Overcoming Performance Hurdles in the Upgraded Datsun 510

The Datsun 510 has earned a legendary reputation among classic car enthusiasts as a nimble, lightweight platform with tremendous tuning potential. Known as the "poor man's BMW," this rear‑wheel‑drive sedan responds exceptionally well to modifications. However, the path to higher horsepower and sharper handling is rarely without pitfalls. Even carefully planned upgrades can introduce new problems—misfires, poor fuel economy, overheating, and driveline vibrations that can ruin the driving experience. Understanding the root causes of these issues and knowing how to correct them is essential for anyone serious about extracting the 510’s full capability without turning ownership into a constant troubleshooting exercise.

This guide examines the most common performance problems that arise after upgrading a Datsun 510 and provides practical, step‑by‑step solutions. Whether you’ve installed a high‑compression engine, swapped in a modern fuel‑injection system, or stiffened the suspension, the challenges you face are known and solvable. With the right diagnostic approach and a willingness to dial in every system, your 510 can deliver the reliable, engaging performance you built it for.

Engine Misfiring and Ignition System Headaches

Misfiring is one of the first symptoms many owners notice after an upgrade—especially when the ignition system hasn’t been updated to match increased cylinder pressure or fuel flow. A misfire not only robs power and fuel economy but can also damage the catalytic converter if left unchecked. The Datsun 510’s original points‑type ignition works adequately for a stock engine but becomes a weak link as compression ratios climb and rev limits increase.

Causes of Post‑Upgrade Misfiring

  • Spark plug gap mismatched to boost or compression. Higher cylinder pressures require a smaller gap to prevent spark blow‑out. A gap that is too wide causes sporadic misfires, especially under heavy load.
  • Ignition component wear or compatibility issues. Old spark plug wires with high resistance, a weak ignition coil, or a distributor cap with carbon tracking can all create intermittent failures. Aftermarket ignitions such as the Haltech Elite series require proper coil selection and wiring.
  • Incorrect fuel mixture. An overly rich or lean condition affects flame kernel propagation. A lean misfire is particularly damaging because it generates high exhaust temperatures.
  • Damaged or incorrect spark plugs. Using plugs with an incompatible heat range or fouling from an ill‑tuned carburetor or ECU map.

Solutions for Reliable Ignition

  • Set the spark plug gap according to the engine’s specific requirements. For naturally aspirated builds with 10:1 or higher compression, a gap of 0.028–0.032 inches is typical. For forced induction, reduce to 0.025 inches or less.
  • Upgrade to a modern electronic ignition system. Kits from Pertronix or a full aftermarket ECU with a crank trigger and direct‑fire coils eliminate points wear and allow precise timing control.
  • Replace spark plug wires, distributor cap, rotor, and coil with high‑quality, low‑resistance components. The stock 40‑year‑old wiring often has hidden resistance that only shows up under load.
  • Tune fuel delivery using a wideband oxygen sensor and a compatible gauge or ECU. Target an air‑fuel ratio of around 12.8:1 at wide‑open throttle for a naturally aspirated engine, and 11.5–12.0:1 for a turbocharged build.
  • Verify the ignition timing with a timing light. Many engine swaps require re‑curving the distributor or altering the trigger angle in the ECU.

Fuel Economy Drop‑Off and Tuning Mismatches

It’s common for a modified Datsun 510 to get worse fuel economy than a stock example, but a drastic decrease—say, dropping from 25 mpg to 12 mpg—indicates a fundamental tuning problem. Often, the fuel delivery system is not calibrated for the new engine’s volumetric efficiency, or the air‑fuel ratio is chronically rich. Poor fuel economy can also be a symptom of an improperly sized carburetor or a fuel injection map that hasn’t been optimized for cruising conditions.

Root Causes of Fuel Waste

  • Carburetor jetting too large. When upgrading to a larger carburetor (e.g., Weber 45 DCOE instead of the OEM 32‑36 DGV), the main jets, air correctors, and emulsion tubes must be selected carefully for the specific engine displacement and camshaft profile.
  • EFI mapping that lacks closed‑loop correction. Many budget standalone ECUs do not automatically trim fuel in closed loop without a wideband sensor installed, leading to a permanently rich baseline.
  • Increased engine friction or parasitic drag. Heavy aftermarket parts, larger alternators, or oversized cooling fans can consume extra power, reducing efficiency.
  • Changed driving habits. It’s natural to drive more aggressively after upgrades, which directly impacts fuel consumption.

Practical Steps to Recover Efficiency

  • Install a wideband oxygen sensor and gauge. An affordable kit from AEM or Innovate Motorsports provides real‑time feedback so you can adjust the fuel curve.
  • If running a carburetor, read the spark plug color regularly: a tan/grey deposit is ideal; black soot means rich. Adjust jetting accordingly, starting with the idle circuit, then progression and main circuit.
  • For EFI systems, configure the closed‑loop fuel trims and enable learning if supported. Spend time datalogging during steady‑state cruising and light load to fine‑tune the fuel mixture.
  • Check that the choke (if carbureted) opens fully once the engine is warm. A stuck choke enriches the mixture continuously.
  • Reduce rotating and reciprocating mass where possible: aluminum flywheels, lightweight pulleys, and removal of unnecessary accessories help the engine accelerate more freely.

Overheating: When the Cooling System Can’t Keep Up

Overheating is one of the most serious issues a modified 510 can face, and it often appears immediately after an engine swap or after adding forced induction. The original single‑row radiator and mechanical fan are marginal even for a stock L‑series engine. Once you increase power output, the cooling system must be upgraded to match the heat rejection requirements or engine damage is inevitable.

Why Upgraded Engines Run Hotter

  • Insufficient core capacity. A stock radiator has limited fin density and overall volume. High‑performance engines generate 30–50% more waste heat.
  • Airflow restriction. Aftermarket intercoolers, oil coolers, and A/C condensers stacked in front of the radiator can block airflow, particularly at low vehicle speeds.
  • Water pump limitations. The stock cast‑iron impeller water pump may not flow enough coolant at higher RPM to keep the engine cool.
  • Thermostat malfunction. A stuck‑closed or slow‑opening thermostat forces the engine to operate above the optimal temperature range.

Comprehensive Cooling Upgrades

  • Replace the radiator with a high‑performance aluminum unit. Crossflow radiators like those from Mishimoto offer increased core volume and better heat transfer. Choose a model with at least two rows of 1‑inch tubes for engines up to 250 hp.
  • Install a high‑flow water pump. A pump with a CNC‑machined impeller (such as those from Stewart Components) dramatically improves coolant circulation.
  • Use an electric fan setup with a thermostatic controller. Spal or Derale fans pull more air at idle compared to the stock belt‑driven fan, and the controller keeps the engine at a consistent temperature.
  • Add a separate oil cooler with a thermostat sandwich plate. Engine oil carries a significant portion of heat, and a cooler designed for 18‑row or larger will help stabilize temperatures during sustained high‑load driving.
  • Flush the entire cooling system thoroughly after any engine swap to remove scale and debris. Use a coolant designed for aluminum radiators (e.g., ethylene‑glycol with corrosion inhibitors).
  • Consider ducting and a sealed radiator shroud to force all incoming air through the core rather than around it. This is often overlooked but essential for track use.

Unresponsive Throttle and Intake System Issues

A sluggish throttle pedal after modifications points to problems in the intake or throttle actuation. The Datsun 510’s cable‑operated throttle can bind or stretch, and the addition of aftermarket intake manifolds or throttle bodies often introduces alignment issues. Vacuum leaks are another common culprit, especially when swapping to individual throttle bodies (ITBs) or changing the manifold gasket.

Common Sources of Throttle Lag

  • Throttle linkage binding. Aftermarket carburetors with different stud patterns or ITBs with individual return springs can create friction in the cable pull.
  • Vacuum leaks at manifold gaskets, hose connections, or the brake booster line. Unmetered air leans the mixture and reduces throttle response.
  • Faulty throttle position sensor (TPS) on EFI conversions. An incorrect TPS signal prevents the ECU from properly transitioning through idle, partial, and full throttle maps.
  • Air cleaner restriction. A poorly designed intake box or dirty filter chokes the engine at higher RPM.

How to Restore Sharp Throttle Response

  • Inspect the throttle cable for fraying or stiffness. Replace it with a modern Teflon‑lined cable if necessary. Ensure the cable has a smooth, gentle arc with no sharp bends.
  • Adjust the throttle linkage so the butterfly opens fully when the pedal is floored. A throttle stop that prevents 100% opening is a common oversight.
  • Smoke test the intake system to find vacuum leaks. Any leak around the manifold base, vacuum caps, or the brake booster can be isolated and repaired.
  • If using an EFI system, calibrate the TPS with the ECU. Set the idle position at 0% and wide‑open throttle at 100% according to the manufacturer’s procedure.
  • Ensure the air filter has adequate surface area and flows freely. A K&N or similar high‑flow panel element works well; avoid tiny “pod” filters that sit directly on the throttle body without a velocity stack.

Excessive Vibration and NVH After Suspension or Drivetrain Upgrades

Vibration is a frustrating byproduct of many 510 upgrades. Stiffer engine mounts, urethane bushing kits, and driveline components intended to improve cornering can inadvertently transmit more vibration into the cabin. In some cases, the vibration is actually a sign of an improperly aligned driveline or unbalanced rotating assemblies.

Origins of the Shake and Rattle

  • Unbalanced tires or wheels. Aftermarket wheels often require hub‑centric rings, and even minor imbalances become noticeable with stiffer suspension.
  • Engine mount stiffness. Polyurethane or solid mounts transfer engine vibration directly to the chassis, while the stock rubber mounts isolate much of it.
  • Driveshaft angle issues. When lowering the car or swapping to a different transmission, the pinion angle changes. If the engine/transmission angle and pinion angle are not within a degree or two, vibration occurs at speed.
  • Worn suspension components. Old ball joints, tie rod ends, or control arm bushings can loosen and cause wheel hop or shimmy.
  • Engine balance. An internally unbalanced engine that hasn’t been zero‑balanced with the flywheel and harmonic damper will shake, especially at high RPM.

Diagnostic and Repair Approach

  • Have all four wheels balanced on a modern dynamic balancer, and verify the tires are road‑force balanced if possible. Check for bent rims or excessive runout.
  • If engine vibration is too harsh, consider a compromise: use polyurethane engine mounts on the driver’s side and a slightly softer mount on the passenger side, or try Nismo’s semi‑solid mounts that offer a balance of strength and isolation.
  • Measure driveline angles using an inclinometer at the transmission tail shaft and the pinion flange. Adjust the pinion angle by shimming the differential or using adjustable control arms. The target is equal and opposite angles with a difference less than 1° under load.
  • Inspect and replace any worn suspension bushings with new rubber or poly units. Check that all bolts are torqued to spec and that the sway bar end links are not binding.
  • When building the engine for high RPM use, have the rotating assembly (crank, rods, pistons, flywheel, damper) balanced as a complete unit. This is critical for engines revving past 7,000 RPM.

Additional Considerations for a Reliable High‑Performance 510

Beyond the core issues above, several other systems can trip up an otherwise well‑built Datsun 510. Electrical gremlins from outdated wiring, fuel delivery starvation under high G‑forces, and insufficient braking power can all derail your enjoyment. Addressing these proactively ensures a more complete upgrade experience.

Electrical System Upgrades

The stock 510 alternator outputs around 50 amps, which may be insufficient for an electric fan, fuel pump, aftermarket ECU, and modern headlights. Upgrade to a 70‑amp or higher alternator from a Nissan Z car or a universal unit from Powermaster. Rewire the charging circuit with larger gauge wire and install a dedicated fuse box for add‑on circuits. A high‑torque starter is also a worthwhile upgrade for high‑compression engines that crank slowly.

Fuel Supply for High Output

Stock fuel lines (5/16 inch) restrict flow for builds over 250 hp. Run a dedicated 3/8‑inch or -6 AN feed line from the tank to a surge tank or a high‑pressure pump. Use a fuel pressure regulator near the engine and a return line to the tank. This prevents fuel starvation during hard cornering and ensures consistent pressure at the regulator.

Braking and Suspension Harmonics

With increased speed comes greater braking demand. Upgraded pads, slotted rotors, and a larger master cylinder (e.g., from a 280ZX) dramatically improve stopping power. As for vibration, even a perfect suspension tune can’t mask poor wheel bearings. Replace them at the first sign of play.

For detailed community knowledge and vendor support, refer to the dedicated 510 subforum at Ratsun.net, where owners share build logs and troubleshooting threads. Parts suppliers like FutoFab specialize in 510 suspension and driveline components that directly address many of the vibration and clearance issues common after modifications.

Final Thoughts on Dialing In Your Modified 510

No two Datsun 510 builds are identical, but the performance problems that follow upgrades are remarkably consistent. Engine misfiring, poor fuel economy, overheating, dull throttle response, and excessive vibration all stem from mismatched components or overlooked tuning steps. By methodically diagnosing each problem—measuring, adjusting, and verifying before making the next change—you can turn a frustrating project into a satisfying, high‑performing machine.

Start with the fundamentals: upgrade the cooling system and ignition before chasing peak horsepower. Tune fuel delivery with a wideband sensor. Balance the driveline angles. And never underestimate the importance of a clean, properly sized electrical system. When these systems work in harmony, the 510 rewards you with a driving experience that few modern cars can match—responsive, lightweight, and utterly connected to the road.