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Ram Engine Specs 3.9L Magnum V6
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The 3.9L 238 cid six cylinder engine is a V-type, lightweight, single cam, overhead valve engine with hydraulic roller tappets. This engine is designed to run on unleaded fuel with a minimum octane rating of 87.

Engine Type
238 cid 90deg V-6 OHV 

1997 HP Curve

1994 engine serial no. stamped into a machined pad on the left front corner of the engine block.
X M 3.9L T XXXX XXXXXXXX

  • X= Last Digit of model year
  • M=plant - M Mound Road
  •                 S Saltillo
  •                 T Trenton
  •                 K Toluca
  • 3.9L = Engine displacement
  • T= Usage - T Truck
  • XXXX = Month/day
  • XXXXXXXXX = last 8 VIN digits

2001-2001 serial no:
X M AAA YYYY XXXX

  • X= Last Digit of model year
  • M=plant - M Mound Road
  •                 S Saltillo
  •                 T Trenton
  •                 K Toluca
  • AAA Engine displacement (cid)
  • YYYY = Month/day
  • XXXX = Engine Serial code
Horsepower
175 hp @ 4400 rpm
Bore x Stroke
3.91 x 3.31 in.
(99.3 x 84.0 mm.)
Displacement
238 cu.in. (3.9 L) 
Compression Ratio 
9.1 :1 
Cylinder Compression Pressure
100 psi
Torque 
230 ft. lbs. (312 N.m) @ 3200 rpm
Firing Order
1-6-5-4-3-2 
Lubrication
Pressure Feed - Full Flow Filtration
Engine Oil Capacity 
4.0 Qts. ( 3.8 L ) with filter
Oil Pressure

Idle 6psi
3000 rpm 30-80 psi

Oil pressure warning
5-7 psi
Cooling System
Liquid Cooled - Forced Circulation 
Cooling Capacity
15.1 Qts. (14.3 L)
Cylinder Block
Cast Iron 
Cylinder Head
Cast Iron 
Combustion Cambers 
" Fast Burn " Design 
Pistons
Aluminum Alloy with Strut 
Distributor Rotation
Clockwise
Spark Plugs: 14mm thread, 19mm reach, 16mm hex wrench, resistor
  Year   Manufacturer   Part No.   Stock Number Gap   Notes
1994-1996 NGK FR4 5155 .035  
1997-1999 NGK FR5-1 7252 .040  
Camshaft - Nodular Cast Iron
Bearing Number 1 2 3 4
Bearing Diameter mm 50.800 - 50.825 50.394 - 50.419 49.606 - 49.623 39.688 - 39.713
in 2.000-2.001 1.984-1.985 1.953-1.954 1.5625-1.5635
Journal Diameter mm 50.749-50.775 50.343-50.368 49.555-49.581 39.637-39.662
in 1.998-1.999 1.982-1.983 1.951-1.952 1.5605-1.5615

Diametrical Clearance:  0.0254-0.0762 mm,       0.001-0.003 in
Max Allowable:     0.127 mm,     0.005 in
End Play:                0.051-0.254 mm,     0.002-0.010 in
Connecting Rods - Forged Steel
Bearing Clearance . . . . . . . . . 0.0127-0.0559 mm,    0.0005-0.0022 in
Piston Pin Bore Diameter . . . . 24.940-24.978mm,    0.9819-0.9834 in
Side Clearance (two rods) . . . .0.152-3.356mm,    0.006-0.014 in
Total Weight (less bearing) . . . 726 grams,    25.61 oz
Crankshaft - Nodular Cast Iron

Connecting Rod

Journal Diameter . . . . . . . . . . . . .  53.950-53.975 mm,    2.124-2.125 in
Out of Round (max) . . . . . . . . . .    0.0254 mm,    0.001 in
Taper (Max) . . . . . . . . . . . . . . . . . 0.0254 mm,    0.001 in

Diametrical Clearance

No 1: . . . . . . . . . . . . . . . . . . . . . . . 0.0127-0.0381 mm,    0.0005-0.0015 in
No 2, 3, and 4 . . . . . . . . . . . . . . . .  0.0127-0.0508 mm,    0.0005-0.0020 in
Max Allowable (Nos. 2, 3, & 4) . . 0.0635 mm, 0.0025 in

End Play . . . . . . . . . . . . . . . . . . . . . . .  0.051-0.178 mm,    0.002-0.007 in
   Max Allowable . . . . . . . . . . . . . . . .  0.254 mm,    0.010 in

Main Bearing Journals

Diameter . . . . . . . . . . . . . . . . . . . .  63.487-63.513 mm,    2.4995-2.5005 in
Out-of-Round (Max) . . . . . . . . . . . 0.0254 mm,    0.001 in
Taper (Max) . . . . . . . . . . . . . . . . .  0.0254 mm,    0.001 in
Valves
Stem to guide clearance
  • 0.001- 0.003 inch
  • maximum allowable (rocking method) 0.017 inch
Guide Diameter (std) 0.313 - 0.314 inch
 
Intake
Exhaust
Face angle 43.25 - 43.75 degrees 43.25 - 43.75 degrees
Seat Angle 44.25 - 44.75 degrees 44.25 - 44.75 degrees
Seat Width 0.040-0.060"  (1.016-1.524mm) 0.060-0.080"  (1.524-2.032mm)
Head Diameter 1.916 inch (48.666mm) 1.624 inch (41.250 mm)
Length Overall 4.893 - 4.918 inch 4.907 - 4.932 inch
Stem diameter 0.311 - 0.312 inch 0.371 - 0.372
Valve Opens 8 degrees BTC 56 degrees BBC
Valve Closes 65 degres ABC 25 degres ATC
Duration 250 degrees 264 degrees
Valve Overlap
31 degrees
Valve Lift (zero lash)
0.432"
Push Rod Length
6.915-6.935"   175.64-176.15mm

Valve Springs

  • Free length 1.967"   49.962mm
  • Installed height 1.64"  41.66mm
  • Spring Tension
    • Valve closed 85 lbs @ 1.64"
    • Valve open 200 lbs @ 1.212
  • Number of Coils 6.8
  • Wire Diameter 0.177" 4.50mm

This page would not have been possible without the help of Hank LaViers,
who graciously loaned me his extensive Mopar engine library

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Last Update: June 19, 2001