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Product Summary

HEI / Male Cap Type, Mechanical Advance Type

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    Key Specs

    MFG. Part #85603
    BrandMSD
    Cap TypeHEI / Male
    Advance TypeMechanical
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    Need To Know

    Quick and Easy Returns

    Return Policy

    MSD 85603 Details

    Boat enthusiast will be glad to see the addition of the new MSD Black Marine distributor line. Built off our tried and true billet marine distributors, the 6061-T6 aluminum housing is now hard anodized with a sleek black finish for great looks.Under the black cap you'll find a quality rotor, pickup, reluctor and adjustable weight plate assembly (where applicable). Chevy applications use a .500" QPQ coated distributor shaft joined by a melonized distributor gear while Ford models run a .531" QPQ coated shaft and cast gear. Both ensure smooth operation, superior strength and long life even when challenged by harsh marine applications.The Marine Pro-Billet Distributors have been tested by Underwriter's Laboratory and are certified to meet or exceed safety standards for marine ignition systems as set by the U.S. Coast Guard.

    Features:

  • Designed for use in marine applications with Chevy V8 automotive engines
  • Black anodized for great looks and corrosion resistance
  • Will not accept a vacuum advance canister
  • Supplied with a bolt down HEI style distributor cap and rotor
  • Weathertight connectors are used for locked and sealed connections
  • Must be used with an MSD Ignition Control
  • O-ring seals can be added to modified blocks to improve oil pressure control
  • Special oil tract improves lubrication to the distributor and cam gear
  • Nylon pads ensure smooth operation of the advance weights
  • Advance weight pins are staked and tig welded to the plate
  • Mechanical advance assembly can be locked out for crank trigger systems
  • Advance plate and weights are fine blanked from chrome moly steel and QPQ coated for friction reduction
  • Polished steel shaft is QPQ coated and guided by a sealed ball bearing and extra long sintered bushing
  • Maintenance-free magnetic pickup and precision reluctor create stable trigger signals throughout the rpm range
  • Easy-to-adjust mechanical advance with supplied springs and stop bushings
  • CNC machined billet aluminum housing and billet aluminum base with two flame arrestor holes with brass screens
  • UL Approved
  • Rebates

    Holley Fuel Up Spring Savings Event 2026

    Save 10% instantly on select products across the Holley family of performance brands during the annual Holley Fuel Up Spring Savings Event 2026. Instant rebate period runs from March 30, 2026 through April 19, 2026.

    CARB Warning

    For use on pre-1966 vehicles only

    Emissions warning: this part only legal for sale or use in California if installed in vehicles model-year 1965 or older; motorcycles model-year 1977 or older; or off-highway recreational vehicles (such as off-road motorcycles and all-terrain vehicles) model-year 1996 and older. ++any other use renders the vehicle tampered and not legal for use on California public highways (any public street or roadway, public dirt road, public park, or publicly maintained right of way open to the use of the public for vehicular travel). Violations subject to $37,500 penalty per violation per vehicle, revocation of registration, loss of use on California public right of ways, and proof of correction for tampering there are similar restrictions and penalties under federal law and the laws of all other states with penalties under federal law of up to approximately $45,268 per tampered vehicle and/or engine.

    MSD 85603 Specifications

    KEY SPECS
    MFG. Part #85603
    BrandMSD
    Cap TypeHEI / Male
    Advance TypeMechanical
    GENERAL
    Trigger StyleMagnetic
    GTIN Code085132856039
    Customer Impersonation Script