Eagle Forged Crank
01-06-2002, 11:50 AM
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Eagle Forged Crank
Where is the cheapest place to get an Eagle forged crank for a 350? I know definately not summit or jegs. Also, whats the difference between 4130 and 4340 steel. I know one is stronger, but what other aspects are diferent and how much stronger is 4340?
01-08-2002, 01:43 PM
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Car: 1986 Z28
Engine: 355
Transmission: th400
i'm not sure wht summit or jegs charge, but the machine shop got mine for 400 bucks.
the differnce in 4130/4340 is the type of steel and the how it was forged.
4340 is a tougher steel, but generally not used on street motors because of the tolerances needed.
one of the things that make them stronger are the radia on the crank. wider the radia at the journals, the stronger the crank.
the 4130/4340 both have wide radia, with the 4340 being stronger,with a wider radia.
the problem is... you cannon run standard bearings on them, (p bearings) you must run H bearings.
The P bearings are more or less an oval shape, when torqued down, and keep the oil pressure up.
the H bearings are round, and generally run larger tolerances, but they will fit a crank with the wide radai. they are needed for these cranks.
Forgive me if i've spelled radia wrong every time, i just can't remember the latin suffix plural form of radius.... all that schooling gone to waste
the differnce in 4130/4340 is the type of steel and the how it was forged.
4340 is a tougher steel, but generally not used on street motors because of the tolerances needed.
one of the things that make them stronger are the radia on the crank. wider the radia at the journals, the stronger the crank.
the 4130/4340 both have wide radia, with the 4340 being stronger,with a wider radia.
the problem is... you cannon run standard bearings on them, (p bearings) you must run H bearings.
The P bearings are more or less an oval shape, when torqued down, and keep the oil pressure up.
the H bearings are round, and generally run larger tolerances, but they will fit a crank with the wide radai. they are needed for these cranks.
Forgive me if i've spelled radia wrong every time, i just can't remember the latin suffix plural form of radius.... all that schooling gone to waste
01-08-2002, 07:06 PM
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So for a street motor the 4130 is a better crank? I've already got the 2-piece forging connecting rods from eagle. I want the bottom end to be able to take whatever I throw at it.
01-08-2002, 07:50 PM
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Car: 1986 Z28
Engine: 355
Transmission: th400
yeah you can run the H bearings on the 4130 at street tolerances (tighter) and be Ok.
The crank will most likely be the last thing to break.
The crank will most likely be the last thing to break.
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