1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

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Old Oct 25, 2001 | 08:28 PM
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Brian P's Avatar
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From: White Rock BC
carb experts

ok, I just rebult the stock nikki carb. Not much too it, very simple design. In the main body there is nothing to screw up. Just unscrew everything, clean it, put it back in. Right?

The float height took me some time to setup, the new needle and seat assy was slightly different I guess cause I had to reset the float level by alot, drop was ok..

The car kindof had the same problem before, it wouldn't run without the choke pulled out. Now it runs without it just really shitty.

I finally adjusted the carb enough for it to run on its own, but it won't idle under 1k rpms and it shakes quite a bit.. almost like its running on 1 rotor. It revs nice but it seems to bog for a second when you floor it quickly.

Compression is 120 psi on all rotor faces, both rotors, plugs are new and they are firing... cap, rotor, points, timing are all fine.

also the idle speed adjust needle doesn't seem to do much, if I screw it all the way in it does nothing. If I turn it out too far the idle gets really rough (3-4 turns) Could this circuit be the prob?
What did I screw up?
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Old Oct 27, 2001 | 10:16 PM
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It sounds like you have a vacuum leak. You didn't say what year your car is but I bet it's an '81-85, and the shutter valve hose has a crack in it. If not that, then one of the bijillion other hoses in the engine bay... time to get out the can of carb cleaner and carefully spritz hoses and connections down to check for vacuum leaks. (you've found the leak when the idle suddenly changes, usually revving up/smoothing out a little)
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Old Oct 29, 2001 | 08:13 AM
  #3  
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From: Trying to convince some clown not to put a Holley 600 on his 12a.
Yeah, PeeJay's nailed it again. The fact that your idle screw does nothing for you indicates it's getting a steady supply of air from somewhere.
As far as steping on it, that sounds like a simple accellerator pump adjustment. The lever edge that is sticking out of the pump housing...(The other side of this part of the lever hits the diaphragm piston-looking-thing...know where I mean?)
...this should be sticking out at the top of the accelerator pump housing just a little bit, so it does'nt run parallel. That's a perfect starting point, and adjustment should be made in about 1/4 turn increments.
Check for a healthy pump shot from the jets at the top of the primaries when you operate it by hand. Should be a good long shot.
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Old Oct 29, 2001 | 10:46 PM
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From: White Rock BC
I didn't think that it would be a vaccum leak, I replaced all the vac lines and cleaned the baseplate really well. I ended up swaping carbs off another car because I was in a hurry. That seems to have fixed it. Meanwhile I'm taking the one that didn't work apart again and its soaking in solvent right now. I'm Going to go through it again and check everything.
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