4 bolt vs. 2 bolt main
07-30-2000, 08:37 PM
#1
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Car: 1986 Camaro Z28
Engine: 350
Transmission: T5
Axle/Gears: 3.73 Posi
4 bolt vs. 2 bolt main
What is the difference between the two? Is one better (or more coveted) than the other?
Thanks.
------------------
1985 Camaro Sport Coupe
LG4, 3.08 rear, A4
Bone Stock
1999 Blazer
4x2, 4.3L, 3.42 rears
Decidedly slow
Thanks.
------------------
1985 Camaro Sport Coupe
LG4, 3.08 rear, A4
Bone Stock
1999 Blazer
4x2, 4.3L, 3.42 rears
Decidedly slow
07-30-2000, 08:52 PM
#2
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Car: 1984 Trans Am WS6
Engine: Minirammed 385, 396 RWHP
Transmission: T56
Axle/Gears: 3.73 Moser 12-bolt
The inner main bearing caps of the blocks are different. The 4-bolt main bearing caps have four bolts instead of two. It is stronger and more rigid.
Yet, the two-bolt is no slouch, either. Probably good for most street-going engines. In fact, a 2-bolt block can be converted into a splayed 4-bolt block, which is considered to be stronger than the factory 4-bolt mains. All this talk of strength is confined to one thing: Keeping the crankshaft in-line. Just as critical are the quality and condition of the rod bolts, the bearing clearances, the type of connecting rod, and the quality of the piston. In addition, shot-peening and balancing of the reciprocating assembly aid in strength/survivability of a short block. Finally, the block itself must be dimensionally correct for maximum strength. A 2-bolt block which has been magnafluxed, line-bored, decked, counterbored & de-burred will probably be stronger than a 4-bolt which has just been yanked out of a truck.
------------------
Daniel Burk
http://www.isthq.com/~dan/fcar.html
'84 Trans Am WS6/L69
KB SFC, Moser axles, Torsen Diff. PST suspension, Braided stainless brake lines,
5-point racing harness, Koni struts, 11-inch rear disks,Spohn Adj. torque arm,
Ported 305 heads w/1.94"intake valves, Comp Cams XE262H, Griffen alum. radiator,
Speed-sensitive steering conversion, underdrive pulleys, Crane Hi-6 & more. 1.05g skidpad verified.
Yet, the two-bolt is no slouch, either. Probably good for most street-going engines. In fact, a 2-bolt block can be converted into a splayed 4-bolt block, which is considered to be stronger than the factory 4-bolt mains. All this talk of strength is confined to one thing: Keeping the crankshaft in-line. Just as critical are the quality and condition of the rod bolts, the bearing clearances, the type of connecting rod, and the quality of the piston. In addition, shot-peening and balancing of the reciprocating assembly aid in strength/survivability of a short block. Finally, the block itself must be dimensionally correct for maximum strength. A 2-bolt block which has been magnafluxed, line-bored, decked, counterbored & de-burred will probably be stronger than a 4-bolt which has just been yanked out of a truck.
------------------
Daniel Burk
http://www.isthq.com/~dan/fcar.html
'84 Trans Am WS6/L69
KB SFC, Moser axles, Torsen Diff. PST suspension, Braided stainless brake lines,
5-point racing harness, Koni struts, 11-inch rear disks,Spohn Adj. torque arm,
Ported 305 heads w/1.94"intake valves, Comp Cams XE262H, Griffen alum. radiator,
Speed-sensitive steering conversion, underdrive pulleys, Crane Hi-6 & more. 1.05g skidpad verified.
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