a PITA to have two keyways line up perfectly. A lot easier for a machinist to broach a new one in 1/4 and be done w/ it.
 

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21 Daytona
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Discussion Starter #6
I just got a reply from ATI, they suggested thier part # 917740
it has a 3/16 keyway in the stock location and a 1/4 @180°
they can also drill it for 6 pulley mounting holes on a 3.200 bolt circle.

my machine shop said no problem cutting the second keyway.

Procharger suggested a second keyway over 10 psi boost
I'm setup for 8

I thought the 6 bolt circle would be a good idea since I will be running a
crank trigger wheel between the balancer and blower pulley.

is this overkill? good insurance? or a waste of time?
 

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Some guy
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3,610 Posts
I just got a reply from ATI, they suggested thier part # 917740
it has a 3/16 keyway in the stock location and a 1/4 @180°
they can also drill it for 6 pulley mounting holes on a 3.200 bolt circle.

my machine shop said no problem cutting the second keyway.

Procharger suggested a second keyway over 10 psi boost
I'm setup for 8

I thought the 6 bolt circle would be a good idea since I will be running a
crank trigger wheel between the balancer and blower pulley.

is this overkill? good insurance? or a waste of time?
For the small amount it costs to have the 2nd key at 180 degrees, don't even give it a 2nd thought, do it and have the piece of mind. A decent machinist can get it right. My engine balancer does them for me, never had a problem with one lining up.

The 6 bolt balancer is also the way to go.
 

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I just got a reply from ATI, they suggested thier part # 917740
it has a 3/16 keyway in the stock location and a 1/4 @180°
they can also drill it for 6 pulley mounting holes on a 3.200 bolt circle.

my machine shop said no problem cutting the second keyway.

Procharger suggested a second keyway over 10 psi boost
I'm setup for 8

I thought the 6 bolt circle would be a good idea since I will be running a
crank trigger wheel between the balancer and blower pulley.

is this overkill? good insurance? or a waste of time?
Thats the balancer I bought, came with 2 slots had the crank done, end of story, not absolutely nesc, but why not????
 

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"It's HONDO, honey"
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cheap insurance for gulling up the end of a perfectly fine crank and then tearing it ALL down, mine cost 200 and bergeron cut the dampner as well
 

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steelcomp was here
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For the small amount it costs to have the 2nd key at 180 degrees, don't even give it a 2nd thought, do it and have the piece of mind. A decent machinist can get it right. My engine balancer does them for me, never had a problem with one lining up.

The 6 bolt balancer is also the way to go.
Won't argue with that....

cheap insurance for gulling up the end of a perfectly fine crank and then tearing it ALL down, mine cost 200 and bergeron cut the dampner as well
...or that.
 

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"It's HONDO, honey"
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"It's HONDO, honey"
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Thanks for the confirmation, It will be done....:)devil
:D K you got me..... wanted to up my post #, did it again :D:D:D:D:D


:)hand
 

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yes BBC, so I dont need to worry about cutting the second keyway?
You don't NEED to.
You also don't NEED to wear a condom when picking up a hooker in the bad section of town. But it is a good idea!
HaHa :D
Sorry..couldn't resist.
Wags
(still laughing)
 

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"It's HONDO, honey"
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I tell you what just put lock tite red on the crank's shaft hil:) never mind the 1/4 keyway. Hell just tack weld it on :D:D:D not really funny cause I've seen it
 

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Gone
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Not sure about the condom but I have run single 1/4" key on every blown motor I have ever built and never had a problem.
Just when you had your mind made up. LOL>
 

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I'm famous !
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Not sure about the condom but I have run single 1/4" key on every blown motor I have ever built and never had a problem.
Just when you had your mind made up. LOL>
Ya but you never let toney drive :D as Mrs clever said -- He's been a little hard on the beaver ....... :D
 

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OK, I know some guys that only run a single 3/16 key on their roots blown big boat stuff. In all honesty, I have only seen 1 balancer shear the key and spin. It happened to be an external balanced piece. Ity damn near shook the drag hydro off the trailer at idle. I laughed my ass off.
So, one failure..tons of success...
Wags
 
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