DownByTheRiver Posted April 28, 2014 Share Posted April 28, 2014 I have a 77 280z with a Holley 390 on an Arizona Z car manifold. I'm chasing down an issue with a stumble during light throttle. I know very little about carbs, but this is what I see: It appears as though moving the throttle doesn't move the cam/pump arm right away. I've adjusted the pump linkage to .015 at WOT, and moved the orange cam to the #1 position, which should bring the accelerator pump in sooner. I've also went up to a #31 nozzle, which eliminated the full throttle stumble. Floats are set correctly and the car idles at 800 rpm. Idle timing is a few degrees advanced from the factory setting. I have noticed, however, that when the engine is cold, if I move the throttle lever, it moves the cam/pump arm right away, but it'll click after a certain point, and then goes back to not moving the cam/pump arm right away. Is this something with the choke? I made sure the throttle cable is tight from the pedal. When I'm driving using light throttle, I have to let the car build up to about 2500rpm, and then I can go heavier on the throttle/punch it and have no issues. This will all be moot soon as I just picked up an LS, but I'd like to enjoy the car this summer. Quote Link to comment Share on other sites More sharing options...
zacward Posted November 2, 2014 Share Posted November 2, 2014 Buy an Edelbrock 500 and jet kit. Problem solved. That holley is a pos, fuel slosh is always an issue. Quote Link to comment Share on other sites More sharing options...
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