Why the Weber 32/36 Carburetor Is a Top Upgrade for Your Datsun 510

The Datsun 510, often called the "poor man's BMW," is a lightweight sedan with a rev-happy L-series engine. One of the most effective bolt-on modifications for unlocking its potential is swapping the stock Hitachi or Solex carburetor for a Weber 32/36 DGV progressive two-barrel carburetor. This upgrade can deliver a verified gain of up to 12 horsepower—and often more when paired with a free-flowing exhaust and a proper distributor tune. The Weber 32/36 offers superior fuel atomization, easier tuning, and better throttle response across the rev range. In this guide, you'll learn how to install, adjust, and dial in this carburetor for maximum performance and reliability.

Tools and Materials Needed

Before starting, gather all necessary tools and parts. Having everything on hand will prevent unnecessary trips to the hardware store and ensure a smooth installation.

  • Weber 32/36 DGV carburetor kit (e.g., from Redline or Weber Performance)
  • Intake manifold adapter plate (if your 510 has a Lynx or Cannon manifold, you may need a specific adapter)
  • Carburetor base gasket (paper or composite, matches intake port pattern)
  • Carburetor mounting studs and nuts (often included with the kit)
  • Fuel line with correct diameter hose and clamps (5/16" fuel hose recommended)
  • Air filter assembly (Weber foam or K&N style)
  • Throttle linkage kit (Weber makes an adapter for Datsun L-series throttle cables)
  • Vacuum gauge (essential for tuning idle mixture and synchronizing barrels)
  • Socket set (8, 10, 12, 14 mm), wrenches, screwdrivers (flathead and Phillips)
  • Torque wrench (to avoid over-tightening carburetor base nuts)
  • Shop towels and carburetor cleaner for cleaning gasket surfaces

Understanding the Datsun 510's L-Series Engine

The Datsun 510 originally came with either an L16 or L18 engine (depending on year and market). Both share a crossflow head design with a single-plane intake manifold. The stock Hitachi DCH-340 carburetor is a two-barrel progressive unit, but its tiny venturis and restrictive air bleeds limit airflow above about 5500 rpm. The Weber 32/36 DGV has a primary venturi of 24 mm and secondary of 27 mm (actual venturi size: 32 mm primary, 36 mm secondary), providing significantly more flow capacity without overwhelming the L-series' mild camshaft. With proper jetting (typically main jets around 135-145 primary and 150-160 secondary, air correction jets 170-180), the Weber can support up to 130-140 hp on a well-tuned L18—enough for a noticeable street performance upgrade.

Pre-Installation Checks

Before you touch a wrench, ensure your Datsun 510 is mechanically sound. A carburetor upgrade won't fix worn rings, a blown head gasket, or a clogged fuel tank. Perform the following checks:

  • Compression test (all cylinders above 120 psi and within 10% variation).
  • Check for vacuum leaks in the existing intake system (cracked hoses, loose manifold bolts).
  • Inspect fuel line condition and replace any rubber sections older than 5 years.
  • Verify the mechanical fuel pump delivers 3–4 psi at idle (Weber 32/36 requires 2.5–4 psi; higher pressure can overcome the float valve).
  • Disconnect the battery negative terminal to prevent accidental shorting.

Step 1: Remove the Old Carburetor and Manifold

If your Datsun 510 still has the original Hitachi carburetor and intake manifold, you can either reuse the manifold (with an adapter plate) or upgrade to a Weber-specific manifold (Lynx, Cannon, or Offenhauser). For this guide, we assume you are using the stock manifold with an adapter plate.

  1. Remove the air cleaner assembly. Unclip the top cover and lift off the entire unit. Disconnect the hot air tube from the exhaust manifold if present.
  2. Disconnect fuel lines. Use a flare nut wrench on the steel line fitting at the carburetor; have a rag ready to catch spilled fuel.
  3. Disconnect vacuum lines. Label each line: distributor advance, PCV valve, brake booster (if equipped), and any emissions hardware. Later you may delete emissions, but for now keep track.
  4. Disconnect throttle linkage. Remove the clevis pin connecting the throttle cable to the carburetor lever. Unclip the return spring.
  5. Unbolt the carburetor. Remove the two 12mm nuts securing the carburetor to the manifold. Lift the carburetor straight up—watch for any gasket material that may stick.
  6. Remove the intake manifold (optional). If you plan to install an adapter plate or a new manifold, now is the time. Unbolt the eight 12mm or 14mm bolts holding the manifold to the head. Carefully pry it loose; do not damage the gasket surface.

With the old parts off, thoroughly clean the intake manifold mounting face using a plastic scraper and carburetor cleaner. No gasket residue should remain. If reusing the stock manifold, also inspect the internal runners for carbon deposits—clean them with a brush and solvent.

Step 2: Install the Adapter Plate and Weber 32/36

Weber 32/36 kits for Datsun 510 typically include an adapter plate that mates the Weber's two-barrel flange to the stock manifold's "square" flange pattern. Follow these steps:

  1. Place the base gasket on the manifold flange. Make sure the holes align perfectly. If using a layered gasket, peel off both paper surfaces.
  2. Mount the adapter plate on top of the gasket. Use the supplied studs or bolts; hand-tighten only at this stage.
  3. Install the Weber carburetor base gasket on top of the adapter plate. This gasket is usually a thin paper or composite piece specific to the Weber 32/36.
  4. Position the Weber 32/36 on the adapter plate, aligning the throttle linkage side toward the driver's side (left-hand drive models). The secondary throttle lever should face the firewall or the front depending on your kit; refer to the instruction manual.
  5. Secure the carburetor with the four nuts (or studs). Tighten in a cross pattern to 90–100 in-lb (10–12 Nm). Do not overtighten; the aluminum carburetor body can distort.
  6. Reconnect the fuel line. Use a 5/16" fuel hose with EFI-style clamps. Connect to the Weber fuel inlet (usually on the front side). If your stock line is steel, you may need a short rubber hose with a compression union.

Adapter Plate Considerations

Some aftermarket intake manifolds (like the Cannon DGV520) bolt directly to the Weber 32/36 without an adapter. If you have a Cannon or similar, skip the adapter and mount the carb directly with a gasket. The adapter adds about 1/2" of height, which may require a shorter air filter or modifying the hood's inner reinforcement. Measure clearance before final assembly.

Step 3: Connect Throttle Linkage

The Datsun 510's throttle cable is short and routes along the inner fender. The Weber kit usually includes a linkage adaptor that clamps onto the carburetor's throttle lever.

  1. Attach the throttle cable end to the Weber throttle lever using the supplied clevis and pin. There may be multiple holes; choose the one that provides full throttle travel without binding.
  2. Adjust the cable length by loosening the lock nut on the cable sheath where it enters the pedal bracket. You want a small amount of free play (1-2 mm) before the lever begins to move.
  3. Install a throttle return spring between the carburetor lever and a solid bracket on the intake manifold or firewall. Use a high-tension spring rated for Weber carburetors to ensure the throttle snaps closed when released.
  4. Test full throttle. With the engine off, press the accelerator pedal to the floor. The Weber throttle plate should open fully (90 degrees). If it stops short, lengthen the cable or reposition the lever.

Step 4: Vacuum Lines and Distributor Advance

The Weber 32/36 has two vacuum ports: one on the primary side (ported vacuum, above throttle plate) and one on the manifold side (full manifold vacuum). For a standard Datsun 510 distributor (points or electronic), connect as follows:

  • Distributor vacuum advance: Connect to the ported vacuum port (small brass tube on the side of the primary barrel). This provides vacuum only when the throttle is open slightly, giving better idle stability.
  • PCV valve: Connect to a manifold vacuum source. If your Weber base has a large port on the front, use that. Otherwise, tee into the brake booster line (if equipped) or use a dedicated port on the intake manifold.
  • Brake booster: Connect to manifold vacuum via a one-way check valve. The stock booster line may require a fitting adapter.
  • Vacuum advance for emissions: If your Datsun still has a vacuum switching valve (VSV) or thermal sensors, you can delete them for simplicity. Otherwise, retain them according to factory diagrams.

Plug any unused vacuum ports on the carburetor with rubber caps.

Step 5: Preliminary Adjustments and Start-Up

Before starting the engine, set the Weber to baseline settings:

  • Idle mixture screw: Turn it clockwise until lightly seated, then back it out 1.5 turns (this is a safe initial setting).
  • Idle speed screw: Back it off so the throttle plate is just slightly open (the linkage should not hold the plate open when the pedal is released).
  • Fast idle cam (choke): If your carburetor has a manual choke, set the choke pull-off to factory spec (usually 0.060" gap between choke plate and bore when cold).

Fill the float bowl by briefly cranking the engine with the accelerator pedal floored (do not start). This allows the fuel pump to prime the carburetor. After a few seconds, release the pedal and try to start the engine. It may take several attempts. Once it fires, let it idle at 1500-2000 rpm for 2-3 minutes to stabilize. Then reduce speed to baseline idle (around 800-900 rpm).

Step 6: Fine-Tuning with a Vacuum Gauge

Proper tuning is essential to realize the 12 hp gain. A vacuum gauge is the best tool for setting idle mixture and checking overall engine condition.

  1. Connect the vacuum gauge to a manifold vacuum port (not ported vacuum). A T‑fitting on the brake booster line works well.
  2. Warm the engine to operating temperature (thermostat opens, radiator fan cycles).
  3. Set idle speed to 850-900 rpm using the idle speed screw.
  4. Adjust idle mixture. Turn the mixture screw clockwise (lean) until engine speed drops, then turn counterclockwise (rich) until speed peaks. Find the point of highest vacuum (usually 18-20 inHg on a healthy L-series). If the gauge needle is steady, the mixture is good. If it wanders, check for vacuum leaks.
  5. Fine-tune the fast idle if your carburetor has a choke. Set the fast idle cam to around 1500 rpm when cold.
  6. Adjust the secondary barrel synchronization. On Weber 32/36, the secondary is progressive (opens after primary reaches about 60%). There is no adjustment screw for secondary opening point—it's mechanical. However, you can check that the secondary throttle plate closes fully at idle.

Jetting Considerations

Weber 32/36 carburetors come with standard jetting from the factory, but your Datsun 510 may require different jets depending on elevation, camshaft, and exhaust. Typical L16/L18 jetting for sea level:

  • Primary main jet: 135-140
  • Secondary main jet: 150-160
  • Primary air correction jet: 170-180
  • Secondary air correction jet: 170-190
  • Idle jet: 55-60 (primary only; secondary idle circuit is fixed)
  • Enrichment jet (power valve): when present, use 60-70

If your engine runs lean (hesitation, high EGT), go up 5 jet sizes. If rich (sooty plugs, poor fuel economy), go down. Refer to the Weber tuning guide for detailed jetting charts.

Step 7: Final Checks and Test Drive

After tuning, perform these final steps:

  • Check for fuel leaks. Inspect all hose connections and the carburetor base gasket. Tighten if necessary.
  • Reinstall the air filter. Use a low-restriction filter to maximize airflow. K&N or Weber foam filters are common.
  • Reconnect the battery. Reset the idle mixture and speed if necessary.
  • Road test. Drive gently at first, then do several full-throttle accelerations from low rpm. The Weber 32/36 should provide crisp throttle response and a noticeable pull above 3000 rpm. You should feel the secondary barrel open around 3800-4000 rpm.
  • Check spark plugs. After a few wide-open-throttle runs, read the plugs. They should be light tan for an optimum mixture. Dark/sooty indicates rich; white/grey indicates lean.

Expected Performance Gain and Real-World Results

Installing a Weber 32/36 on a stock L16 or L18 typically yields 10-15 hp at the wheels, with the largest gains in mid-range torque. The 12 hp figure often quoted by enthusiasts is conservative; many report a 15-20% increase in peak power when combined with a free-flowing exhaust (2.25" pipe with a quiet muffler). The throttle response improvement alone makes the car feel much quicker. On a chassis dyno, a well-tuned Weber 32/36 on an L18 can produce 100-105 whp versus the stock 85-90 whp. For reference, Datsun 510 community dyno results confirm this gain.

Potential Pitfalls and Common Issues

Fuel Pressure Too High

The Weber 32/36 uses a float valve that can be overwhelmed by fuel pressure above 4.5 psi. If you have a high-output electric fuel pump, install a fuel pressure regulator and set it to 3 psi. Symptoms: flooding, rich idle, fuel smell, poor mileage.

Vacuum Leaks

Even small leaks at the base gasket or adapter plate can cause lean misfires and poor idle. Use a thin coat of gasket dressing (not silicone) on paper gaskets. After installation, spray carburetor cleaner around the base while engine idling; if rpm changes, you have a leak.

Secondary Not Opening

The Weber 32/36 has a mechanical secondary. If the throttle linkage is too tight or the secondary return spring is too strong, the secondary may never open fully. Check by manually moving the secondary lever while the primary is fully open—it should rotate smoothly.

Choke Sticking

Manual chokes can stick in the closed position, causing flooding when hot. Use a cable with a smooth action and lubricate the choke linkage periodically. Electric choke models (32/36 DGAV) are more reliable but require a constant 12V supply.

Maintenance Tips for Long-Term Reliability

  • Clean the Weber's idle jets and emulsion tubes every 12 months if using ethanol-blended fuel. Gasoline with ethanol can leave deposits in small passages.
  • Replace the fuel filter frequently (every oil change) to prevent debris from entering the carburetor.
  • Check the throttle linkage for wear annually; replace nylon bushings if sloppy.
  • Adjust the valve lash on your L-series every 6,000 miles; tight valves can cause poor idle that mimics carburetor problems.
  • Store the car with a full tank of fuel stabilized to avoid gum formation in the carburetor.

Conclusion

Installing a Weber 32/36 carburetor on your Datsun 510 is one of the most rewarding modifications you can make. With careful installation, proper jetting, and a vacuum gauge, you can achieve a reliable 12 hp gain and a much more responsive engine. The process is straightforward for anyone with basic mechanical skills, and the upgrade transforms the 510 into a genuinely entertaining driver's car. For further resources, consult the official Weber DGV manual and the Ratsun.net Datsun community forum for model-specific jetting advice.