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Cast or Forged Steel Crank?

G

guessguy

Guest
Well I've told you guys that my crank cracked on my 96 CE LT4. I just received a new casted steel crank from Exessive motors. But now the machine shop is saying that I should buy a forged steel because its a 6sp and casted are more fitted for Automatics. Well I called Exessive back and he says that forged cranks are more for high RPM's. I told him my ignition systems kills it at 6000rpms. He said no problem and casted is fine.
Anyone have an opinion? I don't want this thing to crack on me again. Should I buy a forged crank?
thanks all.
 

Hib Halverson

Technical Writer for Internet & Print Media
Joined
Jan 10, 2001
Messages
13,453
Location
CenCoast CA
Corvette
71 04 12 19
If the engine is stock, near stock or mildly modified with the stock rev limit, replace it with another cast crank.

If the engine is heavily modified or is a mild motor that sees regular use above 6500 rpm, use a forged crank.
 
L

Louis Bartay

Guest
LT4 Crank

Hello,
If the added expense is not a factor, I would purchase a Forged crank like the 1970 LT1 350 c.i. 370 H.p. G.M. used as a forging is is much stronger. And I would never use a crank that has been reground as this will grind under the heat treating to a small degree. Are you drag racing with slicks? How did you crack the crank? I never run my Lt4 hard until the motor in at 180 degrees as a cold motor reved at a high R.P.M. will crack the piston at the wrist pins and cause crankshaft failutre. I have 50,000 miles on my 1996 Lt4 with several dozen drag races and the only thing I need is a new throw out bearing (noisey now) but it still works. Also is any one having alternator bearings making noise?? Mine does but still charges great. 140 amp alternators are very over priced and I am looking for some new replacement bearings.
Thanks,
Louis Bartay 1996 Tourch Red Coupe LT4 ZF 6 speed
labartay@swbell.net
 
G

guessguy

Guest
Thanks for the reply. My engine is modified. It is now a 383. But the guy before me that owned it really abused and raced the car quite a bit. It was just unfortunate that when I bought it, the crank cracked on me. I was just driving it like any other day. No race or anything.
Does the original LT4 engine come with a forged crank? I'm not sure why this guy replaced it with a 3.75 casted crank. It has been over 2 months now, and I still have not received my car back. I have really run into some bad luck with this purchase.
 
L

Louis Bartay

Guest
LT4 Crankshaft

The orginal LT4 crank is a cast steel crank that has extra machine work on it. Since you have a 383 I would use a new forged stroker crank from Lutaini or Oliver and make sure that it has been balanced. Good luck and let us know how the rebuild turns out. Also look at S.L.P. Engineering for parts as they have used the LT4 engine in the past.
Regards, Louis Bartay
 

Topless

Well-known member
Joined
Nov 12, 2001
Messages
444
Location
San Diego, CA
Corvette
1992 Convt w/hard top; 2004 Z06 Z16; 1962 327/300
Alternator..

Also is any one having alternator bearings making noise?? Mine does but still charges great. 140 amp alternators are very over priced and I am looking for some new replacement bearings.

Have you asked around for someone to rebuild it? You would get your original case back, and have it rebuilt to factory or custom specs. If you do buy one, be sure that it is not a 140 amp in a 90 amp case. I actually had a dealer install a replacement alternator (not on my vette) that was 55 amp alt case with a built up 75 amp output. It lasted 1 year.
 
L

Louis Bartay

Guest
rebuild 140 amp

I will call around to the different shops in Fort Worth and see if any of the local shops are up to this, as I want someone who really knows what they are doing.
Thanks, Louis
 

Topless

Well-known member
Joined
Nov 12, 2001
Messages
444
Location
San Diego, CA
Corvette
1992 Convt w/hard top; 2004 Z06 Z16; 1962 327/300
Good luck.
 

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