Car Carburettors

Dellorto DHLA/DRLA ranges
Weber DCOE/IDA/IDF ranges

Car carburettors - Weber and Dellorto (Picasa Gallery - opens in new window)

General:  The only car carburettors overhauled /restored at JRS are the Weber and Dellorto instruments stated above.

JRS has years of experience with these carburetors and brings an engineering approach to overhaul and restoration which is not widely available and that you may not find elsewhere. Thus ultrasonic cleaning, vapour/beadblasting and replating of steelwork is the JRS way.  The Gallery has illustrations of work completed at JRS; judge for yourself.

Weber and Dellorto instruments are performance carburettors. As such they are robust units and many (although not all) have virtually infinite tuning possibilities.  However they do need particular care and attention if they are to give of their best.  Neglect, poor maintenance, dirt and corrosion can ruin their performance potential.

In terms of parts, whilst the manifold stud positioning is common to Weber and Dellorto, very little else is. In terms of operational principles, they are similar.

The following detail is based mainly on 2 choke Dellorto instruments (both side and down draft types), but a similar approach is taken when working on Weber carburetors. That said, Weber DCOEs  and IDA’s have their own idiosyncracies and these are understood and dealt with at JRS.  3 barrel Webers – IDA3C are treated as a separate group that is covered later in this Car Carburettor section.

Lastly and most importantly, the appropriate tooling is held to ensure that all work is properly completed and nothing is left to chance. This is critical, because Weber and Dellorto overhaul requires specific attention to certain aspects and the appropriate tooling is essential if this work is to be completed successfully.

Services available

Comprehensive Overhaul (CO):

Where operational efficiency is what matters most, this is the recommended JRS service.

Fuel residues build up in all carburettors over time. In cases where fuel has been left in them for a prolonged period, carburettors can become completely fouled up. This JRS/UCC service is specifically designed to return carburettors to optimum operational efficiency. The methods used are absolutely harmless yet extremely powerful: no acids or any other aggressive chemical solutions that will remove metal are used.

Method:

Carburettors are washed to remove external dirt and grime. Each carburettor is then fully dismantled. All components are cleaned and rinsed in ultrasonic baths. Following forced air drying and static fuel testing, components are inspected and the customer’s attention is drawn to anything that may require replacement.  Bearings are repacked with the appropriate greases and the carburettors are then carefully re-assembled, the correct float settings being built in. Adjustable pumps are recalibrated using Dellorto/Weber approved equipment to manufacturer’s original settings (or your own requirements).

There will be times when seized components have to be machined out, or the mixture galleries have to be opened to remove blockages.  A modern machine shop and the correct tooling is held to complete this work properly. The appropriate seating tools are available to ensure that body/jet contact areas are sound. 

On completion, the carburetors are carefully repacked and returned to you by insured carrier, together with a letter which details the work completed.

Restoration:

Where under bonnet appearance is as important as operational efficiency, this service is ideal and possibly the best value for money currently available

Method:
This is an extension of the CO (comprehensive overhaul) service detailed above. In addition to the overhaul, all components are also re-engineered (via bead/vapour blasting) to remove all corrosion before being cleaned and rinsed for a second time in ultrasonic baths. There is no material change to any of the engineered tolerances in the carburettors. The work is completed with great care, cast alloy components appear as new, brass components are repolished and external steel components are beadblasted, linished, polished and replated in BZP.

Repairs:

I see a depressing number of carburettors that come to me for repair from trade and private customers alike. The damage is caused by using inappropriate tools, carelessness and seized fittings.  Examples include-

Bypass screw.
Steel screw with O ring that happily locks in place and can defy removal.

Idle mixture screw/Needle valve
Brass part with O ring and spring which is vital for carburettor set up. The slotted head of this component can shear off leaving it stuck.

Float post repairs
A broken float post has meant a scrap cover. New covers are difficult to impossible to get. Secondhand ones are all you can get and these are in short supply.

Turnaround

Comprehensive overhaul: 10-15 working days.

Restoration: 10 – 20 working days.

Costs (twin choke instruments only) includes full manufacturers or OE overhaul kits (float valves, pump diaphragms etc) and insured return carriage

Comprehensive overhaul:   £140 per instrument.

Restoration:  £ 200 per instrument.(includes all steel replating charges)

Repairs:          are only available as part of the Comprehensive Overhaul, or Restoration services.  Repairs are an additional cost, advised after inspection of the work.

Other than any parts requirement or machining costs, the quoted price is what you pay. Manufacturer’s overhaul kits and insured return carriage are included.  Currently JRS has no VAT liability.

For comparison purposes: cost of a single new DCOE from Webcon: £329 plus carriage.

Parts