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View Poll Results: What should a build focus on?
Crank
9.52%
Pistons
66.67%
Rods
23.81%
Voters: 21. You may not vote on this poll

Building a motor, which is more important?

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Old Apr 19, 2006 | 03:32 PM
  #1  
Token's Avatar
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From: Toledo, OH
Car: 1992 Firebird
Engine: forged 357
Transmission: 700r4, 2200-2400 stall, vette servo
Axle/Gears: stock pegleg 2.73 drum (temp)
Building a motor, which is more important?

Obviously they all are important, but what would you focus on?

Looking at a 383 street car, ~400hp and under 10:1 c/r with a peak RPM of 6000.
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Old Apr 19, 2006 | 05:54 PM
  #2  
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From: Calgary, AB, Canada
Car: 1982 Trans-Am
Engine: 355 w/ ported 416s
Transmission: T10, hurst shifter
Axle/Gears: 10 bolt, true-trac, 3.73
i'm guessing you mean, if you only had the cash to upgrade one, which would it be? then i'm saying pistons.

crank and rods effect strength mostly, pistons do that too, but also effect compression ratio and flame travel and therefore some engine characteristics, more than the others, so pistons should be focused most on.
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Old Apr 19, 2006 | 06:03 PM
  #3  
ME Leigh's Avatar
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From: Valley of the Sun
Car: 82 Z28
Engine: Al LT1 headed LG4 305
Transmission: TH350
Axle/Gears: 3.73 posi with spacer
I would worry the least about the crank. But good rod bolts are very important. You also might as well go with cap screw rods to eliminate any cam contact problems.
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Old Apr 19, 2006 | 06:34 PM
  #4  
Token's Avatar
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From: Toledo, OH
Car: 1992 Firebird
Engine: forged 357
Transmission: 700r4, 2200-2400 stall, vette servo
Axle/Gears: stock pegleg 2.73 drum (temp)
You can take a cast crank pretty damn far. I've really never heard of people breaking a crankshaft, but I have personally blown out a few rods in my day.
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Old Apr 19, 2006 | 07:32 PM
  #5  
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From: GO PACK GO
Car: 83Z28 HO
Engine: Magnacharged Dart Little M 408
Transmission: G Force 5 speed
Axle/Gears: Moser 9" w/Detroit Trutrac
I think all 3 are important, so I didn't vote. Everything depends on what condition the stock crank and rods are in....

-But you already knew that.....
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Old Apr 19, 2006 | 08:58 PM
  #6  
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From: Ohio, near columbus
Car: 89 iroc-z
Engine: 305tpi
Transmission: wc-t5
Axle/Gears: 10 bolt 3.08 posi (4 now)
if i had to build my engine around 1 part it would be camshaft selection myself but, outa those 3 i'd say at your level pistons also.
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Old Apr 19, 2006 | 10:57 PM
  #7  
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IHI
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From: Waterloo, Iowa
Car: 86 firebird with 98 firebird interi
Engine: pump gas 427sbc Dart Lil M 13.5:1
Transmission: Oldani TH400 w/ BTE 9" convertor
Axle/Gears: 31 spline Moser/full spool/4.11Rich
Stock crank, R&R rods with ARP rod bolts, then stick your money in the slugs if you want to stick your money anywhere in the bottom end. The stock iron will take alot of abuse...been there
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Old Apr 22, 2006 | 09:03 PM
  #8  
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From: old bridge new jersey
Car: 84 firebird
Engine: 434ci
Transmission: turbo 400 3500 stall transbrake
Axle/Gears: 10 bolt 4.10 spool'd
in my car the most important parts were compression,cam,stall converter,gears and tire size
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Old Apr 22, 2006 | 09:08 PM
  #9  
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From: E.B.F. TN
Car: Tree Huggers
Engine: Do Not
Transmission: Appreciate Me.
You mean there's no choice for machine work? Of the three available, for the application stated, I don't think there is any other choice but pistons.
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Old Apr 22, 2006 | 09:18 PM
  #10  
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From: MD
Car: '88 IROC-Z medium orange metallic
Engine: L98
Transmission: 700R4
Axle/Gears: 3.27
That's a retarded question. And very broad at that. In terms of durability, the rods take the most abuse. That is, of course, unless the motor is out of tune. Then the pistons will take the abuse of detonation etc. Think about it, you've got a piston traveling up the cylinder, building momentum the whole way. Then all of a sudden the crank tries to change the direction of the rod/piston. All of the momentum now has to change it's direction and move back down the cylinder. Guess what takes all the abuse? Those two tiny little rod bolts. But like I said, if it's detonating, the pistons are going to take a beating as they try to push the crank out the bottom of the block.

To answer your question you should focus the build on the bottom end as a whole. Set out a plan and follow it. If you plan to build an n/a 383 with 10.1:1, do that and don't spray it 6 months down the road. If you want to spray it, build accordingly. And keep it in your budget. If you get yourself stretched too thin and start to cut corners then you're going to end up doing it twice.
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Old Apr 24, 2006 | 08:42 PM
  #11  
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From: GA
Car: '90 C1500
Engine: SBC MPFI
Transmission: 4L80e
Axle/Gears: 4.30
I put pistons b/c one piston slap will drive you crazy(ask me how I know) and two with a forged piston, you can't really hurt it with nos or anything.
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Old Apr 24, 2006 | 08:59 PM
  #12  
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From: Brighton, CO
Car: '72 Chevy Nova
Engine: Solid roller 355
Transmission: TH350
Axle/Gears: 8.5" 10-bolt 3.73 Posi
dialed in is a smart man.
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Old Apr 24, 2006 | 10:11 PM
  #13  
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From: E.B.F. TN
Car: Tree Huggers
Engine: Do Not
Transmission: Appreciate Me.
Dialed in has to put what he reads in context:

Originally Posted by Token
Obviously they all are important, but what would you focus on?

Looking at a 383 street car, ~400hp and under 10:1 c/r with a peak RPM of 6000.
Since Token has been on for a while and has participated a good amount in the gen tech area instead of the appearance board, one can safely assume he has at least a grasp of the concepts that have been covered countless times. That said, in that context, with the limitations he presented, you can'y make a recommendation? He's not asking what part to blow money to the detriment of the other components, he's asking in a roundabout way which should be at the top of his list. I'd personally rather see machine work at the top.
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Old Nov 2, 2006 | 10:05 AM
  #14  
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From: Louisville, Ky
Car: 1991 Z28
Engine: 383
Transmission: T-5
Axle/Gears: 3.08 10 Bolt
Right up with machine work I'd vote for cleanliness! Mic, polish, and clean the crank. Shot peen the rods and add some ARP hardware. Then get new forged slugs and go to town! With 'only' 400hp you could probably use hypereutectic pistons as long as you aren't going to spray it.
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