Vacuum controlled main-flow adjusters . . . opinions.

Post by **wasserleaker** » 15 Jun 2007, 20:23

anyone using a vac. controlled flow adjuster instead of the fixed flow type? any advantages? seen a couple of the vac. ones on V8 range rover gas conversions [ orange plastic 'ecomax' contraption] alters the flow at different revs/vacuum levels for better economy, supposedly, wondered if there's anything in it.

Post by **NewarkNutter** » 16 Jun 2007, 07:35

The quantity of gas is always controlled by vacuum, or more accurately depression. The more you open the throttle, the higher the engine revs, then the greater the depression in the ventury and the more gas flows. This is the same for all carburettors.
What I think you may have seen is a closed loop system where the flow is adjusted electronically to correct the carburetion. The system uses an oxygen sensor in the exhaust and adjusts the mixture to give correct and full combustion through all ranges and loads, at least in theory at any rate.
This type of system is, I believe, normally fitted to later vehicles which have this type of set up as standard, i.e. ones with lambda sensors and cats. There probably isn't any point going to the trouble and expense of fitting one of these systems to our aged heaps.

Having said that I have no direct experience of closed loop systems as everything I have owned/run on LPG has been ancient.

Andy

Post by **toomanytoys** » 16 Jun 2007, 11:58

I fitted a vac solenoid type to my old DG... it didnt really benefit it much.. only bonus was I could see what the mixture was doing as there was a 3 led display that said weak, ok, rich... I felt the thing didnt rect fast enough... so sometimes there was a pulse in the power as it went "oh, its rich, i'll close the valve.... oh its lean, i'll open the valve...." and so on...

Better off with a stepper motor one if you really must... but I reckon a well set up open loop does just a s well..

Post by **wasserleaker** » 16 Jun 2007, 18:43

thanks for the replies!