Mudge Posted December 9, 2002 Share Posted December 9, 2002 Here is something interesting, I am going to assume its maybe vacuum leak related, but here goes. Basically either the car will idle so low it wants to die (especially when coming to a stop), or if just a minor twich of the choke and it goes from ~500RPM idle to nearly 1200-1500 RPM idle. If I give it a small tap on the gas at the light when its idling low, it will hang around the 1500 RPM mark once again, and if/when it drops its usually pretty slow. Power is pretty good on the street, but I am still suspicious of vacuum leak or maybe incorrect jetting. These are dual Weber downdrafts (32/36), and am assuming the jets are unchanged from the donor setup but am not positive. Now, here is further mystery for me, a non carb person and new to Z land (Haynes manual on the way), the air filters have a barbed plastic connector at the bottom, as if a line goes to them for some purpose, wether EGR or what I am not sure, but they are unhooked at the moment so basically letting in a small amount of unfiltered air. I can snap a pic if this helps, but would you assume this is for EGR and should be plugged up? Or is this for something else that I'm not finding in the harness? 73 240Z, P30 engine (verified on block), idle screws are backed out about 2 1/4 turns Quote Link to comment Share on other sites More sharing options...
Mudge Posted December 9, 2002 Author Share Posted December 9, 2002 Richening it up 1/4 turn helped definately, but idle RPM is still not consitent from one stop to the next, and it occasionally wants to die still. I'll check Napa for a color-tune. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted December 9, 2002 Share Posted December 9, 2002 Mudge, I have the same setup on my daily driver. Sounds like the throttle shafts may be worn, which would cause both an air leak and an unpredictable throttle return. Disconnect the linkages and feel for play. Also, pull off the tops of the carbs (5 screws I believe (and you'll have to pull out the pin that holds the linkage to the choke butterflies) and look for crud in the float bowls. If you pull the tops off carefully, you can re-use the gaskets. This will also be a good opportunity to write down all your jet sizes. The primary and secondary fuel jets sit in the bottom of the float bowls, which is exactly where the crud collects, that may be causing some of your problems. The air filter base holes are for the valve cover breather. I have mine connected to one of the carbs, and the other carb, I blocked off the hole. HTH, Tim Quote Link to comment Share on other sites More sharing options...
Mudge Posted December 9, 2002 Author Share Posted December 9, 2002 Thanks Tim! Quote Link to comment Share on other sites More sharing options...
Mudge Posted December 14, 2002 Author Share Posted December 14, 2002 Ordered a couple books to help get me going. Tim, whats your MPG look like? I think I'm getting about 15 MPG right now, makes me miss EFI! Quote Link to comment Share on other sites More sharing options...
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