News

SU fuel pumps and repair parts on a workbench
How to Test an SU Mechanical Fuel Pump (AUF 700 and AUF 800)
How to tell whether your SU mechanical fuel pump is at fault: the flow check at the carburettor, plus the vacuum and pressure figures an AUF 700 or AUF 800... Read more...
SU electric fuel pumps and repair parts on a workbench
SU Electric Fuel Pump Specifications: L, HP, AUF 200 and AUF 300 Compared
Flow rates, line pressures, pipe sizes and mounting positions for the SU L, HP, AUF 200 and AUF 300 electric fuel pumps, plus the dual AUF 400 and AUF 500. Read more...
SU HS carburettor stripped on the workshop bench
The SU Piston Drop Test: How to Check for a Sticking Piston
A sticking SU piston causes stalling, erratic running and poor power. Here is how to check the piston falls freely, how to centre the jet, and the timed drop test... Read more...
SU carburettor parts laid out on a workshop bench
SU Damper Oil: Which Oil to Use, How Much, and Why It Matters
The SU piston damper is the reason an SU accelerates cleanly. Here is which oil to use, the correct level for standard and ball-bearing suction chambers, and what happens when... Read more...
Common SU Carburettor Problems — Symptoms, Causes and Fixes
Flooding, flat spots, black smoke, poor idle — SU carburettor problems have recognisable symptoms and straightforward fixes. Our diagnostic guide covers the most common faults and the parts that cure them. Read more...
Preparing Your Classic Car's SU Carburettor for Autumn and Winter
As temperatures drop, your SU carburettor needs attention. Learn how to prepare your classic car's fuel system for autumn and winter — from damper oil to float chambers and jet settings. Read more...
Inside a Real Refurbishment: Bringing a Pair of HD8 SU Carburettors Back to Life
This post follows a pair of HD8 SU carburettors through our workshop — from arrival to completion. The carburettors came from a 4.2 litre Daimler Sovereign, a car that deserves nothing less than a proper professional rebuild. The Car The 4.2 litre Daimler Sovereign is one of the most refined expressions of the Jaguar XK engine — a straight-six that powered some of the most important British cars of the post-war era. In Sovereign specification it was tuned for smooth, effortless torque rather than outright power, and the twin HD8... Read more...
New Service: SU Fuel Pump Refurbishment
We are pleased to announce that we now offer a full professional refurbishment service for SU electric fuel pumps, alongside our existing carburettor rebuild service.The SU electric fuel pump is a robust and elegant piece of engineering, but after decades of service — and particularly with the increased use of ethanol-blend fuels — the internal components inevitably wear. A pump that clicks but delivers poor pressure, or one that has stopped working entirely, is nearly always repairable, and a properly rebuilt pump will outlast a cheap pattern replacement by a... Read more...
Classic Car Winter Prep: Getting Your SU Carburettors and Fuel Pump Ready
Autumn is the right time to give your classic car a proper going-over before the cold weather sets in. Whether you are planning to store the car through winter or intend to keep driving it, getting the fuel system in good shape now will save you problems in spring — and possibly prevent a breakdown on a cold, wet morning.Check the CarburettorsDashpots and OilIf you have not changed the dashpot oil since the last service, do it now. SU carburettors rely on a hydraulic damper to control mixture enrichment under... Read more...
How to Tell If Your SU Fuel Pump Needs Rebuilding
An SU fuel pump rarely fails without warning. In most cases there are clear signs that something is wrong before the car lets you down — if you know what to listen and look for. Here is a straightforward guide to diagnosing a failing SU electric fuel pump.The SymptomsContinuous Rapid ClickingA healthy SU pump clicks steadily when starting and slows to an occasional tick once the float chambers are full. If your pump clicks rapidly and continuously while the engine is running, it is working harder than it should. This... Read more...
The SU Fuel Pump: How It Works and Why It Fails
The SU electric fuel pump is one of the most dependable pieces of engineering on a classic car — but like any component that has been in service for decades, it has its weak points. Understanding how the pump works makes it much easier to diagnose problems before they leave you stranded.How the SU Electric Fuel Pump WorksThe SU pump is an electromagnetic diaphragm pump. At its heart is a solenoid coil surrounding a soft iron armature. When power is applied, the solenoid pulls the armature and with it a... Read more...
Full Rebuild: Twin SU Carburettors from an Austin Healey 3000
Full rebuild of twin HD8 SU carburettors from an Austin Healey 3000 — strip down, ultrasonic clean, spindle bearing overhaul, and all-new internals. See the before and after. Read more...
How to Balance Twin SU Carburettors: A Step-by-Step Guide
If your classic British car runs twin SU carburettors, getting them balanced is one of the most satisfying — and most important — tuning jobs you can do. Unbalanced carbs cause rough idling, uneven throttle response, poor fuel economy and excessive wear. The good news is that with the right approach it's a straightforward afternoon job, even for a relative beginner. This guide covers the complete process for cars fitted with twin SU carburettors, including the HS, HIF and H-series types fitted to MG, Triumph, Austin Healey, Jaguar and countless... Read more...
SU Carburettor Tuning Guide
Getting Your SU Running Perfectly A correctly tuned SU carburettor is a delight — responsive, smooth, and efficient. An incorrectly tuned one can be frustrating to diagnose. The good news is that SU carburettors are designed to be adjusted with simple tools and no specialist equipment. This guide walks through the complete tuning procedure for HS and HIF series carburettors. Before starting, make sure the carburettor has been fully serviced or rebuilt with new service parts. Attempting to tune a worn carburettor is largely futile — the variables introduced by... Read more...
Which SU Carburettor Parts Fit My Classic Car?
A Quick-Reference Guide by Vehicle One of the most common questions we get asked is: "Which SU carburettor parts do I need for my car?" The answer depends on the exact carburettor specification fitted, which can change within the same model by year, market and engine. This guide lists the typical original SU fitments for popular British classics, taken from the SU factory application listings. For the exact parts, the quickest route is Find My Kit. Pick your car, year and carburettor, and it shows the specification number and every... Read more...
Common SU Carburettor Problems and How to Fix Them
The Most Common Faults — and What Causes Them SU carburettors are robust, long-lived units that will run for decades with minimal attention. But when something does go wrong, the symptoms can be confusing. This guide covers the faults most commonly encountered on HS and HIF series carburettors — what causes them, how to diagnose them, and what to do about it. 1. Rich Running (Black Smoke, Sooty Plugs, High Fuel Consumption) Symptoms Black smoke from the exhaust, sooty or oil-fouled spark plugs, excessive fuel consumption, rough idle, strong petrol... Read more...
How to Rebuild an SU Carburettor: Step-by-Step Guide
Everything You Need to Know Before You Start Rebuilding an SU carburettor is one of the most satisfying jobs on a classic car — and one of the most rewarding. A properly rebuilt SU will reward you with smooth, reliable running and accurate fuel delivery. The good news is that SU carburettors are elegantly simple by design, and a full rebuild is well within the capability of any home mechanic with patience and the right parts. This guide covers the rebuild process for the HS series carburettor, which is the... Read more...
How to Identify Your SU Carburettor
HS2, HS4, HIF44 — What Have You Got? If you're working on a classic British car, chances are it's fitted with an SU carburettor. SU (Skinners Union) carburettors were fitted to millions of vehicles from the 1930s through to the 1990s — from the humble Mini to the Jaguar E-Type — and understanding exactly which type you have is the essential first step before ordering any parts. This guide will walk you through how to identify your SU carburettor by type, size, and application. The SU Carburettor Family SU produced... Read more...