Which is better? 4340 or 5140

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Dec 10, 2002 | 08:33 PM

94-6spd

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Joined: Oct 1999

Posts: 1,112

Likes: 1

From: W. Kentucky

Car: 83 Z-28

Engine: 406

Transmission: TH350

Axle/Gears: 3.70

Which is better? 4340 or 5140

Which is the better metal for a crank? 4340 or 5140

Dec 10, 2002 | 08:41 PM

jcb999

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Joined: Aug 1999

Posts: 1,443

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From: College Station, Tex USA

Car: 89rs

Engine: 400Sb

Transmission: Tremec 3550

4340 steel is the best

everything else is less than perfect. 4130s then 5140 is the quality of steel.

Dec 10, 2002 | 08:45 PM

AlkyIROC

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Joined: Jul 1999

Posts: 17,262

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From: 51°N 114°W, 3500'

Car: 87 IROC L98

Engine: 588 Alcohol BBC

Transmission: Powerglide

Axle/Gears: Ford 9"/31 spline spool/4.86

4340 is the best.

Both are a Chrome Moly steel.
4340 is lighter
5140 has better corrosion resistance

http://www.scatcrankshafts.com/newslawone02.html

Dec 10, 2002 | 10:02 PM

94-6spd

Thread Starter

Supreme Member

Joined: Oct 1999

Posts: 1,112

Likes: 1

From: W. Kentucky

Car: 83 Z-28

Engine: 406

Transmission: TH350

Axle/Gears: 3.70

Thanks guys. Great link Stephen 87 IROC! Very informative.

Dec 10, 2002 | 10:37 PM

94-6spd

Thread Starter

Supreme Member

Joined: Oct 1999

Posts: 1,112

Likes: 1

From: W. Kentucky

Car: 83 Z-28

Engine: 406

Transmission: TH350

Axle/Gears: 3.70

O.K. I have another question. How much power can a nodular iron crank handle?

Dec 10, 2002 | 11:05 PM

AlkyIROC

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Joined: Jul 1999

Posts: 17,262

Likes: 168

From: 51°N 114°W, 3500'

Car: 87 IROC L98

Engine: 588 Alcohol BBC

Transmission: Powerglide

Axle/Gears: Ford 9"/31 spline spool/4.86

I'm assuming this is in a SBC.

A stock cast crank can easily take over 550 HP. There are a few prepped stock cranks that reach 700 hp. A nodular crank is stronger and can survive most buildups.

I've run a stock cast crank in my engine for the last few years. I just upgraded to a 4340 crank to reduce some weight.