In Reply to: Here's why... posted by WH on April 26, 2000 at 22:04:42:
The 1800 RPM idle, is because of the synchro between the two carbs is off. Use a hose and your ear get the same tone and beat the same on all 4 butterflies. Then set the idle speed.
I can't remember the jet sizes right now, if you need to know post again and I will take a look.
: : >: are the 45 sidedraft setup suitable for the >?street?
: : Before smog rules intervened, the TI setup on the BMW 4 cylinders (2000TI 4-door, 1800 TISA, etc.) used 45DCOE's with 38mm venturis, lumpy cam, higher compression, stock cast iron exhaust manifold (without thermal reactor stuff, similar to TII manifold), mechanical-only distributor.
: : I have a complete 2000TI motor, and I set up the 45DCOE's on my stock 2002 motor-- had to fiddle with the jetting, and it's still not quite right, but there's plenty of flexibility in the Weber design. You can swap out the main and aux venturis, all jets, accelerator pump, etc.
: : Incidentally, I can't get a smooth idle below 1800 RPM (then again I've only tried a few jet combinations)--any suggestions from sidedraft experts out there?
: : Mike
: First off the 2000Ti came with 40PHH solexes not 45 dcoes. The (200) 1800tisa's were built with one purpose in mind, homologation for racing purposes. Most of these cars would be on the track competing, that's why they used the 45 dcoe setup. It would be legal to run those carbs in racing trim.... Very smart when you have to compete against 1600 GTA Alfa's with twin overhead cams and twin spark plugs etc.
: For street use on a 2 liter motor use 40 dcoe's --the 45's are way overkill. If you are using 38mm venturies or smaller the 40 dcoe will give you better response and slightly higher torque at the low and mid rpm level due to increased intake air speeds, even with up to a 300 degree cam.
: The advantage of the 45 dcoe will not be seen till very high rpm (7000 rpm+), because it will simply flow more air to the engine. Most street engines never see that high a rpm for any length of time.