Multible 94 carb questain

metalman

metalman

Member
Posted this questain on the HAMB, guess the 94 experts were taking the night off over there so guess I'll try here, bet some of you have messed with multible carbs on a flatty before!
I'm running 3 94s on an Offy manifold. Got the motor running great with the center carb and the outside carbs removed and block off plates on.
Put the outside carbs on and the motor runs 3000 RPM with the throttles all closed. Messing with it I tried it with the front carb removed, back carb on and it runs perfect again, idles just fine. I assumed it must be an issue with the front carb so I changed it out for another. Same issue, runs 3000 rpm again. Do I have the same issue with 2 different carbs and if so, what is the problem with them?
FWIW I did switch the carb bodies on the base plates and that told me it's got to be something with the base plate, the front carb body ran fine with the rear carb baseplate. The outer carbs do have the idle circits blocked off and the power valves blocked.
I'm stumped, anyone have any ideas?
 
When a butterfly is open, air is drawn in and the idle increases. Maybe one of the butterflys is installed upside down, and won't close completely. On the 3x2 setup, the idle speed is controled by the center carb. The end carbs butterflys should be shut tightly.
 
They make throttle plates that are specific for end carbs to close off without sticking. Ther obvioulsy is a problem with one throttle base.
 
I'll take a better look at the plates. I did use the carb plates Speedway sells for secondary carbs and they seem to work fine in the one carb but???.
 
On the same theme, what models are your 94's?? Some of the later ones have extra passages that don't match up with early base plates relating to later choke mechanisms and such. Be very thorough in examining the aftermarket base, too. If you mean aftermarket throttle blades alone, seat them and hold carb base up to light to look for leaks around edges.
 
They are the original bases that came with the carb but of course that don't mean that how they came originally. I did change the plates and shafts.
The one carb that was giving problems did have more light showing around the plates then the other 2, none of them fit perfectly tight (no light showing). I spent an hour carefully filling the plates in the bad carb till they fit as tight as the other 2. Put it all back together and the motor runs great, idles good ( I can back off the idle till it dies) so I guess that was all it was. Can't hardly believe the small amount of change I did to the plates make that much differance! I guess the tolerances on the new plates ar'nt that good. Thank all for the help.
 
A couple of the carb experts are traveling to Charlotte for the Eastern so are probably not online (Charlie NY and Kenct). Don't know where Max is. Be patient and they will have some good comments when they get on. John
 
Metalman, thank you very much for the info on solving the problem. I will be running triple carbs and I will definitely file the information. Dennis/Arkansas
metalman said:
They are the original bases that came with the carb but of course that don't mean that how they came originally. I did change the plates and shafts.
The one carb that was giving problems did have more light showing around the plates then the other 2, none of them fit perfectly tight (no light showing). I spent an hour carefully filling the plates in the bad carb till they fit as tight as the other 2. Put it all back together and the motor runs great, idles good ( I can back off the idle till it dies) so I guess that was all it was. Can't hardly believe the small amount of change I did to the plates make that much differance! I guess the tolerances on the new plates ar'nt that good. Thank all for the help.
Click to expand...
 
You must log in or register to reply here.
Back
Top