katastrophiik Posted July 15, 2011 Share Posted July 15, 2011 I have a 1977 280z 2+2 that was EFI i switchted over to triple weber carbs 40mm. I installed a low psi fuel pump a regulator and gauge. Now im a bit confused on how to set the carbs on first start it ran a bit but you keep having to pump the gas and it shoots flames out the carbs and dies. Quote Link to comment Share on other sites More sharing options...
Ducer Posted July 15, 2011 Share Posted July 15, 2011 (edited) I have a 1977 280z 2+2 that was EFI i switchted over to triple weber carbs 40mm. I installed a low psi fuel pump a regulator and gauge. Now im a bit confused on how to set the carbs on first start it ran a bit but you keep having to pump the gas and it shoots flames out the carbs and dies. I believe timing is off and or ignition spark is jumping and sparking at the wrong time. I am having the same issue with back fire on my car. It started a few times, idles great. I turn it off adjusted a few things and Pooof, air puff out and back fire. Very strange. My timing is on, probably carb needs tune. Or spark is firing when intake valves still open. So I say check your timing and if the valves and any vacuum issues. I have a friend that will help me this weekend, when I find out what is wrong, i'll let you know. I've been messing with it for a few days now, but I am an EFI guy more than a carb guy. Edited July 15, 2011 by Ducer Quote Link to comment Share on other sites More sharing options...
Lazeum Posted July 15, 2011 Share Posted July 15, 2011 Besides firing order and ignition, the reason could also be flooded plugs. It happened on mine right when I got the car. Everybody wanted to hear the triple and the exhaust tone so the car was started many times with chokes on without having the chance to run the car for good. It fooled plugs and I had the same symptoms as the ones you described Quote Link to comment Share on other sites More sharing options...
katastrophiik Posted July 15, 2011 Author Share Posted July 15, 2011 I turned the dizzy counter clock wise and it stopped backfiring now i just cant seem to keep her running, what psi fuel should i start at and i have NO clue what settings to touch on the carbs at all. Quote Link to comment Share on other sites More sharing options...
neotech84 Posted July 15, 2011 Share Posted July 15, 2011 I would start in the FAQ's there is a thread about triples that has good info. Then the search function is 2nd on the list. Hope you figure it out! Welcome to HBZ Quote Link to comment Share on other sites More sharing options...
Leon Posted July 15, 2011 Share Posted July 15, 2011 What I don't understand is why slap on carbs (or anything) on your car and not have any idea as to how they work? Your next step should be researching online, or better yet, buy a Weber book. Quote Link to comment Share on other sites More sharing options...
sweetleaf Posted July 15, 2011 Share Posted July 15, 2011 What did you set the timing at? Quote Link to comment Share on other sites More sharing options...
beermanpete Posted July 16, 2011 Share Posted July 16, 2011 Your symptom suggests a lean mixture. You might have a vacuum leak. Do you hear any hissing or whistling sounds? Check for unhooked hoses, open vacuum ports, missing or bad PCV valve, bad master-vac, etc. If you have a fuel return line from the fuel rail back to the tank it might not have a suitable restrictor and too much fuel is returning to the tank. Check the fuel pressure at the carb inlet. What is the history of the carbs? If they are used and dirty the idle circuit might be blocked by dirt, gum, varnish, etc. The carbs might need repair or calibration (jetting). Quote Link to comment Share on other sites More sharing options...
katastrophiik Posted July 16, 2011 Author Share Posted July 16, 2011 My fuel injectors were clogged up and rusted up so instead of buying new injectors i found a set of triple 40mm carbs for a steal. and i decided to install them they look 100 times better and cleaner and peoples reactions are priceless when they see 3 carbs. anyways i noticed gas was lekaing on my headers and creating smoke, so i pulled the carbs off and put them standing up and a good amount of fuel pissed out. im guessing they need to be rebuild? Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 16, 2011 Share Posted July 16, 2011 "i pulled the carbs off and put them standing up and a good amount of fuel pissed out. im guessing they need to be rebuild? " Uh... did you drain the float bowls before 'standing them up'? That fuel micturation sounds like float bowl drainage to me. I'm leaning towards Leon's opinion on this whole issue about this point in time... Quote Link to comment Share on other sites More sharing options...
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