This effort is by no means an original or finished idea of course… but for the sake of additional clarity, I often refer to and drop links like these in my Major Engine Repair postings. So I thought it would make more sense to put all of these important “Library Books, PDFs and Magazine Articles... And Most Important of All: Tech Specifications and Engine Component-fastener Tolerances” I found in one place and on one shelf for the ease and speed of having some Quick Technical References when either necessity or the mood strikes anyone to read up on and obtain a deeper understanding of the GM Atlas LL8 4.2L Engine. Grabbing and Saving these links to all this stuff can save you hours of search time with “0” Hassles in finding the data ...sooner than later:
This first PDF is from GM’s Archives and represents their earliest Marketing and Sales data that their Dealerships received as the ways and means to motivate the Customer Base to buy these SUVs:
https://archives.media.gm.com/division/powertrain/news/4200_Overview.pdf
Similarly, by reading this “White Paper” PDF written way back in 2000… GM’s Senior Engineers like Mr. Ron Kociba (arguably “The Genius Father of the GM Atlas Vortec Engines”...) could help their customers improve upon their overall understanding of … and marvel at the inner workings of the GM Atlas 4.2L LL8. This one is particularly adept at explaining the Engineering Reasoning behind many of its unique design features that have become both the ‘Blessings and Curses’ we all eventually experience ...and have to figure out how to fix:
http://vortec4200.com/index_htm_files/vortec4200.pdf
These are the Basic GM Engine Specs:
https://archives.media.gm.com/division/powertrain/news/4200_Spec.pdf
And here is a Technical Article from “Super Chevy Magazine” with Unique Engine Cutaway Views:
http://www.superchevy.com/how-to/83758-chevrolet-vortec-4200-inline-six-engine/
Here is a News Article from The Orlando Sentinel with an interview of Mr. Kociba, himself:
http://articles.orlandosentinel.com/2000-09-21/news/0009210429_1_engine-inline-four-valves
This is the “Official” GM Atlas LL8 4.2L Engine Wiki:
https://en.wikipedia.org/wiki/General_Motors_Atlas_engine
...and here is the OTHER Chevy GM Atlas LL8 4.2L Engine Wiki:
http://www.chevy-wiki.com/wiki/GM_Atlas_engine
...and of course… There is always One More Wiki:
https://en.wikipedia.org/wiki/Chevrolet_TrailBlazer
Here is an interesting Posting from an ‘Other Forum' covering an effort with “How-To-Build a Turbocharged GM 4.2L Atlas LL8 Engine” for a Roadster:
https://www.theturboforums.com/threads/372350-Vortec-4200-L6-turbo-build
This is a Good Technical Article on “How to Install a Crankshaft… so it Does NOT get Cranky”:
http://www.superchevy.com/how-to/engines-drivetrain/0707ch-main-bearing-clearance/
Proper Installation of TTY Bolts (FelPro)
http://www.felpro-only.com/blog/proper-installation-use-t-t-y-bolts/
This next section is like 'The Collated Keys to The House of Vortec'. This information was very hard to find and organize and at one time or another, will become "Very Important Stuff to Know"... because you cannot get in through the Front Door without them. So its worth a Copy-Paste of this information into a libreoffice Word Processor Document... and then saved around in triplicate so that when you really need to find out the Accurate Engine Tolerances when working more intimately inside of the GM Atlas 4.2L LL8 Engine... they'll be right there... handy for you so you won't have to guess:
The GM Atlas LL8 4.2L Technical Engine Rotating Components Tolerance List:
Engine Type - In-Line-6
Displacement - 4.2L 256 cu inch
RPO (VIN Code) - LL8
Spark Plug Gap - Maximum 0.050 inch - Minimum 0.044 inch
Bore - 3.66 inch Stroke - 4.02 inch
Compression Ratio - 10: 1
Firing Order - 1-5-3-6-2-4
Oil Pressure - (At the sending unit) Warm - Minimum - 12 psi - 1200 RPM
Cylinder Bore Diameter - 3.6638 to 3.6644 inch
Cylinder Out Of Round - Maximum - 0.0005 inch
Cylinder Liner Recession - Maximum - 4.02 inch
Compression Ratio- 0.0006 inch
Piston & Pin Piston Diameter - (1.4961 inch) down from top 3.6627-3.6633 inch
Piston to Bore Clearance- 0.0004 to 0.0017 inch
Piston to Pin Clearance- 0.00012 to 0.0005 inch
Piston Pin Bore - 0.9056 to 0.9058 inch
Piston Pin Diameter - 0.9054 to 0.9055 inch
Piston Ring - Top Groove to Ring Side Clearance- 0 0017 to 0.0037 inch
Piston Second Groove to Ring Side Clearance - 0.0017 to 0.0037 inch
Piston Oil Control Groove to Ring Side Clearance- 0.0023 to 0.0085 inch
Piston Top Ring Gap - (3.66 inch) down from top of cylinder- 0 0079 to 0.0157 inch
Piston Second Ring Gap - (3.66 inch) down from top of cylinder -0.0118 to 0.0197 inch
Piston Oil Control Ring Gap- (3.66 inch) down from top of cylinder- 0.0098 to 0.0299 inch
Crankshaft Main Journal Diameter- 2.7567 to 2.7574 inch
Crankshaft Main Journal Taper - Maximum - 0.0002 inch
Crankshaft Main Journal Out Of Round - Maximum - 0.0002 inch
Cylinder Block Main Bearing Bore Diameter - 3.0760 to 3.0766 inch
Crankshaft Main Bearing Inside Diameter - 2.7579 to 2.7592 inch
Crankshaft Main Bearing Clearance - 0.0004 to 0.0025 inch
Crankshaft End Play - 0.0044 to 0.0153 inch
Connecting Rod Bearing Journal Diameter - 2.2337 to 2.2342 inch
Connecting Rod Bearing Journal Out Of Round - Maximum - 0.0002 inch
Connecting Rod Bearing Bore Diameter - 2.3749 to 2.3755 inch
Connecting Rod Inside Bearing Diameter - 2.2351 to 2.2362 inch
Connecting Rod Bearing Journal Clearance - 0.0008 to 0.0025 inch
Connecting Rod Side Clearance - 0.0019 to 0.0137 inch
Connecting Rod Bushing to Pin Clearance - 0.0004 to 0.0007 inch
Connecting Rod Inside Bushing Diameter - 0.9055 to 0.9060 inch
Camshaft Journal Diameter - All Intake and Exhaust #2 - #7- 1.0612 to 1.0622 inch
Camshaft Journal Diameter - Exhaust #1 - 1.1794 to 1.1804 inch
Camshaft Bore Diameter - All Intake and Exhaust #2 - #7 - 1.0638 to 1.0646 inch
Camshaft Bore Diameter-Exhaust #1 - 1.1820 to 1.1828 inch
Camshaft Journal Clearance - 0.0015 to 0.0033 inch
Camshaft End Play - Intake - 0.0020 to 0.0079 inch
Camshaft End Play - Exhaust - 0.0017 to 0.0084 inch
Valve System Stationary Lash Adjuster Hydraulic
Valve Seat Run-out - Maximum - 0.002 inch
Valve Face Run-out - Maximum - 0.0015 inch
Valve Stem Clearance - Intake - 0.0011 to 0.0025 inch
Valve Stem Clearance - Exhaust – 0.0015 to 0.0030 inch=
Valve Spring Load (Closed) - 47.5 to 52.5 lb @ 1.701 inch
Valve Springs Load (Open) - 130 to 142 lb @ 1.260 inch
Oil Pump Gear Pocket Depth – 0.615 to 0.614 inch
Oil Pump Gear Pocket Diameter - 3.430 to 3.429 inch
Oil Pump Drive Gear Outer Diameter Tolerance - 2.893 to 2.891 inch
Oil Pump Drive Gear Width – 0.613 to 0.611 inch
Oil Pump Driven Gear Outer Diameter Tolerance – 3.428 to 3.426 inch
Oil Pump Driven Gear Width - 0.605 to 0.611 inch
Oil Pump Lobe Inner Diameter - Maximum - 0.469 inch
Oil Pump Gear Valve to Bore Clearance - 0.575 to 0.574 inch
Partial Torque Table for the Critical Engine Fasteners:
Plastic Cylinder Head Plugs: 44 Inch Pounds
Timing Chain Cover: 89 Inch Pounds
Delphi Cam Phaser: 18 Foot Pounds + 135 Degrees TTY
Upper Timing Chain Guide: 08 Foot Pounds (89 Inch Pounds)
Cloyes Intake Sprocket: 15 Foot Pounds + 100 Degrees TTY
Passenger Side Timing Chain Shoe: 19 Foot Pounds (Upper Pivot)
Driver’s Side Timing Chain Guide: 08 Foot Pounds (89 Inch Pounds) (Upr & Lwr Bolts)
Timing Chain Tensioner: 18 Foot Pounds (Upper and Lower Bolts)
Main Caps:
First Pass is: 25nm or 18 lb ft
Final pass is: 180 degrees
Rod Caps:
First Pass is: 25nm or 18 lb ft
Final Pass is: 110 degrees
Crank-Case-Oil-Pan: 18 Foot Pounds on each side and 89 Inch Pounds on the End Bolts
Intake Manifold: 89 Inch Pounds
Exhaust Manifold: 18 Foot Pounds
Oil Pump Cover Bolts: 89 Inch Pounds
Engine Mount Nut Fasteners: 52 Foot Pounds
Engine Mount Brackets-2-Frame: 81 Foot Pounds
Rear Main Oil Housing Seal: 89 Inch Pounds
Engine Flex-Plate: 18 Foot Pounds + 50 Degrees Tightening (Follow Torque Pattern)
Harmonic Balancer: 110 Foot Pounds + 180 Degrees TTY
Oil Pump Relief Valve Plug: 124 Inch Pounds
Aluminum Engine Head:
Step 1: Tighten the Long Cylinder Head Bolts ( Via Torque Pattern 1→ 14) @ 22 Foot Pounds
Step 2: Tighten the Same bolts in the Same Sequence + an Additional 155 Degrees TTY
Step 3: Tighten Bolt #15 to 62 Inch Pounds + an Additional 120 Degrees TTY
Step 4: Tighten Bolt #16 and Bolt #17 to 62 Inch Pounds + an Additional 60 Degrees TTY
This first PDF is from GM’s Archives and represents their earliest Marketing and Sales data that their Dealerships received as the ways and means to motivate the Customer Base to buy these SUVs:
https://archives.media.gm.com/division/powertrain/news/4200_Overview.pdf
Similarly, by reading this “White Paper” PDF written way back in 2000… GM’s Senior Engineers like Mr. Ron Kociba (arguably “The Genius Father of the GM Atlas Vortec Engines”...) could help their customers improve upon their overall understanding of … and marvel at the inner workings of the GM Atlas 4.2L LL8. This one is particularly adept at explaining the Engineering Reasoning behind many of its unique design features that have become both the ‘Blessings and Curses’ we all eventually experience ...and have to figure out how to fix:
http://vortec4200.com/index_htm_files/vortec4200.pdf
These are the Basic GM Engine Specs:
https://archives.media.gm.com/division/powertrain/news/4200_Spec.pdf
And here is a Technical Article from “Super Chevy Magazine” with Unique Engine Cutaway Views:
http://www.superchevy.com/how-to/83758-chevrolet-vortec-4200-inline-six-engine/
Here is a News Article from The Orlando Sentinel with an interview of Mr. Kociba, himself:
http://articles.orlandosentinel.com/2000-09-21/news/0009210429_1_engine-inline-four-valves
This is the “Official” GM Atlas LL8 4.2L Engine Wiki:
https://en.wikipedia.org/wiki/General_Motors_Atlas_engine
...and here is the OTHER Chevy GM Atlas LL8 4.2L Engine Wiki:
http://www.chevy-wiki.com/wiki/GM_Atlas_engine
...and of course… There is always One More Wiki:
https://en.wikipedia.org/wiki/Chevrolet_TrailBlazer
Here is an interesting Posting from an ‘Other Forum' covering an effort with “How-To-Build a Turbocharged GM 4.2L Atlas LL8 Engine” for a Roadster:
https://www.theturboforums.com/threads/372350-Vortec-4200-L6-turbo-build
This is a Good Technical Article on “How to Install a Crankshaft… so it Does NOT get Cranky”:
http://www.superchevy.com/how-to/engines-drivetrain/0707ch-main-bearing-clearance/
Proper Installation of TTY Bolts (FelPro)
http://www.felpro-only.com/blog/proper-installation-use-t-t-y-bolts/
This next section is like 'The Collated Keys to The House of Vortec'. This information was very hard to find and organize and at one time or another, will become "Very Important Stuff to Know"... because you cannot get in through the Front Door without them. So its worth a Copy-Paste of this information into a libreoffice Word Processor Document... and then saved around in triplicate so that when you really need to find out the Accurate Engine Tolerances when working more intimately inside of the GM Atlas 4.2L LL8 Engine... they'll be right there... handy for you so you won't have to guess:
The GM Atlas LL8 4.2L Technical Engine Rotating Components Tolerance List:
Engine Type - In-Line-6
Displacement - 4.2L 256 cu inch
RPO (VIN Code) - LL8
Spark Plug Gap - Maximum 0.050 inch - Minimum 0.044 inch
Bore - 3.66 inch Stroke - 4.02 inch
Compression Ratio - 10: 1
Firing Order - 1-5-3-6-2-4
Oil Pressure - (At the sending unit) Warm - Minimum - 12 psi - 1200 RPM
Cylinder Bore Diameter - 3.6638 to 3.6644 inch
Cylinder Out Of Round - Maximum - 0.0005 inch
Cylinder Liner Recession - Maximum - 4.02 inch
Compression Ratio- 0.0006 inch
Piston & Pin Piston Diameter - (1.4961 inch) down from top 3.6627-3.6633 inch
Piston to Bore Clearance- 0.0004 to 0.0017 inch
Piston to Pin Clearance- 0.00012 to 0.0005 inch
Piston Pin Bore - 0.9056 to 0.9058 inch
Piston Pin Diameter - 0.9054 to 0.9055 inch
Piston Ring - Top Groove to Ring Side Clearance- 0 0017 to 0.0037 inch
Piston Second Groove to Ring Side Clearance - 0.0017 to 0.0037 inch
Piston Oil Control Groove to Ring Side Clearance- 0.0023 to 0.0085 inch
Piston Top Ring Gap - (3.66 inch) down from top of cylinder- 0 0079 to 0.0157 inch
Piston Second Ring Gap - (3.66 inch) down from top of cylinder -0.0118 to 0.0197 inch
Piston Oil Control Ring Gap- (3.66 inch) down from top of cylinder- 0.0098 to 0.0299 inch
Crankshaft Main Journal Diameter- 2.7567 to 2.7574 inch
Crankshaft Main Journal Taper - Maximum - 0.0002 inch
Crankshaft Main Journal Out Of Round - Maximum - 0.0002 inch
Cylinder Block Main Bearing Bore Diameter - 3.0760 to 3.0766 inch
Crankshaft Main Bearing Inside Diameter - 2.7579 to 2.7592 inch
Crankshaft Main Bearing Clearance - 0.0004 to 0.0025 inch
Crankshaft End Play - 0.0044 to 0.0153 inch
Connecting Rod Bearing Journal Diameter - 2.2337 to 2.2342 inch
Connecting Rod Bearing Journal Out Of Round - Maximum - 0.0002 inch
Connecting Rod Bearing Bore Diameter - 2.3749 to 2.3755 inch
Connecting Rod Inside Bearing Diameter - 2.2351 to 2.2362 inch
Connecting Rod Bearing Journal Clearance - 0.0008 to 0.0025 inch
Connecting Rod Side Clearance - 0.0019 to 0.0137 inch
Connecting Rod Bushing to Pin Clearance - 0.0004 to 0.0007 inch
Connecting Rod Inside Bushing Diameter - 0.9055 to 0.9060 inch
Camshaft Journal Diameter - All Intake and Exhaust #2 - #7- 1.0612 to 1.0622 inch
Camshaft Journal Diameter - Exhaust #1 - 1.1794 to 1.1804 inch
Camshaft Bore Diameter - All Intake and Exhaust #2 - #7 - 1.0638 to 1.0646 inch
Camshaft Bore Diameter-Exhaust #1 - 1.1820 to 1.1828 inch
Camshaft Journal Clearance - 0.0015 to 0.0033 inch
Camshaft End Play - Intake - 0.0020 to 0.0079 inch
Camshaft End Play - Exhaust - 0.0017 to 0.0084 inch
Valve System Stationary Lash Adjuster Hydraulic
Valve Seat Run-out - Maximum - 0.002 inch
Valve Face Run-out - Maximum - 0.0015 inch
Valve Stem Clearance - Intake - 0.0011 to 0.0025 inch
Valve Stem Clearance - Exhaust – 0.0015 to 0.0030 inch=
Valve Spring Load (Closed) - 47.5 to 52.5 lb @ 1.701 inch
Valve Springs Load (Open) - 130 to 142 lb @ 1.260 inch
Oil Pump Gear Pocket Depth – 0.615 to 0.614 inch
Oil Pump Gear Pocket Diameter - 3.430 to 3.429 inch
Oil Pump Drive Gear Outer Diameter Tolerance - 2.893 to 2.891 inch
Oil Pump Drive Gear Width – 0.613 to 0.611 inch
Oil Pump Driven Gear Outer Diameter Tolerance – 3.428 to 3.426 inch
Oil Pump Driven Gear Width - 0.605 to 0.611 inch
Oil Pump Lobe Inner Diameter - Maximum - 0.469 inch
Oil Pump Gear Valve to Bore Clearance - 0.575 to 0.574 inch
Partial Torque Table for the Critical Engine Fasteners:
Plastic Cylinder Head Plugs: 44 Inch Pounds
Timing Chain Cover: 89 Inch Pounds
Delphi Cam Phaser: 18 Foot Pounds + 135 Degrees TTY
Upper Timing Chain Guide: 08 Foot Pounds (89 Inch Pounds)
Cloyes Intake Sprocket: 15 Foot Pounds + 100 Degrees TTY
Passenger Side Timing Chain Shoe: 19 Foot Pounds (Upper Pivot)
Driver’s Side Timing Chain Guide: 08 Foot Pounds (89 Inch Pounds) (Upr & Lwr Bolts)
Timing Chain Tensioner: 18 Foot Pounds (Upper and Lower Bolts)
Main Caps:
First Pass is: 25nm or 18 lb ft
Final pass is: 180 degrees
Rod Caps:
First Pass is: 25nm or 18 lb ft
Final Pass is: 110 degrees
Crank-Case-Oil-Pan: 18 Foot Pounds on each side and 89 Inch Pounds on the End Bolts
Intake Manifold: 89 Inch Pounds
Exhaust Manifold: 18 Foot Pounds
Oil Pump Cover Bolts: 89 Inch Pounds
Engine Mount Nut Fasteners: 52 Foot Pounds
Engine Mount Brackets-2-Frame: 81 Foot Pounds
Rear Main Oil Housing Seal: 89 Inch Pounds
Engine Flex-Plate: 18 Foot Pounds + 50 Degrees Tightening (Follow Torque Pattern)
Harmonic Balancer: 110 Foot Pounds + 180 Degrees TTY
Oil Pump Relief Valve Plug: 124 Inch Pounds
Aluminum Engine Head:
Step 1: Tighten the Long Cylinder Head Bolts ( Via Torque Pattern 1→ 14) @ 22 Foot Pounds
Step 2: Tighten the Same bolts in the Same Sequence + an Additional 155 Degrees TTY
Step 3: Tighten Bolt #15 to 62 Inch Pounds + an Additional 120 Degrees TTY
Step 4: Tighten Bolt #16 and Bolt #17 to 62 Inch Pounds + an Additional 60 Degrees TTY
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