Last update: 08/28/1999

John - Weber DGV - SU setup. Carbs is carbs.

My opinion- ONLY way is with the air/fuel ratio meter. Then you KNOW what's happening. For the Weber- jets are available & it's simply a matter of correcting the mixture at various loads/rpm as determined by driving & watching the meter.

The engineering in Webers is quite complex- emulsion tubes, air jets,fuel jets, neat little enrichment holes, holes in the butterflys, etc. If you want to go nuts & have fun- get all the books on theory & tuning of Webers you can find (I think I have eight..) and try to figure them out. I did pretty well with the books, lots of thinking and lots of (pricey...) little brass parts. A real "zen" process for me- probably a simple correction for an expert. It is fun but- the books were written before the availability of modern air/fuel ratio meters. The car ran "great" but without a meter- I really had no idea if I had maxed out the mixtures.

In the real world- I'll bet that with an air/fuel meter and a fuel jet change or two, you can get it running kick-ass. Or.. if you want more- read the books AND use the meter.

I have yet to check an engine that I couldn't improve the performance of with a simple tweek of a jet/needle. The meter tells you.

Don't get nuts about mixture at all speeds- it ain't gonna happen with carbs. Just check hard acceleration at wide open throttle- say pulling third gear. You want around 12-13:1 mixture.

Check mid-range cruise- say a nice 50 mph on flat, high gear, steady throttle. Strive for around 17:1.

Check idle- somewhere on the meter- 17:1 would be great but not that important- just so it runs nice and is not way off the meter.

That's it.

An engine will run on a godawful mixture. We have all have kept engines running by simply pouring gasoline down the carburetor now & then or spraying starting fluid in the hole.... That's an extreme- but it works. Just about any carb will "run", but how good? A car can be very drivable even though it is very rich/lean in places. That's where tuning comes into play. The closer you get to proper mixture at various loads/rpm- the better it runs though. Forget anyone's recommendations about jets, needles (SU), settings, etc. They are all educated guesses but YOUR engine is different- an individual.

Get the meter and KNOW what the mixture is- then go from there.

Fred Sisson