Four bolt main vs. two bolt main
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Four bolt main vs. two bolt main
Members of the forum I have a question.My 75 is a L48 with the two bolt main. My 78 is an L82 with the four bolt main. Question: Other than extra horsepower what seperates the two motors? How does the construction differ?? Thanks
Safety Car
Joined: Aug 2006
Posts: 4,102
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From: Forsyth Illinois
Are you sure that the L82 is 4-bolt?I ask,cause i've had correct L82's that weren't.A 2-bolt is no worse off than a 4-bolt unless you're over 500 horse,and a rpm engine.4-bolts are bragging rights engines.
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From: NM
Originally Posted by 78Shadz75
My 75 is a L48 with the two bolt main. My 78 is an L82 with the four bolt main. Question: Other than extra horsepower what seperates the two motors? How does the construction differ??
L48 = 2-bolt mains, Drop forged steel Rods, Nodular Iron crankshaft, Cast aluminum alloy pistons, 8.5:1 compression, 195/210 duration cam, 1.94" 1.50" valves.
L82 = 4-bolt mains, Drop forged steel rods, forged steel crankshaft, alum impact extruded pistons, 9.0:1 compression, 222/222 duration cam, 2.02" & 1.60" valves.
Safety Car
Joined: Aug 2006
Posts: 4,102
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From: Forsyth Illinois
No,all L82's aren't 4-bolt,nor are they all 2.02 heads.Incorrect info.there.In 73 you could get a L82 w/2.02s,OR 1.94s,then in 74 up,i believe,they were all the 1.94s.When you pull your pan on the 78,don't be surprised by if it's only a 2-bolt,bud.And they're fine for street use.In 78 yours will have a aluminum intake vs.the cast for the L48.Heads are all the same for all the 350s in 78(casting #462624)to 82,except the 80 LG4 California 305.You have a hotter cam,and a aluminum intake,which is what makes your engine different than the base L48.The pistons,and all that will all be the same.Tom73 is probably pulling info.from a 73,which would be correct,but isn't correct for the later years til the option was gone in 82.
Last edited by vettesbydesign; Dec 12, 2006 at 09:20 PM.
Burning Brakes
Joined: Nov 2004
Posts: 1,193
Likes: 176
From: Hillsborough NC
78 L-82 has
4 bolt main
windage tray
2.02/1.60 valves (head casting ending in 881)
pushrod guide plates
forged crank
flat top forged pistons
aluminum intake
dual snorkel air cleaner
forged crank
This info is as per the GM specs.
4 bolt main
windage tray
2.02/1.60 valves (head casting ending in 881)
pushrod guide plates
forged crank
flat top forged pistons
aluminum intake
dual snorkel air cleaner
forged crank
This info is as per the GM specs.
Le Mans Master
Joined: Jul 2005
Posts: 5,752
Likes: 4
From: Austin Texas
Every L-82 I have rebuilt..(too many) had all of the above.L-82 had heads ending in ...545 in '73, all others ended in ....882 'till '78, then ...624..
Last edited by big_G; Dec 12, 2006 at 01:54 PM.
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Race Director
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From: NM
You have a hotter cam,and a aluminum intake,which is what makes your engine different than the base L48.The pistons,and all that will all be the same.
Race Director
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What is an L-82?
The L-82 made it's debut in 1973 as the throttled down smog successor to the original LT-1. With a 9.0:1 compression ratio, 2.02-inch intake/1.60-inch exhaust valves, and hydraulic lifters, it was rated at 250 net horsepower at 5,200 rpm and 285 lb-ft of torque at 4,000 rpm. The L-82 has large port cylinder heads, pushrod guideplates, a long duration camshaft, a forged-steel crankshaft, moly rings, finned aluminum valve covers, a high capacity starter and a four-bolt block.
Horsepower ratings varied from year to year as Chevrolet attempted to meet changing emissions and fuel economy requirements. L-82 horsepower ratings ranged from a high of 250 in 19'73-19'74 to a low of 205 in 19'75. In 1980, it's last year of production, the L-82 was rated at 230 horsepower.
Year Horsepower Quantity
1973 250 5,710
1974 250 6,690
1975 205 2,372
1976 210 5,720
1977 210 6,148
1978 220 12,739
1979 225 14,516
1980 230 5,069
The L-82 made it's debut in 1973 as the throttled down smog successor to the original LT-1. With a 9.0:1 compression ratio, 2.02-inch intake/1.60-inch exhaust valves, and hydraulic lifters, it was rated at 250 net horsepower at 5,200 rpm and 285 lb-ft of torque at 4,000 rpm. The L-82 has large port cylinder heads, pushrod guideplates, a long duration camshaft, a forged-steel crankshaft, moly rings, finned aluminum valve covers, a high capacity starter and a four-bolt block.
Horsepower ratings varied from year to year as Chevrolet attempted to meet changing emissions and fuel economy requirements. L-82 horsepower ratings ranged from a high of 250 in 19'73-19'74 to a low of 205 in 19'75. In 1980, it's last year of production, the L-82 was rated at 230 horsepower.
Year Horsepower Quantity
1973 250 5,710
1974 250 6,690
1975 205 2,372
1976 210 5,720
1977 210 6,148
1978 220 12,739
1979 225 14,516
1980 230 5,069
Race Director
Joined: Jan 2003
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From: State of Confusion
..... slightly off-topic / please bear with me.....
Has anybody taken-apart an unmolested L-83 / Cross-Fire, and if-so, what does it's internals consist of:
I'm told it's (9.2:1 compression-ratio with large chamber head ) pistons are forged, but is the crank steel, and does it have 4-bolt main-caps (both highly-doubtful )
Thanks-in-advance!
Glen
Has anybody taken-apart an unmolested L-83 / Cross-Fire, and if-so, what does it's internals consist of:
I'm told it's (9.2:1 compression-ratio with large chamber head ) pistons are forged, but is the crank steel, and does it have 4-bolt main-caps (both highly-doubtful )
Thanks-in-advance!
Glen