NastyZ28.com - the most comprehensive numbers decoding site on the net   Camaro LM1 Z28 Engine Specifications

The LM-1 is basically the same 350 that was found in every other Chevy car with a 350, i.e. it wasn't "special".
In 1977 the compression was 8.5:1, rated horsepower 170 @ 3800 rpm, Torque 270 ft/lbs. @ 2400 rpm.
In 1978 compression was lowered to 8.2:1. Due to a redesigned and less restrictive cool air ducting system, power was rated at 185 HP @ 4000 rpm, torque 280 ft/lbs @ 2400 rpm.
GM began painting all V8 engines "corparate blue" in 1977.

 

1977 - 1981 LM-1

Installed views: 1977 Z28 LM1 engine | 1980/81 LM1 w/ Cowl induction

1977 - 1981 Z28 Engine (350) - LM1, 170 - 190hp
Block 3970010 2 bolt main
Crankshaft cast iron
Cylinder Head 333882 1.94/1.5" Valves, 75.47cc
Cam 14060651
Intake 14014440
RH Exhaust 346248
LH Exhaust 381863 could be 361863
Alternator:
Water Pump:

Cam specs: Hydraulic, Lift: .390/.410 (intake/exhaust), Duration: 310/320 (i/e), with 1.5 rockers.

Note: Horsepower varies from 1977 to 1981. The major engine components remained the same except as noted.

Carb: See year specific info
Distributor:See year specific info

1980 LM1
Courtesy of Matthew G. Thie.

The LM1 engine was the base Corvette engine. It was used in the Z28, because the original Z28 option meant Camaro with Corvette drivetrain. The main differences, that I am aware of, between this engine and the basic 350 are:

1.) The oil dipstick is on the other side of the engine. I believe this was done to fit the Corvette engine bay. This also caused a Camaro recall to fix a clearance problem with the dipstick tube rubbing against the Air Conditioning tubing, causing Freon loss. The oil pan is different because of the dipstick location.

2.) I was told the casting alloy of the block was changed to a high silicon alloy for longer life.

3.) The camshaft is very unconventional. In addition to having a higher lift on both intake and exhaust,than the standard 350, the timing is about 180 degrees off, compared to any other cam that I have seen. I have compared this cam to an aftermarket RV cam and it looks like the lobes are shifted by one position. When I asked Crane Cams Tech support for about this configuration, they said it would never work. It seems to be derived from the old mechanical lifter Z28 cam that was used in the original Z28 302 engine. (PN 3972178) The specifications that I have for the LM1 cam are:

Lift Intake .2600 Factory Service Manual
Lift Exhaust .2733 Factory Service Manual

These angles were measured from the cam from my LM1.
Lobe Separation 94.64 Deg.
.050 Duration 165.6 Deg. (Crank)
.050 Duration 154.4 Deg. (Crank)

I believe that this cam was designed to raise the dynamic compression ratio because this engine had a very low static compression ratio. (8.2)

4.) The 1980 LM1 was Blue.


Last updated: 10/20/2011
Author: MadMike Maciolek

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