Considerations When Buying Used Webers
After review of the topics regarding Weber model variations and the types of services offered by Performance Oriented to return worn-out Webers to serviceable units you probably know that buying used Webers advertised to be in good condition may be a bit misleading regarding the knowledge level of the advertiser. Moreover the seller may have found a set of Webers on his uncle's shelf and is copying the words from a previous advertisement to sell the current set. The following is a list of topics to be explored in order to help assess those used carbs you are considering for purchase:
What are the type designations of the carbs and are they matching?
- Are they paired? (3C for the passenger side and 3C1 for the driver's side in a 911)
- Do they have "Made in Italy" on the body? If not from Italy they were made in the USA and they may suffer from fuel leakage which is why they have been sitting on a shelf. Many of the non-Italian carbs are fine but they should be taken from a running car which would indicate they are not "leakers."
- IDAs, IDAPs and IDSs may be mixed into a good pair but don't mix them with an IDTP throttle body. IDT bodies (not the same as IDTP) will work with IDAs, etc. but there is a very slight variation in the progression pattern that is worth being aware of.
What condition are they in?
- Better to be from a running car than sold from storage. Sold from storage may mean they have become corroded (due to poor storage conditions) and this will almost render them unusable or expensive to repair..
- In the course of preparing for sale the carburetors may have been sand or bead blasted to clean them up which unless performed VERY carefully will destroy zinc finishes and fill air/fuel galleries with blasting media.
- Compressed air will crush the fuel floats (not visible) and render them junk.
- Throttle shafts that are stated to be "freely rotating with no play" may be a matter of opinion. A few thousandths of radial shaft clearance WILL cause tuning issues.
- Sometimes a "rebuilt" set of carbs will have the Teflon shaft bearings replaced but this is a temporary fix and probably the Teflon bearings were not replaced on both ends of the throttle body.
- Are there broken features on the throttle body? Items such as the bosses for the jet and metering screws, safety wire tabs for the float fulcrum screws and the housings for the torsion springs at each end of the throttle body are common items to be damaged.
- Are the jet holders seized in the throttle body? How about the metering screws?
What is the jetting?
- Most likely you will want to replace the jets and venturis with those correct for your application but it would be nice to get an inventory. Of course there is the risk of jets having been drilled to a larger size than their marking would indicate. Items to ask about include:
- Main venturi size
- Main jet
- Idle jet
- Air correction jet
- Emulsion tubes
- Accelerator pump jet (long or short style)
- Common issues with the jet holders (mains and idles) and the fuel bowl drain plugs are they have been over-torqued resulting in their becoming twisted or worse yet, cracked; rendering them iffy for use.
Plan to replace the accelerator pump rods (they wear quickly and are probably worn out) and to buy a standard rebuild kit that services both carburetors.