Where to find help when you want to change major units on your CF - engine, transmission, brakes etc. - or upgrade earlier models to later specifications.
Post Reply

Weber carb

Post by Chorky » Thu Sep 28, 2017 4:28 am
Joined: Mon Sep 18, 2017 8:53 am
Posts: 1
Hello there,

I have the standard down draught weber 34ICT however it has a very bad flat spot.

Does anyone know of a "bolt on" option which I could use to up grade.


Greeting from the Land of the long white cloud (NZ)

Re: Weber carb

User avatar
Post by Phil Bradshaw » Club admin » Thu Sep 28, 2017 12:45 pm
Joined: Sun Sep 02, 2012 7:15 pm
Posts: 3462
A very bad flat spot isn't necessarily a problem with the carburettor ... and often isn't!

Troubleshoot list -

Check valve clearances (Vauxhall OHC engine, Opel CIH if early 20S with solid valve lifters).

Check valve timing.

Check ignition system including timing at idling speed with vacuum advance disconnected and hose plugged. With Delco D300 distributor with contact breakers pay particular attention to dwell angle - 49-51 degree for distributor 9977151 (stamped on body), 35-37 degree for all other D300 distributors.

Check for air/vacuum leaks around the intake manifold, brake servo and lines; check security of carburettor on manifold, insulator and gasket for leaks (and heat shield gasket on Opel CIH).

Check air filter element; renew if fouled or missing.

Check operation of air cleaner Air-Vac system if fitted (larger air cleaner with hot air hose to exhaust manifold oven): should maintain air intake temperature above 30C at idling speed at ambient 15-20C, engine thoroughly warmed up.

Check fuel pump delivery - 0.14-0.24 bar (2-3.5 psi) for Vauxhall OHC, 0.2-0.25 bar (2.8-3.7 psi) for Opel CIH. Check pump screen filter and any line filters fitted which could restrict flow.

If no faults found then try throwing a service kit at the carburettor to deal with leaky throttle spindle seals, worn float needle valve, tired body gasket, erratic or restricted idling and accelerator pump circuits.

Service kit to cover the 34ICT is available from Fast Road Cars or Dellorto. Other parts also are available from both suppliers.
  • What is real is not the external form but the idea, the essence of things. Constantin Brâncuși

Re: Weber carb

Post by tctor68 » Fri Sep 29, 2017 10:40 pm
Joined: Fri Dec 20, 2013 2:37 am
Posts: 304
I still have that carb on mine.
I had a service kit fitted and set the float level.
Put a more powerfull coil and electronic ignition.
K&n air filter and freeflow exhaust.
The engine pulls very well and not missed a beat for a few years now :thumb:

Persist with the carb and check the rest out like what Phil says and it will be fine.


Post Reply

Return to “Conversions and modifications”