cars

allpar, the Chrysler - Dodge - Plymouth - Jeep site

An Insane Number of Mopar Slant Six Engine Specifications

Journal Number

 

1980 3.7-Liter
(225 CID) Slant Six

12.75' x 0.877"
22.75" x 0.877"
32.75" x 1.107"
42.75" x 0.877"

The engine had four replaceable steel-backed (aluminum alloy on steel) babbitt crankshaft main bearings. Oil grooves were in the upper half of the bearings, and in the lower half of the #1 bearing. The connecting rod bearings were aluminum on steel.

In most years, closed-circuit crankcase ventilation was used; crankcase vapors were routed to the combustion chambers through a PCV valve located in the valve cover. Vapors were burned before being expelled into the air through the exhaust system.

Oil pressure ranged from 35-65 p.s.i. @ 2.000 rp.m.  Crankcase oil capacity was four quarts (one more when changing the filter).

1968 detailed specifications

Engines170 cubic inch225 cubic inch
CarburetorSingle barrelSingle barrel
Bore and Stroke (nominal)3.4 x 3.1253.4 x 4.125
Bore spacing (CL to CL)3.98 (1-2, 3-4, 5-6);
4.0 (2-3, 4-5)
3.98 (1-2, 3-4, 5-6);
4.0 (2-3, 4-5)
Firing Order1-5-3-6-2-41-5-3-6-2-4
Compres. Ratio (nominal)8.58.4
Cylinder Head MaterialCast ironCast iron
Cylinder Block MaterialCast ironCast iron
Cylinder SleeveNoneNone
Number of mtg. points (Front)TwoTwo
Number of mtg. points (Rear)OneOne
Engine Installation AngleLateral 0°, Up 3°Lateral 0°, Up 3°
Taxable Horsepower 27.727.7
Publishing max. bhp* @eng. RPM115@4400145@4000
Publishing max. torque * (lb. ft. @RPM)155@2400215@2400
Weight (piston only ) oz.16.416.4
Clearance (limits) Top land.024 min..024 min.
Clearance (limits) Skirt Top.0005 - .0015.0005 - .0015
Clearance (limits) Skirt Bottom-.0005 - +.0005-.0005 - +.0005
Ring groove depth No. 1 and No. 2 ring.179.179
Ring groove depth No. 3 ring.181.181
Compression RingsTwist and taper, tin-platedTwist and taper, tin-plated
Oil RingsCast iron, steel expanders3-piece abutment-type, stainless steel spacer-expander with chrome-plated segments
Piston Pins170 cubic inches225 cubic inches
Length2.9652.965
Diameter.9008.9008
Type (Locked in rod, in piston, floating, etc.)Press-fit in rodPress-fit in rod
Type (Bushing, in rod or piston)NoneNone
Type (Bushing, material)--
Clearance (In piston).00045 to .00075.00045 to .00075
Clearance (In rod).0007 to .00014 interference.0007 to .00014 interference
Direction & amount offset in pistonRight .06Right .06
Connecting Rods170 cubic inches225 cubic inches
Weight (oz.)25.726.8
Length (center to center)5.7076.699
Bearing (material & type)Lead-based babbitt on steelLead-based babbitt on steel
Bearing (overall length).985.985
Bearing (clearance [limits]).0002 to .0022.0002 to .0022
Bearing (end play).006 - .012.006 - .012
Carburetors (Valiant)170225
Idle speed – Manual*750650
Idle speed– Automatic*750650
Idle air-fuel mixture*14.0 – 14.414.0 – 14.4
TransmissionManual, AutomaticManual, Automatic
Carburetors (Make)Ball and Ball**Holley
Carburetors (Model)BBS-4414 S (Manual), BBS-4415 S (Automatic)R-3919 A (Manual), R-3920 A (Automatic)
No. used and type1, 1-bbl1, 1-bbl
Barrel Size1.56 (Manual), 1.69 (Automatic)1.69
Suspension details (Valiant)170 225
Front spring height by diameter 35.8 x 0.8335.8 x 0.83
Spring – Rate at wheel (lb. per in.)8585
Number of leaves in rear springs45
   

1968 Slant Six crankshafts

MaterialDrop-forged steel
Vibration Damper TypeNon-adhesive, rubber, dynamic
End thrust taken by bearing (No.)Three
Crankshaft end play.002 - .007
Main bearing (material & type)Lead-base babbitt on steel, removable, precision
Main bearing (clearance).0002 - .0022 specified,
.0005 - .0015 desired
Main bearing (Journal dia. and bearing overall length) No. 12.75 x 1.034
Main bearing (Journal dia. and bearing overall length) No. 22.75 x 1.034
Main bearing (Journal dia. and bearing overall length) No. 32.75 x 1.254
Main bearing (Journal dia. and bearing overall length) No. 42.75 x 1.034
Crankpin journal diameter2.187

1968 slant six camshafts were hardened cast iron, with the oil pump and distributor drive gears cast integrally; bearings were lead-based babbitts on steel. There were four bearings. The crank sprocket was made of malleable cast iron or sintered iron (Super Oilite). The cam sprocket was cast iron.

1968 slant six valves

ModelSlant Six
LiftersMechanical
Valve Rotator, type (intake, exhaust)Low-friction lock on exhaust
Rocker ratio1.5
Operating tappet clearance (Intake).010 hot
Operating tappet clearance (Exhaust).020 hot
Timing (Intake – opens [°BTC])10
Timing (Intake – closes [°ABC])50
Timing (Intake – duration –deg.)240
Timing (Exhaust – opens [°BBC])50
Timing (Exhaust – closes [°ATC])6
Timing (Exhaust – duration –deg.)236
Timing (Valve opening overlap)16
Intake (Overall length)4.77
Intake (Actual overall head dia.)1.62
Intake (Angle of seat & face, deg)Seat: 44.5 – 45;
valve: 45 – 45.5
Intake (Seat insert material)None
Intake (Stem diameter).372 - .373
Intake (Stem to guide clearance).001 - .003
Intake (Lift [@zero lash]).394
Intake (Outer spring press. & length – valve closed, lb@in.)62 @ 1.65
Intake (Outer spring press. & length – valve open, lb@in.)154 @ 1.26
Intake (Inner spring press. & length – valve closed, lb@in.)None
Intake (Inner spring press. & length – valve open, lb@in.)None
Exhaust (Material)21 – 4N
Exhaust (Overall length)4.80
Exhaust (Actual overall head dia.)1.36
Exhaust (Angle of seat & face, deg)47 – 47.5
Exhaust (Seat insert material)None
Exhaust (Stem diameter). 371 - .372
Exhaust (Stem to guide clearance).002 - .004
Exhaust (lift [@zero lash]).390
Exhaust (Outer spring press. & length – valve closed, lb@in.)62 @ 1.65
Exhaust (Outer spring press. & length – valve open, lb@in.)154 @ 1.26
Exhaust (Inner spring press. & length – valve closed, lb@in.)None
Exhaust (Inner spring press. & length – valve open, lb@in.)None

1968 Slant Six Timing

170 Manual170 Auto.225 Manual225 Auto.
Timing (Degrees)5 ATC2.5 ATCTDCTDC
Timing (@RPM)700700650650
Distributor2875199287520228753642875366

 

Distributor Part No.Centrifugal Advance (Crank ° @ RPM) Vacuum Advance (Crank ° @ Inches of Mercury)
StartIntermediateMaximumStartIntermediateMaximum
28751990 @ 700-10000-7.4 @ 1000, 24.4-28 @ 198034-38 @ 44000 @ 5-7.16-12 @ 8.512-17 @ 10
28752020 @ 700-10000-13.4 @ 1000, 18.4-22.4@142028-32 @ 44000 @ 5-7.16-12 @ 8.512-17 @ 10
28753640 @ 700-10000-7.4 @ 1000, 18.4-22.4@174025-29 @ 40000 @ 6.2-9.74-10 @ 11.97.4-12.4 @ 13.8
28753660 @ 700-10000-7.4 @ 1000, 18.4-22.4@174025-29 @ 40000 @ 5-75-11 @ 87.4-12.5 @ 8.7

Joseph Newhouse provided the following chart which applies to slant six powered cars from 1959 to 1978. Trucks could be rated somewhat lower than cars (140 hp vs 145 hp gross). These are Federal numbers and could vary in California by 10-15 hp. The slant six continued in use through to 1987 in Mexico, where, with a rejetted Carter YPF two-barrel carburetor and recurved distributor to reduce emissions by 30%, it was rated at 98 hp net.

EngineYear(s)
Available
Compression
Ratio
Horsepower @ RPM
(see note)
Torque  (lb-ft) @ RPM
(see note)
1701959-19638.2 to 1101 @ 4400155 @ 2400
1701964-19668.5 to 1101 @ 4400155 @ 2400
1701967-19698.5 to 1115 @ 4400155 @ 2400
1981970-19718.4 to 1125 @ 4400180 @ 2000
19819728.4 to 1100 @ 4400160 @ 2400
19819738.4 to 195 @ 4000150 @ 1600
19819748.4 to 195 @ 4000145 @ 2000
2251960-19628.5 to 1145 @ 4000215 @ 2800
22519638.2 to 1145 @ 4000215 @ 2400
2251964-19718.4 to 1145 @ 4000215 @ 2400
22519728.4 to 1110 @ 4000185 @ 2000
22519738.4 to 1105 @ 4000185 @ 1600
22519748.4 to 1105 @ 3600180 @ 1600
22519758.4 to 195 @ 3600170 @ 1600
2251976-788.4 to 1100 @ 3600170 @ 1600
225-2V1977-788.4 to 1110180

Heavy-duty slant six engines used in industrial and some truck/bus applications used a double-row roller timing chain (but just one chain!), chrome-plated upper piston rings, and other features depending on service duty (polyacrylic valve stem seals, positive valve rotators, stellite-faced exhaust valves, and/or a high-volume oil pump); Rodger also said some fleet cars had these. You can retrofit the double roller chain and gears into car slant sixes, according to some sources; the double row timing chain is NAPA part 9168, used from 1962 to 1975 on the slant six; the sprockets are part S338 and S339 (thanks, Rodger).

1960 Slant Six
vs GM and Ford
Ford 223Slant Six 225Chevrolet HyThrift
145 hp145 hp135 hp
206 lb-ft 215 lb-ft 207 lb-ft
ChokeManualFast-reaction automaticTube-fed automatic

Recommended links

See the menus on top of the pages! • We are not responsible for the consequences of actions taken based on this site and make no guarantees regarding validity, accuracy, or applicability of information, predictions, or advice of any sort. Please read the terms of use and privacy policy. Copyright © 1994-2000, David Zatz; copyright © 2001-2014, Allpar LLC (except as noted, and press/publicity materials); all rights reserved. Dodge, Jeep, Chrysler, Ram, and certain other names are trademarks of Chrysler, LLC, not us. Allpar — your source for the story of Chrysler, Jeep, Ram, and Dodge cars and trucks.