If you’re tuning timing on GM HEI distributors, a quality advance curve kit helps you dial in spark at the right RPM range. These kits let you adjust the rate of ignition advance with spring sets and center plates, so you can optimize throttle response, power, and fuel efficiency. This guide highlights five popular options and explains who each is best for, plus practical buying considerations. Whether you’re building a street machine, a showroom restoration, or a competitive hot rod, selecting the right kit matters for reliable performance and drivability.
| Product | Best For | Key Benefit |
|---|---|---|
| Allstar Performance ALL81300 HEI Advance Curve Kit | GM HEI distributors from ’74-’79 | Includes two weights, center plate, color-coded springs, nylon bushings, instructions |
| Moroso 72310 Distributor Advance Recurve Kit | General GM HEI tuning | Compact package with adjustable timing curve options |
| Moroso 72300 Advance Curve Kit, Fits GM HEI Distributors | Precise RPM-based timing control | Three sets of springs with built-in stop for reliable adjustments |
| HEI Advance Curve Kit 72300 for GM HEI Distributors | GM V6/V8 engines (Chevy, Pontiac, GMC, Cadillac, Buick) | Three spring stiffness levels for fast/ultra-fast/extreme-fast curves |
| 72300 ALL81300 HEI Advance Curve Kit Ignition Timing | GM HEI distributors across multiple brands | Three-spring set and broad compatibility with GM V6/V8 engines |
Note: The above table summarizes core compatibility and benefits. For each product, review the included components and installation instructions to ensure compatibility with your distributor model and engine setup.
Allstar ALL81300 HEI Advance Curve Kit
The Allstar ALL81300 kit is designed for GM HEI distributors from model years 1974 to 1979, excluding computer-controlled units. It includes two weights, a center plate, three sets of color-coded springs, two pairs of nylon bushings, and full instructions. Best for classic muscle cars and early HEI setups where a straightforward mechanical advance tune is needed. Choose this if you want a comprehensive, ready-to-install kit with clearly labeled spring options. A potential limitation is that it may not fit electronically controlled HEI distributors without modification.
Moroso 72310 Distributor Advance Recurve Kit
The Moroso 72310 is positioned as a compact recurve option for GM HEI distributors. Its product notes emphasize practical fit and vehicle specificity. This kit is better for builders seeking a lean package with flexible timing adjustment options without the bulk of more feature-rich sets. Best for straightforward tuning in vehicles where space or simplicity is a priority. A caution is that the description focuses on packaging and fit type rather than detailed timing curves, so verify compatibility with your exact engine setup before purchase.
Moroso 72300 Advance Curve Kit, Fits GM HEI Distributors
This Moroso 72300 kit targets full RPM-based spark advance optimization. It features three sets of advance springs to adjust the rate of spark advance and a built-in stop to prevent the adjustment screw from backing out. Best for enthusiasts who want precise centrifugal timing control across rpm bands. It’s a solid choice for tuned performance, but ensure the kit is compatible with your specific GM HEI distributor model to avoid fit issues.
HEI Advance Curve Kit 72300 for GM HEI Distributors
Designed for GM HEI distributors across Chevrolet, Pontiac, GMC, Cadillac, and Buick V6/V8 engines, this kit provides three spring stiffness levels to fine-tune ignition timing. It enables precise control over initial, mechanical, and vacuum timing to meet different driving needs, from daily commuting to performance driving. Best for multi-brand GM builds that demand a consistent curve across engines. A potential limitation is that the listing emphasizes compatibility rather than included hardware specifics, so check the exact contents before buying.
72300 ALL81300 HEI Advance Curve Kit
The 72300 ALL81300 kit combines features common to both the Allstar and Moroso lines, focusing on HEI distributors used for Chevy, Buick, Cadillac, Pontiac, and GMC. It highlights adjustable ignition curves through three stiffness spring sets to tailor power delivery. Best for engines requiring a broad, adaptable curve across V6 and V8 configurations. A note of caution: ensure the kit’s built-in compatibility with your specific distributor model to avoid mounting or clearance issues during installation.
Buying Guide: How To Choose The Right Distributor Advance Curve Kit
What engine family are you tuning? Most kits target GM HEI distributors; verify your year, model, and whether your distributor is computer-controlled or mechanical. If you rely on broad torque across RPM ranges, choose a kit with multiple spring sets and a built-in stop to prevent unwanted screw movement.
- Vehicle goals: Street daily driver, weekend racer, or restoration—choose a curve kit that aligns with your performance targets.
- Distributor compatibility: Confirm model year range and whether your unit is GM HEI, V6, or V8, and ensure the kit’s springs and weights fit without modifications.
- Adjustment range: More spring options translate to finer control. Look for three or more stiffness levels.
- Installation clarity: Kits with complete instructions and labeled components reduce installation time and error.
- Durability: High-quality bushings and robust stops minimize wear and misadjustment over time.
Frequently Asked Questions
- What is an advance curve kit used for?
- Can I install a GM HEI kit on any HEI distributor?
- Why are there multiple spring sets?
- Is a built-in stop important?
- What should I check before buying?
It tunes the rate of spark timing advance as engine RPM rises, improving throttle response, power, and efficiency.
Most kits are designed for GM HEI distributors, particularly model years listed by the manufacturer. Always verify compatibility with your specific distributor and engine.
Different spring sets change the speed at which ignition timing advances. Stiffer springs usually yield faster timing at higher RPMs, while softer springs delay it for smoother idle and low-end power.
Yes. A built-in stop prevents the adjustment screw from backing out, maintaining the selected curve and preventing unintended timing changes.
Confirm distributor compatibility, engine type (V6/V8), and whether the kit’s curve aligns with your performance goals. Ensure included components match what you need for tuning.