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273/318/340/360 LA Small Block Mopars

SIZE EQUIVALENTS
273 = 4.5L
318 = 5.2L
340 = 5.6L
360 = 5.9L

IDENTIFICATION MARKINGS
All LA blocks have the C.I. displacement in 2 areas:
1. Front of the block on the driver's side, right below the cylinder head. The C.I.D. will be stamped on the block. I have seen a few out there which do not have this information there. But 99% of the time, you will find it there.
2. Driver's side of the block, below the heads, and above the pan rails. This # will always be there.

BLOCK CASTING #s
2465330 273 '64-'66
2536130 273 '65
2806130 273 '65-'69
2536030 318 '67-'75
4006730 318 '76-'79
4104230 318 '80-'83
2780930 340 '68-'73
3577130 340 T/A '70
3418496 360 '71-'74
3870230 360 '75
4006830 360 '76-'80

HEAD CASTING #s Notes
2465315 273 '64-'65 1
2536178 273 '66
2658920 273/318 '67
2843675 273/318 '68-'74
2531894 340 '68-'71 2
3418915 340 T/A '70 3
360 '71 4
340/360 '72 5
3671587 340/360 '73-'74
360 '76
3769973 318 '75-'76
3769974 360 '75-'76
4027163 318 '77-'83
4027593 318 '77-'83
4027596 360/318HP '77-'83 6
4071051 360/318HP '77-'83
4323302 318 '85-'87 7
4323475 3184bbl '85-'87

I will not list chamber volumes because there is just too much variance when dealing with production tolerances. Tolerances can be so bad, that a single head can have variances between chambers. Much less head to head. So we'll leave this be as the only way to know for sure is to measure it yourself.

Notes
1 - Intake manifold bolt holes drilled at different angles
2 - 2.02/1.60 valves
3 - Actually a 360 "J" head with relocated pushrod holes and 2.02/1.60 valves. Requires off set T/A rocker arms. Even has 360 cast on top of an intake runner.
4 - 1.88/1.60 valves "J" head
5 - First year of 1.88/1.60 valves on the 340. "J" head
6 - Really good big port head, But hard to find uncracked due to the use of the Lean Burn System
7 - Swirl Port Head
All 360/340s used the big port head. all 273/318s used the small port head. With the exception of the 4bbl 318s introduced in '78 I believe. I will verify later.

ROD CASTING #s
1618699 273/318 '64-'71
2899062 318 '72-'73
360 '71-'74
2899486 318 '72-'73
2899063 318 '74-'75
3751016 318 '76-'86
3418645 318 '76-'86
360 '74-'80
3870404 This rod can be found in some early '70s 318 and 360s
2899496 340 '68-'73 This rod is also common in Dodge trucks with a pressed pin.

All 273s and 340s used a bushed rod for full floating pistons.
All 318s through '73 were also full floating pin designs.
All 360s used a pressed pin design.
For those unfamiliar with the terms full floating and pressed. They refer to the piston wrist pin retention method. Full floating rods use lock clips on both sides of the piston wrist pin. There is a channel cut into the piston for the clips to hold the wrist pin in position. The wrist pin will spin readily in the rod which is bushed to prevent galling the pin.

On pressed rods, there is an interference fit between the rod and the wrist pin. Your Machinist will heat the rod small end to expand it. Then he will position the piston over the rod and slip the wrist pin into it's proper position. When it cools, the rod will hold the wrist pin tightly in place. The rod and wrist pin effectively become a single unit.

CRANK CASTING #s
Soon to come

CAMSHAFTS
Lift Dur
273 = .395/.405 240/240 '64-'67 Mech 2V
273 = .415/.425 248/248 '65-'67 Mech 4V
273 = .373/.400 240/248 '68-'69 Hyd
273 = .500/.500 '65-'67 Mech 4V HI-PO
318 = .390/.390 244/244 '67 Hyd
318 = .373/.400 240/248 '68-'86 Hyd includes 4V 318
318 = .391/.391 240/240 '85-'86 Hyd Roller
340 = .444/.453 276/284 '68 Hyd '68 4 speed only
340 = .429/.444 268/276 '68-'73 Hyd '68 auto trans and 6V
360 = .410/.412 252/256 '71-'74 Hyd
360 = .429/.444 268/276 '74-'80 Hyd 4V HI-PO 360
360 = .410/.410 252/252 '75-'80 Hyd

DISTRIBUTOR
All LAs have their distributors mounted at the rear. All have a 1-8-4-3-6-5-7-2 firing order. #1 piston being the front cylinder on the driver's side. And all numbers on diver's side are odd #s, passenger side has even #s. All have a clockwise rotor rotation.

OIL PRESSURE SENDING UNIT LOCATION
Rear top of the block next to the distributor. Directly behind the intake manifold favoring the passenger side of the block.

WATER TEMPERATURE SENDING UNIT
Mounted on the intake manifold. Front passenger side

TIMING CASE COVER

TORQUE SPECIFICATIONS
Head Bolts
273/318/340/360 = 95 lb/ft (High perf/comp 105 lb/ft)

Intake Manifold*
273/318/340/360 = 35 lb/ft

* Note: The first 2 years ('64-'65) of the 273 intake manifold 2V or 4V, will not fit other LA engines without modifications. The bolts were drilled at different angles (manifold and head) than all other LAs.

Exhaust Manifolds
273/318/340/360 = 30 lb/ft

Rocker Arm Shaft
273/318/340/360 = 15 - 20 lb/ft

Connecting Rods Cap Bolts
273/318/340/360 = 45 lb/ft

Main Bearing Bolts
273/318/340/360 = 85 lb/ft

Flywheel to Crank Bolts*
273/318/340/360 = 55 - 65 lb/ft
* There are conflicting figures for this torque spec.

Dampener Bolt
273/318/360 = 100 lb/ft
340 = 135 lb/ft

BLOCK DECK HEIGHT
9.599-9.600 blueprint all blocks ***PAY PARTICULAR ATTENTION TO THIS ON 360s!***

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