Of Power - a comparison

Of Power - a comparison Of Power

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Being a direct comparison of the L-82 and the L-48 as they were back in 1978. There were two (2) L-48's (technically) available in 1978, depending on where you lived. But there was only one (1) L-82. The L-82 was up in power from the previous year due to a dual snorkle air cleaner and a slightly less restrictive exhaust system. What is represented here are the differences between the two engines - where the componant is the same for both engines - it is not mentioned

Output

L-48	L-82
Base - All 185bhp @ 4000 rpm 280 ft.lb. @ 2400 rpm	Optional - all 220bhp @ 5200 rpm 260 ft.lb @ 3600 rpm
California & High Altitude (above 4000 ft.) 175bhp @ 3800 265 ft.lb. @ 2400 rpm	The L-82 was not available in California, Maryland, Florida, Oregon, and Washington States; Boston, Mass; Grand Rapids, Mich.; and DesPlaines, Barrington and Cook counties, Illinois.

Transmissions & Gearing

Transmission	L-48			L-82
positraction std in all ratios all available w/ A/C	Base	>4000 ft.	< 4000 ft.	Base	> 4000 ft.	< 4000 ft
4-speed. Manual (2.85 low) MM4 (M20)	3.36:1* n/a Calif.
3-Speed auto MX1	3.08:1# 3.55 Calif		3.55:1	3.55:1
4-Speed manual (2.64 low) MM4 (M20)				3.70:1	3.36:1 rpo G95
4-Speed manual (2.43 low) M-21				3.70:1

4 speed gearing

	MM4(M20) - for L-48	MM4(M20) - for L-82	M-21 ( L-82 only)
1st gear	2.85	2.64	2.43
2nd gear	2.02	1.75	1.61
3rd gear	1.35	1.34	1.23
4th gear	1.00	1.00	1.00
reverse	2.85	2.55	2.35

Engine Components

Description	RPO L-48	RPO L-82
Total Dressed weight	622.4 lbs	640.7 lbs
Cylinder head volumn	75.47 cc	76.18 cc
Compression Ratio	8.2:1	8.9:1
Pistons	Cast aluminum alloy Sump head; closed slipper skirt	Aluminum impact Extruded Flat head; notched, slipper skirt
Piston Weight	21.33 oz	20.38 oz
top land Clearance limits - skirt top skirt bottom	.0235 - .0017 .0007 - .0017	.0305 - .0395 .0046 - .0056
No. 1 Ring groove dia. No. 2 No. 3	3.541 - 3.556 3.541 - 3.556 3.577 - 3.592	3.546 - 3.556 3.546 - 3.556 3.582 - 3.592
Piston pin clearance (in piston)	.00025 - .00035	.00045 - .00055
Piston pin offset (in piston)	Major thrust side - .060	none
Connecting rod weight	13.70 oz.	20.80 oz.
Crankshaft - material	Cast Nodular Iron	Forged Steel
Valvetrain timing - based on top of ramp points	RPO L-48	RPO L-82
opens (BTC) Intake Closes (ABC) Duration (DEG)	28 72 280	52 114 346
opens (BBC) Exhaust Closes (ATC) Duration (DEG)	78 30 288	98 62 340
Valve open overlap (deg)	58	114
Intake valve - head diameter	1.935 - 1.945 in	2.017 - 2.023 in
Intake lift @ zero lash (1.5:1)	0.390 in	0.450 in
Spring pressure @ open valve	180 - 188 lb @ 1.25"	196 - 204 lb @ 1.25"
Exhaust Valve - head diameter	1.495 - 1.505 in	1.595 - 1.605 in
Exhaust valve overall length	4.910 - 4.930 in	4.891 - 4.910 in
Lift @ zero lash	0.410in	0.460 in.
Block - bearing caps (Number, mat'l, attachment)	All 5 - cast iron - 2 bolt	No. 1 & 5 - cast iron - 2 bolt No. 2,3 &4 - nodular iron - 4 bolt
Intake manifold	Cast alloy iron	Aluminum

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