6-71 pulling balancer off motor!
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Car: 91 S10
6-71 pulling balancer off motor!
ok im asking this question for a friend of mine...
he has a 49 chevy truck, with a 327 and 6-71, it has 10:1 compression, i have no clue as far as timing, it has aluminum heads (he wont tell me what kind, or specs, but i suspect AFR) the thing runs wonderfully on 7lbs of boost, running 12.6's - 12.7's (at 5300 ft) but twice now he has put his 12 lb pullys on and both times half way down the track the entire balancer flew off.... the first time he assumed it was because the 327 crank didn't have the center bolt from the balancer to the crank, its only press on, and it sheared the keyway... so he ordered a new crank with the bolt in the center, well on the second run it happened again, i dont know if it stripped the bolt out or just broke it in half or what, but it did give out, and sheared the keyway again.... he's thinking it just because of the resistance trying to spin the blower that fast and that he just needs a dual keyway crank... but i think he definately has a problem what are your thoughts?
BTW i know that 12 lbs non intercooled boost, and 10:1 compression will scare a lot of you, but he is using race gas, and he says there is no audible detonation
this is becoming a very expensive problem seeing as how everytime it does this it destroys his lower pully, belt, balancer (fluidamper) and crank
he has a 49 chevy truck, with a 327 and 6-71, it has 10:1 compression, i have no clue as far as timing, it has aluminum heads (he wont tell me what kind, or specs, but i suspect AFR) the thing runs wonderfully on 7lbs of boost, running 12.6's - 12.7's (at 5300 ft) but twice now he has put his 12 lb pullys on and both times half way down the track the entire balancer flew off.... the first time he assumed it was because the 327 crank didn't have the center bolt from the balancer to the crank, its only press on, and it sheared the keyway... so he ordered a new crank with the bolt in the center, well on the second run it happened again, i dont know if it stripped the bolt out or just broke it in half or what, but it did give out, and sheared the keyway again.... he's thinking it just because of the resistance trying to spin the blower that fast and that he just needs a dual keyway crank... but i think he definately has a problem what are your thoughts?
BTW i know that 12 lbs non intercooled boost, and 10:1 compression will scare a lot of you, but he is using race gas, and he says there is no audible detonation
this is becoming a very expensive problem seeing as how everytime it does this it destroys his lower pully, belt, balancer (fluidamper) and crank
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From: Western Ky
Car: Z/28..39 Plymouth truck in progress
Engine: S/B
Transmission: Manual
I am running 9 lbs on a B&M Mega Charger which has a little more displacement than the "GMC" 6-71's. I only have one keyway and have not had any problems but I do know that they recommend the dual keyways
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Dude get him to double key a real hub on that thing. I would never use a big 6-71 with a "balancer/damper unless its a ati. Either buy a ATI made for blowers or get a Dyers or BDS blower hub and have the crank double keyed.
I had my crank double keyed to run 33% overdrive using a dyers hub.
I had my crank double keyed to run 33% overdrive using a dyers hub.
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Originally posted by 614Streets
Dude get him to double key a real hub on that thing. I would never use a big 6-71 with a "balancer/damper unless its a ati. Either buy a ATI made for blowers or get a Dyers or BDS blower hub and have the crank double keyed.
I had my crank double keyed to run 33% overdrive using a dyers hub.
Dude get him to double key a real hub on that thing. I would never use a big 6-71 with a "balancer/damper unless its a ati. Either buy a ATI made for blowers or get a Dyers or BDS blower hub and have the crank double keyed.
I had my crank double keyed to run 33% overdrive using a dyers hub.
i could be wrong about the fluidamper... i know he had one of those before the blower... if it helps it is the complete kit from holley, out of summit... i dont know if the kit comes with a hub like your talking bout or not, but it is single keyway right now, he already plans on getting the dual keyway so that should help
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Originally posted by stevedave454
i could be wrong about the fluidamper... i know he had one of those before the blower... if it helps it is the complete kit from holley, out of summit... i dont know if the kit comes with a hub like your talking bout or not, but it is single keyway right now, he already plans on getting the dual keyway so that should help
i could be wrong about the fluidamper... i know he had one of those before the blower... if it helps it is the complete kit from holley, out of summit... i dont know if the kit comes with a hub like your talking bout or not, but it is single keyway right now, he already plans on getting the dual keyway so that should help
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