Poly 318 Engine Parts List

(Applicable to 277, 301, 303, 313, 318, 326, 390, 402 engines)

I have compiled a thorough parts list for the poly 318 and other A-block engines using brands I use and trust or for availability for items that have limited manufacturers. For interchange information, see the parts interchangeable page. For other brands, these part numbers should cross-reference. Many of these parts can be found at Summit Racing, JEGS, Speedway Motors, Hughes, Rock Auto, Napa Auto Parts, and other retailers.


  • Cam: LA273/318/340/360 1956 – 1978, Clevite
    • 1979 onward LA/Magnum camshaft bearings changed in design and do not interchange with 1956 – 1978 A/LA.
  • Mains: LA273/318/340, Clevite
    • 1956 – 1973 A-blocks and LA273/318/340 main bearings interchange and use a thrust bearing with a short vertical thrust side, such as Clevite MS540P. The overall diameter of this thrust bearing when installed is 3.374″. These bearings feature an oil groove on one half of the bearing and solid on the other. Depending on the machinist and/or machine setup, some blocks had the thrust bearing block webbing and main cap sides machined with a short rabbit to match the short thrust bearing side, while other blocks had a taller rabbit machined in.
    • 1974 onward LA318/340 blocks had the thrust bearing webbing and main cap sides machined with a taller rabbit and used a thrust bearing with a taller vertical thrust side, such as Clevite MS1344P. The overall diameter of this thrust bearing when installed is 3.53″. The bearings featured a full oil groove on both halves.
    • Before purchasing 1974 onward LA318/340 main bearings with full oil grooves to use in a 1956 – 1973 A/LA block, one must verify that the thrust bearing block webbing and main cap are machined with tall enough rabbits for the taller 1974 onward thrust bearing to fit. If the rabbit is not tall enough and the 1974 onward bearing is used, the bearing will not fully seat and will bind on the crankshaft main journal. If the use of the full oil groove 1974 onward main bearings is desired, you can either have the block/main cap rabbit machined taller, you can sand down the thrust bearing sides, or you can obtain a 1956 – 1973 thrust bearing and use the 1974 onward bearings on the other main journals.
      • Note: Aftermarket forged crankshafts usually require narrow bearings such as Clevite MS540H due to a larger radius on the journals. Consult the crank manufacturer and verify during mock-up.
      • Note: LA360 crankshaft mains are larger than the A-block and LA273/318/340 and cannot be used.
  • Rods: LA273/318/340/360, Clevite
    • Note: Aftermarket forged crankshafts usually require narrow bearings such as Clevite CB481HN due to a larger radius on the journals. Consult the crank manufacturer and verify during mock-up.

Distributor: All LAs and Magnum 318/360 (see my ignition technical article for more details on selecting and timing the ignition system)

  • Recommended: Richard Ehrenberg’s USA-made “HiRev 7500” distributor, control unit, coil, and ballast resistor.
  • Note: Cheap units, such as Pertronix and Proform, are built with inferior Chinese components and often have reliability and performance issues for optimum performance and reliability including erratic and bouncing timing.
  • Note: 2000 – 2013 Mopar Performance distributors with the miniaturized Accel GM HEI internals are prone to erratic timing.

Distributor Gear: LA273/318/340/360

  • Comp Cams 420
  • Howards Cams 94415
  • Crower 76010

Distributor Intermediate Shaft Bushing: Melling M-63030B

Flexplate and Flywheel: 1962 onward A/LA273/318/forged-crank 340 confirmed neutral balanced

  • LA360 and cast-crank 340 flexplates and flywheels can either be neutral balanced or weighted to balance the rotating assembly, so neutral confirmation is required.

Freeze Plugs:

  • 1956 – 1961: Melling MEP14B (brass dish)
  • 1956 – 1961: Sealed Power 3811014 (steel dish)
  • 1962 – 1966: Melling MPE-613BR or Sealed Power 3818010 (brass cup with cam plug)
  • 1962 – 1966: Napa 567014 (brass cup without cam plug)


  • Full Set: FelPro FS7734PT2
  • Full Set: Best Gasket RS579G
  • Cylinder Head: FelPro 7734PT
  • Exhaust Collector: FelPro 9045
    • Confirm OEM diameter
  • Exhaust Manifold: FelPro MS9342B
  • Fuel Pump: FelPro 6579
  • Intake Manifold (superior fiber type): Best Gasket 18019 
  • Intake Manifold (steel, can leak depending on surface trueness): FelPro MS9344SH
  • Oil Pan: FelPro OS6566C2 or 1806
  • Thermostat Housing: FelPro 35063
  • Timing Cover Set: FelPro TCS65631 or TCS45284
  • Valve Covers: FelPro VS11828R or VS11828C
  • All other gaskets: LA273/318/340

Heater Bypass Hose: DAYCO 70476 for 3/4″ barbs


  • Solid: Melling JB2084 or Sealed Power AT2084
  • Hydraulic: Melling JB879
    • Note: LA lifters are the same diameter but are taller than A-block lifters and require shorter custom pushrods.

Oil Filter (canister):

  • Gasket: FelPro 70522
    • Warning: Don’t use the rubber gasket since they are prone to pushing out and leaking.
  • Filter: Wix 51076

Oil Filter (spin-on):

  • Adapter Plate to Block: FelPro 70522
    • Warning: Don’t use the rubber gasket since they are prone to pushing out and leaking.
  • Very Short Filter 3.79”: Wix 51085
  • Short Filter 4.338”: Wix 51068
  • Standard Filter 5.18” 1 qt.: Wix 51515
  • Long Filter 7” 2 qt: Wix 51773

Oil Pump:


  • Cast: Egge L2050
    • Note: Search ebay for the pistons since they are usually cheaper there than through Egge
  • Forged: Race Tec Pistons (California) for custom forged
  • Billet: Gibtec Pistons (Colorado) for custom billet

Piston Rings: Refer to piston manufacturer. I prefer Hastings or Total Seal

Pulley (Crank):

  • 1956 – 1992 A/LA
    • Note: 1970 – 1992 LA273/318/340 dampers and pulleys have a slightly different pulley bolt pattern, so using a 1970 – 1992 pulley on a pre-1970 damper or pre-1970 pulley on a later damper requires elongating pulley holes, which will not have a negative impact on anything.

Pulley (Water Pump):

  • 1956 – 1969 A/LA when using iron lefthand intake short-snout pump.
  • 1970 – 1992 LA when using aluminum righthand intake long-snout pump.

Pushrods: These are OEM lengths, but worn equipment on non-adjustable rocker arms or modified engines may require custom lengths and should be measured on all rebuilds.

  • Solid Lifter: MPR55 or Sealed Power RP3030 (5/16” x 8.418”)
  • Hydraulic Lifter: MPR153 (5/16” x 8.364”)
  • Custom (for LA lifters and/or performance builds): OE Pushrods or Smith Brothers

Rocker Arm Adjuster Screws (positive lock): 3/8″-24

Rocker Arm Shaft Expansion Plugs: Dorman 555-082 (45/64″) 

  • Note: The poly rocker arm shaft expansion plugs are larger than the LA shaft plugs, and the A-block plugs are not marketed through major distributors. I have researched and personally tried five different plugs, and the Dorman 555-082 is the best fit.

Spark Plug: 3/8” short-reach such as Autolite 85, Champion 63 (formerly J12Y), etc.

  • Warning: Do not install LA-type 3/4″ long-reach plugs, such as Autolite 65. They will contact the piston.
  • Note: There is a lot of misinformation about spark plugs with some people claiming A-block or Mopar engines will only run well with one brand over the other, which is inaccurate. Any reputable brand spark plug will perform just fine with a healthy A/LA ignition system.

Starter Motor: see my article on available starter motors

Thermostat: (see my cooling system article for selection and discussion)

  • 180°: Stant 45358
  • 180° High-flow: Mr. Gasket 4367
  • 195°: Stant 45359
  • 195° High-flow: Mr. Gasket 4365
    • Note: High-flow thermostats should be paired with a high-flow water pump and larger radiator for optimal utilization.

Timing Set: LA273/318/340/360

  • Cloyes C3002K (OEM-type single non-roller)
  • Cloyes C3028X (double roller w/ cam advance adjustment)
  • Cloyes 93503X9 (billet double roller w/ cam advance adjustment)

Valve Cover Retainers:

  • Poly valve cover bolt cup washers: I found that skateboard truck washers are almost identical to the early A-block washers
  • Beck/Arnley 039-6659 (2003 – 2006 Honda Element EX 2.4L, info courtesy Michael Lindsay)
    • Note: These steel retainers are larger than the early 277/318 retainers but may be of interest to some.

Valve Springs: 1.70″ installed height springs for OEM machining.

  • Many LA springs are 1.7″ installed height.
  • Always follow the cam requirement for seat and open pressures at the cam’s maximum lift.

Valve Spring Keepers: 7° or 10° matched to valve stem diameter, groove type, and retainer angle.

Valve Spring Retainers: 7° or 10° degree matched to stem diameter, springs, and keepers.

Valve Stem Seals:

  • 3/8″ Stem Positive Seal: FelPro SS72730
  • 3/8″ Stem Umbrella: FelPro SS70014

Water Pump: 

  • Use 1957 – 1969 A/LA iron pump for factory left-side intake and short pump to match A-block pulleys (Figures 1 and 2).
    • OEM Type: WP58180, TFW43030 
    • High-flow: FlowKooler 1701
      • Note: Should use a high-flow thermostat for optimal utilization.
  • Use 1970 onward aluminum pump for right-side intake but will need 1970 onward pulleys since the pump is longer than the pre-1970 (Figures 1 and 2).
    • OEM Type: WP58181, TFW43026
    • High-flow model: Tuff Stuff 1465NA
      • Note: Should use a high-flow thermostat for optimal utilization.


Poly A-block 318 Pulleys Dodge Plymouth Chrysler Mopar
Figure 1: Pre-1970 A/LA Pulley (left) and Post-1969 LA Pulley (right)

Poly A-block 318 LA Short and Long Water Pumps Dodge Plymouth Chrysler Mopar
Figure 2: A-block Poly and LA Water Pumps