Page last updated 16 August, 2010
Weber 40 DFi Carburettor (similar to 38 DGAS) unusual problem

Information kindly provided by John Stack

Just some freebie tech info for your site if you wish - it concerns rebuilds of the WEBER 40 DFi - 5
and the same principle/problem, may apply to the WEBER 38 DGAS as fitted to the m-series.

The 'mounting flange/sandwich plate' compresses over time. in this case, its' a 40 DFi - 5 from a '73 capri RS 3.1 being re-jetted/rebuilt for my taimar.

In any resto, check the carburettor mounting flange for trueness. they warp over time. hence the photos attached - where warpage occurs, there is naturally,
a if you smell petrol and cannot find the source, remove the carb and check the flange.

Machine as necessary...(1.5 mm + in this case) - and if warped, it is good practice to replace the sandwich plate/gasket also. i am now checking for manifold-flange trueness.

I'm just sending mine off to be machined and felt that in any post-rebuild start-up, errors in ignition timing could send fuel through the flange on full choke as the crankcase re-circulation valve may close off in the context above.

Red area shows warped area of carb base