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what should i use 6 inch or 5.7 rods?

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Old May 13, 2005 | 09:29 PM
  #1  
91RS5speed's Avatar
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Joined: Sep 2002
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From: Duluth, Ga
Car: 91 RS
Engine: 305 TPI
Transmission: T56
Axle/Gears: Auburn Pro / 3.42
what should i use 6 inch or 5.7 rods?

not sure what to use on my 383 do you get more power with longer rods? i would think the longer rods would be heavyer and wouldnt rev as well?
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Old May 13, 2005 | 10:28 PM
  #2  
TheMysticWizard's Avatar
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From: San Lorenzo, California
Car: 1987 Firebird Trans AM
Engine: 383 TPI...very soon
Transmission: TH700R4
I heard that when building a 383, if you use 6" rods it puts the wrist pin pretty close or in the bottom ring grove. I have also heard that the difference between the two rods is so minimal, that you're better off going with a 5.7" rod and not having the wrist pin so high up on the piston.

Makes sense to me, I went with 5.7" rods.

I could understand if you want to get a crank that will balance internally, I believe they all need 6" rods. Then your engine would appear as a regular internal balance 350 from the outside. If that matters to you at all.

I'm interested to see if anyone else has anything to say about it also...
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Old May 14, 2005 | 02:57 AM
  #3  
rgarcia63's Avatar
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Joined: Jan 2003
Posts: 2,133
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From: Houston, Texas
Car: 88' IROCZ
Engine: 388 TPI Motown 350 Race block
Transmission: 700R4
Axle/Gears: 2.77
I used the 6" because the rod/crank ratio is closer to stock than the 5.7s.

5.7"/3.48" = 1.6379 stock 350
6.0"/3.75" = 1.6000 stroked 383
5.7"/3.75" = 1.5200 " "
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Old May 14, 2005 | 08:42 AM
  #4  
hot68's Avatar
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Joined: Nov 2004
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From: TX
Car: 68
Engine: 383
Transmission: homebuilt 4l60
you can internally balance with either rod but its easier and cost less to balance internally with 6" rods because it generaly wont require heavy metal balancing. There is negilble difference powerwise between the 2.
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Old May 14, 2005 | 09:21 PM
  #5  
91RS5speed's Avatar
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Joined: Sep 2002
Posts: 330
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From: Duluth, Ga
Car: 91 RS
Engine: 305 TPI
Transmission: T56
Axle/Gears: Auburn Pro / 3.42
If I wanted to boost or run nitrous what would be better?
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Old May 15, 2005 | 11:19 AM
  #6  
1989GTATransAm's Avatar
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From: Cypress, California
Car: 1989 GTA
Engine: 369 TPI
Transmission: 4L60E
Axle/Gears: 3.70 Nine Bolt
I would use what costs the least. Like was said above powerwise there won't be any difference.
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Old May 15, 2005 | 02:00 PM
  #7  
doc's Avatar
doc
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Joined: Jul 1999
Posts: 2,149
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From: Mims, Florida
Car: '87 IROCZ
Engine: 395 ZZ4
Transmission: ProBuilt 700R4
Axle/Gears: 9 bolt 3.70s
You do have a third option, several rod companies have 5.85" rods which work with 383s or 395s. I used this rod in my 395 because I did not want the wrist pin so high up in the piston (in the ring grooves). Trick Flow and Eagle have these rods.

BTW: it is not the rod length that anything to do with power. You should be talking about crank throw instead, AKA, long stroke VS short stroke.
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