2-Bolt or 4-Bolt?
Thread Starter
Heel & Toe
Joined: Aug 2004
Posts: 20
Likes: 0
2-Bolt or 4-Bolt?
Okay, guys ... is there way, short of engine disassembly or revelation through Ouija Board, to tell if my L-48's a 2 bolt or 4 bolt main? Does the serial or block number indicate this?
It's beginning to look like bolt-on horsepower component selection choices are, reasonably enough, in large measure determined by this.
Mike
It's beginning to look like bolt-on horsepower component selection choices are, reasonably enough, in large measure determined by this.
Mike
Drifting
Joined: Sep 2001
Posts: 1,427
Likes: 1
From: Boxford Mass
Decode your casting # at this site...
http://www.mortec.com/castnum.htm
Now why is # mains so important for bolt-ons? I don't totally agree with that, unless you are bolting on a Wieand Blower or something...
http://www.mortec.com/castnum.htm
Now why is # mains so important for bolt-ons? I don't totally agree with that, unless you are bolting on a Wieand Blower or something...
Race Director
Joined: Jun 2000
Posts: 10,036
Likes: 668
From: FL
99% of L-48's are 2-bolt, cast main, cast pistons.
I have an all new rotating assembly in my 2-bolt but still decided to build a motor with a power range of 2000-5500 rpm. Fits how I drive and my cruise rpm.
I have an all new rotating assembly in my 2-bolt but still decided to build a motor with a power range of 2000-5500 rpm. Fits how I drive and my cruise rpm.
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Originally Posted by page62
2-bolt mains are good for probably 400 hp...just don't take 'em up to ridiculously high rpms!
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Instructor
Joined: Jan 2004
Posts: 246
Likes: 0
From: Marshalltown Iowa
A 2 bolt main is stronger than a 4 bolt main. One look at the 2 vs. 4 bolt webbing will make you agree.
A splayed 2 bolt block is the strongest with the exception of some aftermarket products.
How many of you know anyone that lost a 2 bolt main on the street? It doesn't happen very often.
A splayed 2 bolt block is the strongest with the exception of some aftermarket products.
How many of you know anyone that lost a 2 bolt main on the street? It doesn't happen very often.
Instructor
Joined: Aug 2000
Posts: 107
Likes: 0
From: Houston Texas
Originally Posted by Jack71
L-48s, which are 2-bolt mains, have the same casting # as L-82s, which are 4-bolt. Chevy used this 0010 casting for many years in "high performance passenger" applications.
Le Mans Master
Joined: Mar 2004
Posts: 7,450
Likes: 1,479
From: Little Rock AR
Not many cranks falling out of small block chevies at the track. 
The rods fail once in a while but the mains/cranks are not the weak link by any means. If you are worried about the bottom end you can install an ARP main stud kit. You can sleep well with that setup. Lots of track cars running that setup.
Add a set of good rod bolts and use forged pistons and forgettabouwdit
Anthing you can drive on the street will survive fine with that.
Remember, GM never even built a 4 bolt main 327. I know the stroke is shorter by .23" but you get the idea.
-Mark.
The rods fail once in a while but the mains/cranks are not the weak link by any means. If you are worried about the bottom end you can install an ARP main stud kit. You can sleep well with that setup. Lots of track cars running that setup.
Add a set of good rod bolts and use forged pistons and forgettabouwdit
Anthing you can drive on the street will survive fine with that. Remember, GM never even built a 4 bolt main 327. I know the stroke is shorter by .23" but you get the idea.
-Mark.
Intermediate
Joined: Jul 2004
Posts: 44
Likes: 0
From: Northville MI
Originally Posted by Eric R
A 2 bolt main is stronger than a 4 bolt main. One look at the 2 vs. 4 bolt webbing will make you agree.
A splayed 2 bolt block is the strongest with the exception of some aftermarket products.
How many of you know anyone that lost a 2 bolt main on the street? It doesn't happen very often.
A splayed 2 bolt block is the strongest with the exception of some aftermarket products.
How many of you know anyone that lost a 2 bolt main on the street? It doesn't happen very often.
This is not exactly true. While the webbing is thicker because of 2 less bolt holes, strength of this area is not what you have to worry about. At high RPM The caps can walk on a 2 bolt. So youll lose your bearings in a hurry. Splayed caps being stronger are only a myth! The only reason that splayed caps are significant in our hobby is that its the simplest way to convert a 2 bolt to 4 bolt block! But You are right that in a street application, your not going to lose a 2 bolt block. I beat the tar out of my the 2 bolt V8 in my mustang and no issues yet
Oops Just noticed Im on my dads account
Noroofmustang is to blame for this post!
Melting Slicks
Joined: Nov 2003
Posts: 2,362
Likes: 1
From: San Antonio TX
Personally I would not worry if it is a 2 bolt or 4 bolt unless as someone else mentioned you were going to turn High RPM lets say above 6500RPM. But if you are going to go above that and up to the sky of say 10,000RPM then only the best parts will do. Years ago I ran a 4 Bolt main with ARP bolts on everything daily into the 9000 to 9500 rpm range and tore the engine down about every 5000miles or less to inspect everything. You need to decide on what you want the engine to do. Once you know that there are many good people on this board that can give good information on the combo to run for the desired effect.
Also I would not worry too much about high HP it is good for bragging but beyound a certain point it just makes the car that much harder to handle. You want a balanced car.
Also I would not worry too much about high HP it is good for bragging but beyound a certain point it just makes the car that much harder to handle. You want a balanced car.
Last edited by SHAKERATTLEROLL; Sep 4, 2004 at 07:28 PM.
