ApexGoblin Posted April 29, 2012 Share Posted April 29, 2012 (edited) I have lurked on this forum for awhile now, but haven't been able to find a solution to this problem... I have a 3/74 260z and I decided to get the motor in it running, (l28 n/a) I installed a set of weber 32/36 dgv carbs (not new) and got the motor to fire and run. However I cannot seem to get it to idle below the 2.5-3k rpm range, I can get a steady idle at around 3k rpm with the choke slightly on. If I take the choke off entirely the motor climbs to 3k and then slows to around 1k and then starts to "gasp" or shudder and then climbs itself back up to 3k. It repeats this process at a steady pace climbing and falling to rise again. I played with the idle speed and idle fuel mixture screws all day today thinking that this must be the problem, but there was almost no change to the engine response. I did get it to idle at around 1.5k for 30 seconds before it died (this was also achieved using choke manipulation with idle screw adjustment). I'm not really certain what may be causing this issue? Electrical? Vacuum? Everything seems to be hooked up and operational. Am I missing something? Has something electrical gone bad? I need a little help seeing as I am new to L series motors. If there's a thread on here covering this specific problem please direct me to it, I tried to find it but maybe the search function failed me. Otherwise any insight or tips would be really appreciated! Edited April 30, 2012 by ApexGoblin Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted April 29, 2012 Share Posted April 29, 2012 Sounds like vacuum to me, masked with choke. Could also be carb balance, as increased engine speed masks that too. Shouldn't be electrical. May just want to hunt for a used set of SUs and be done with it-they have really dropped in price since most of the super motivated speed guys are going hybrid. Nice ones now are selling for what crappy ones used to sell for. Quote Link to comment Share on other sites More sharing options...
OldAndyAndTheSea Posted April 29, 2012 Share Posted April 29, 2012 (edited) Yeah sounds like vacuum to me too. Check all your vacuum lines for loose connections or cracked hoses, and check the tightness of even your manifold bolts you may have just forgotten to tighten one of them. Ive done that one or twice on my car, thats for sure.. haha. A little air makes a huge difference. The fluctuation leads me to think vacuum. Otherwise I'd say adjust the butterfly's and linkage on your carbs. Cheers and enjoy the car Edited April 29, 2012 by OldAndyAndTheSea Quote Link to comment Share on other sites More sharing options...
jasper Posted April 29, 2012 Share Posted April 29, 2012 Some pics of the installation may help. Quote Link to comment Share on other sites More sharing options...
ApexGoblin Posted April 29, 2012 Author Share Posted April 29, 2012 Hmm ok I'll give it a thorough once over and see if that changes things. Thanks! Quote Link to comment Share on other sites More sharing options...
ApexGoblin Posted April 29, 2012 Author Share Posted April 29, 2012 (edited) Picture of basic install Distributor area Vacuum tank? Haven't touched this besides checking connections/ Cap And the only things not hooked up are one tube from the smog pump, and whatever goes to that gold plenum (I have no idea where that connects but no matter what I connect to it it doesn't seem to change symptoms) Hope this helps, of there are any other specific pictures need please let me know. Thanks for the help! Edited April 29, 2012 by ApexGoblin Quote Link to comment Share on other sites More sharing options...
ApexGoblin Posted April 29, 2012 Author Share Posted April 29, 2012 (edited) Mods can this be moved to the L series specific forum instead of the chassis specific forum? i think i may get more help there. Thanks! Edited April 30, 2012 by ApexGoblin Quote Link to comment Share on other sites More sharing options...
The Crusher Posted April 30, 2012 Share Posted April 30, 2012 I have been running Webber carbs for about 20 years, and they are a good carberators. With that said, Apex, that "gold plenum" hooks up to the air cleaner, not the problem. But I would also say you have a vacumm leak,and I also saw that you are missing a NUT that is supposed to hold down the carb. It is on the front carb in the last picture you posted. That could also be part of your vacumm leak problem. Hope this helps. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.