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sounds like the idle air screws are in too far
 

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just my opinion but spitting like I heard on your video is common on webers that are not tuned correctly. find the threads on tuning--starting with checking timing, clean plugs, be sure the floats are set correctly, make sure the throttle plates are syncronized, setting idle at 800 to 900 rpm and dialing in the idle air screws. The jets could be wrong--but I would walk through the tuning sequence first. Are they older webers or the newer webers? the type (tipo) will tell you that. On the older webers the air adjusters sweet spot is out 3/4 to 1 turn--the new ones adjust out more--
 

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Tim
sounds like your close but several little things can be a little off. a quick search found this thread with very good technique from Gordon. http://www.alfabb.com/bb/forums/carburetors-fuel-injection/147485-i-rebuilt-40-dcoe-27-now-what.html

I suspect your throttle plates are not exactly synched--and then you need to fine tune the air adjusters but I can't find a good thread on setting them up. A needle used in the throttle observation port to insure the throttle plates are in exactly the same position will help get the throttles synch'ed and appears to work a as well as listening to a hose on the intake of the throttle bore plus is less subjective. somewhere on the bb is a really good writeup but I can't quickly find it-- the timing at 5k should probably be a little less than what the orignal specs (drop down to 33/34 degrees) say due to piss-poor gas now days. All the info you need is on the bb if you can find it:D
 

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I generally agree with the above posts - to a limit. The normal idle jets for these carbs on a 2L Alfa engine are 50F8. I like to run a little lean and I prefer 50F11. But if he has these jets and he still has the problem and it is alleviated by screwing out the idle jets, then I say he has either an air leak or low float level. I don't agree that putting in bigger idle jets is the solution. It may mask the symptoms but not cure the problem. Say he has an air leak and he makes his engine run better by installing 55F8's. Then the leak gets bigger. What should he then do, install 55F9's?
I agree if he has normal range 2L jets and has to run the idle air screws out 4 turns (or 8 flats) then he has other problems. I believe I would check the jets and the fuel level first. the idle screws out and a huge flat spot reads like the jets are too small--but you never know until you look
 

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Ed, how do you tell how many degrees you're at when the timing marks are M P F?
A page from centerline (I don' think Joe will mind) showing how you engine came timed from the factory. http://www.centerlinealfa.com/tips/images/p51.pdf

Another page with cam timing templates to see what your cam bearing marks are from the factory and how to re-mark them where you want. (102-102?)
http://www.centerlinealfa.com/tips/images/installation/cam_install.pdf

When the cams are set correctly, use a timing light and set the pointer to M on the flywheel or a little under by adjusting the distributor (after loosening) at 4~5k rpm . There are many variations but this will get you in a nice manicured ballpark.

A dial back timing light will read off in degrees from tdc if you need to know exactly how many degrees you are from tdc
 
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