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Mod1 Camshaft - Honda GX390/Big Block Clone
.310 Lift Camshaft - Honda GX390/Big Block Clones
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Mod1 Camshaft - Honda GX390/Big Block Clone

Part Number: MOD1-GX390
Online Price: $149.99
DynoCams Mod1 Camshaft for Honda GX390 & Big Block Clone Engines
Availability: In Stock.

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Description

DynoCams Mod1 Camshaft – Honda GX390 & Big Block Clone Engines


The DynoCams Mod1 Camshaft is a highly versatile performance cam designed for Honda GX390 and big block clone engines running modified builds or stock-appearing configurations with aggressively modified, stock-base carburetors. It bridges the gap between proven baseline performance and increased top-end horsepower—making it an excellent option for racers looking to gain a competitive edge without sacrificing drivability.


Designed for Ratio Rockers

The Mod1 features a .310” lift profile engineered to work seamlessly with 1.2 or 1.3 ratio rocker arms, allowing most modified cylinder heads to achieve approximately .400” total valve lift while maintaining valvetrain stability and reliability.


Performance Characteristics

The DynoCams Mod1 Camshaft is closely related to the popular .308 grind, sharing very similar lobe separation angle, duration, and lift. In most applications, the Mod1 maintains the same strong low-end and midrange torque characteristics as the 308, while producing slightly higher peak horsepower and extending the usable power band past peak power.


These gains are subtle but meaningful—particularly on larger tracks or racing formats where RPM drop is minimal, allowing the engine to stay in the cam’s effective range longer.


Performance improvements are most noticeable when paired with ported cylinder heads and larger valves, where increased airflow allows the cam’s extended duration to translate directly into additional top-end horsepower.

Importantly, the Mod1 retains much of the drivability and predictability of the 308, making it easier to tune and race compared to more aggressive cam profiles.


Built for Durability

The DynoCams Mod1 Camshaft features a hard-welded lobe design, significantly improving wear resistance in high-RPM, high-spring-pressure environments. Due to its performance-oriented profile, upgraded dual valve springs are mandatory to ensure proper valvetrain control and long-term durability.


Recommended Supporting Components

To fully unlock the performance potential of the DynoCams Mod1 Camshaft, the following upgrades are strongly recommended:

  • 34mm Carburetor
  • Billet Connecting Rod
  • Billet Flywheel
  • Billet Rocker Arms
  • Chromoly Pushrods
  • Big Valves & Porting
    Larger valves and professional port work raise the effective power band and significantly extend top-end horsepower. Big block engines naturally produce strong low-end torque, so increased airflow does not negatively impact bottom-end performance.


Fitment

  • Honda GX390
  • Predator 420 Wedge (Non-Hemi)
  • Wildcat 460
  • Cam Boss Diameter: 16mm (.628")

Important: Camshaft-to-block and camshaft-to-rod clearance must be inspected during installation.


Technical Specifications

Engine Platform: Honda GX390 / Big Block Clone
Recommended Class: Modified
Target Maximum RPM: 7,500 RPM
Valve Spring Pressure (Intake / Exhaust): 48–50 lbs Dual Springs
Valve Lash (Intake / Exhaust): .003"

Ignition Timing Recommendations

  • Pump Gas: Not Recommended
  • Race Gas (110 Octane): 32° BTDC
  • Methanol: 36° BTDC

Recommended Compression Ratio: 12.2:1


Camshaft Timing & Lift Specifications

Specification

Intake

Exhaust

Open

57.15° BTDC

96.10° BBDC

Close

95.30° ABDC

57.95° ATDC

Lift

.309"

.309"

Centerline

108.0° ATDC

108.0° BTDC

Duration @ .050"

255.00°

259.95°

Duration @ .200"

158.50°

164.50°

Why Choose the DynoCams Mod1?

  • Excellent step up from the 308 without sacrificing drivability
  • Works well in stock-appearing modified builds
  • Optimized for ratio rocker configurations
  • Strong midrange with improved top-end carry
  • Hard-welded for durability in racing environments

FAQ

What is the DynoCams Mod1 camshaft designed for?

The DynoCams Mod1 camshaft is designed for modified and stock-appearing racing builds using Honda GX390 and big block clone engines. It provides 308-like drivability with improved top-end power.


How does the Mod1 cam compare to the 308 camshaft?

The Mod1 shares similar lift, duration, and lobe separation with the 308, but carries power further past peak RPM and produces slightly higher peak horsepower—especially on larger tracks.


Can the Mod1 camshaft be used with ratio rocker arms?

Yes. The .310 lift profile is optimized for 1.2 or 1.3 ratio rockers, allowing most modified cylinder heads to achieve approximately .400” total valve lift.


Is the DynoCams Mod1 cam street-friendly?

While more drivable than aggressive racing cams, the Mod1 is intended for competition use. Idle quality and low-RPM behavior may not be suitable for casual or non-racing applications.


What supporting components are recommended?

Upgraded dual valve springs are mandatory. A billet rod, billet flywheel, billet rocker arms, chromoly pushrods, and a 34mm carburetor are strongly recommended for performance and reliability.


What engines does the DynoCams Mod1 camshaft fit?

The DynoCams Mod1 camshaft fits Honda GX390, Predator 420 Wedge (Non-Hemi), and Wildcat 460 big block clone engines with a 16mm (.628”) cam boss.


Does this camshaft require clearance checking?

Yes. Cam-to-block and cam-to-rod clearance must always be inspected during installation.

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