TheSamba.com :: View topic

Sat Jun 28, 2008 7:32 pm

In my 2110 (w110 Steve Tims stage1 heads 40x35, stock rockers, 8:1 CR) i have a pair of 40 IDF, when i got them they had 28 vents,and it used to run good, now i changed them to 32 and im having some trouble getting my jets right; when it is cold, i feel it doesn't have enough power and shakes a little between 1200 and 2200rpm, above that it runs well until 5000rpm, but when it gets to its normal operating temperature it starts misfiring on accelerations, and loose power, with the 28 vents i use to get 120km/h really easy on a hill coming home, now it gets there and doest accelerate more, i think my jets are wrong, i got some but now i realized they are marked wrong, what i really have is: 32 vents, 190 air, 155 main, 55 idle, before with my 28 vents i had 190 air, 120 main, 50 idle, what would be a start point for the jetting, and why do you think is misfiring when hot?, thanks.

Aitor

Sat Jun 28, 2008 8:23 pm

On duel carbs like webers I take the venturies size X 4 so
32mm X 4 = 128 so a 130 or 135 sould be good for starters

Sat Jun 28, 2008 10:06 pm

And use the same airs?

Aitor

Sat Jun 28, 2008 10:12 pm

yes use the 190 airs they should work good with the 130 mains
the 55 idles should be good also ( keep us posted )

Sat Jun 28, 2008 10:14 pm

Ill try it tomorrow, thanks!

Aitor

Sun Jun 29, 2008 7:22 pm

I couldn't find 135, so i tested some 145 i had, is better but is backfiring a lot on acceleration, between 2000 and 3500rpm, and sometimes at idle, above that is ok, but only when on operating temperature, if i do the same with the engine just after warming it up, is ok, ill try to get 135 and see what happens.

Aitor

Sun Jun 29, 2008 7:49 pm

check your idle jets one or more may be plugged.
also make sure the pump jets are working.

Sun Jun 29, 2008 8:01 pm

Sorry but English is not my first language, which are the "pump jets", the ones that works with the diaphragms?

Aitor

Sun Jun 29, 2008 8:06 pm

yep. look down the carb and work the throttle you should see a stream of fuel shoot down the bore ( car NOT running ).

Sun Jun 29, 2008 8:09 pm

Ok, is just what i tough, thanks, ill check and im going to change the jets too.

Aitor

Sun Jun 29, 2008 8:15 pm

O.K. but make sure to check the idles jets also.

Sun Jun 29, 2008 8:16 pm

Psst, y'all are skipping the fundamentals. Tell him what you check FIRST!

Sun Jun 29, 2008 8:22 pm

Please, if you know something let me know, i did all the assembly on the engine, but is the first time trying to set carbs like this, at the beginning i just setted the floats, cleaned them and that was all, I've been running them like that for 6 month and now i want to set them right, or at least closer to where they should be.

Aitor

Sun Jun 29, 2008 9:22 pm

Floats and fuel pressure.. the floats HAVE to be adjusted right.. and your jetting needs to be closer to 50 idle, 140 main, 220 air as a starting point with 32 vents in those 40mm bodies.

Sun Jun 29, 2008 9:27 pm

Thank you so much, i did the floats, but i disassembled the carbs after that, ill check them and go back to the 50 idles.

Aitor

Thu Jul 24, 2008 7:41 am

Hi, i finally had time to work on my car yesterday, after some trouble with my plug wires, i started tunning, i found, 50 idle, 145 main and 220 air, the car is way better, but when i try to adjust the idle mixture, the 3 and 4 cylinders work ok, i can make them stop firing, then turn it back until they fire, and 1/2 -1 turn more, but the 1 and 2 cylinders wont stop firing, and with the engine warmed up, like half an hour it starts popping by the carbs, and some back firing in the exhaust too, now my question is, it could be because the main jet are too big? or is something else?

Aitor