sticky ASAP...

or else we will get dozens more of thoes dreaded posts.

 

Similarities and Differences Between Gen I/II/III...

SIMILARITIES
1. The LS1 Gen III V8 has the same 4.400-inch bore spacing as Gen I and Gen II.

2. 90-degree angle spacing of cylinder banks.

3. Two overhead valves per cylinder

4. Valve train oiled through pushrods.

5. Connecting rod crank pin diameter of 2.100 inch.

6. Lifter diameter of 0.842 inch

7. Single piece rear crank seal (like on later Gen I/II)

8. Starter located on lower passenger side of block.

9. Oil filter located on lower driver side block.

DIFFERENCES
1. Block Length
Gen III 519.0 mm
Gen I/II 553.2 mm

2. Block Width
Gen III 460.0 mm
Gen I/II 434.6 mm

3. Block Deck Height
Gen III 9.240
Gen I/II 9.025

4. Firing Order
Gen III 1-8-7-2-6-5-4-3
Gen I/II 1-8-4-3-6-5-7-2

5. Cylinder Bank Offset
Gen III 0.9488 inch
Gen I/II 0.8800 inch

6. Block Design/Main Cap Mounting
Gen III Deep skirt engine block with 4 vertical and 2 side fasteners in main caps
Gen I/II Mostly 2 bolt mains, some vertical or splayed with 4 bolts. No provision for side bolting into block

7. Distributor Drive
Gen III No distributor capability
Gen I/II Distributor drive at rear of cam

8. Rotation Sensors
Gen III Engine block mounted crank and cam location sensors
Gen I/II No direct electronic crank and cam sensors

9. Weight
Gen III 430 lbs for a complete LS1 (add approx 88 lbs for iron truck block
Gen I/II 531 lbs for most complete Gen I/II's

10. Connecting Rod
Gen III 6.098 inches long On-center beam connecting rod
Gen I/II 5.700 inches long Offset connecting rod 0.060 inch in piston

11. Piston Pin Diameter
Gen III 0.940 inch
Gen I/II 0.927 inch

12. Crank Thrust Bearing Location
Gen III No. 3 (center) main bearing
Gen I/II Rear Main

13. Cylinder Head Ports
Gen III Replicated (All are the same)
Gen I/II Mirrored (pairs of intake and center exhaust ports are mirror images of each other for packaging)

14. Oil Pump
Gen III Gerotor, driven off the crank
Gen I/II Spud gear, driven off distributor

15. Crank Flange Location
Gen III 0.040 inch closer to bellhousing mount on block than Gen I/II
Gen I/II

16. Thermostat Location
Gen III Intake side of water pump
Gen I/II Exit side of engine

17. Intake Inlet Temperature Control
Gen III No coolant or hot oil touches intake
Gen I/II Water passes through and oil hit the bottom of intake

18. Intake Construction
Gen III Intake made of Nylon
Gen I/II Intake made of cast Iron or Aluminum

 

1 correction, the 96-97 LT1(GEN II) had a crank position sensor. and the GEN II ditributor drive was on the front of the cam, right? GEN II reverse flow cooling(enters heads, then block), and the cam(gear, not belt) driven water pump.
just to add fuel to the fire... LT1>LS1.

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