SU Carbs different and not running good

[neoxman]

I tried 180 deg. turns and it went real lean so it must mean 360 deg. turns. I think i've got it closer but it's very hard to tell what is a good fuel mixture.

[zack_280]

If you are running rich, your exhaust should have some color to it. You can also pull your spark plugs and if they are very sooty, you are probably running rich. If you are running very rich, your car should start easily without any choke while cold. I had all of these symptoms when mine was running rich. I have my idle mixture set at 1 turn (360deg/turn). Originally it was set at 2 turns. Now it is difficult to start without the choke and it is running much better. The exhause smells better. I pulled the plugs and they are pretty clean. Everything is better.

Good luck.

[beandip]

It seems obvious that neoxman is in WAY OVER HIS HEAD. Is there any member that lives close to where he is ?? He needs some help here.

[ezzzzzzz]

Try this. Relax 'cause you're trying too hard. Reset the the carbs to the initial settings, 1 turn on the idle screws and 2.5 turns on the mixture nuts. Start the car and adjust for equal flow and best idle around 750 to 800. When the engine is idling smooth then slowly (1/4 turn at a time) turn IN (lean) one mixture nut until the engine starts to miss or idle rougher. Turn that mixture nut OUT (richer) 1/4 turn from there. Do the same thing to the other carb. Reset for equal flow and idle around 750-800 using the idle screws. That should be close enough as this is only applicable to idle. If it just doesn't want to idle as before then turn the mixture nuts out one more 1/4 turn (you probably won't need to do this though). Turn the linkage screw up at the balance tube IN until the engine is revving at about 2700-3000 rpms (it will be loud). Now, adjust the screw on the linkage between the carbs (it's nearest the rear carb) until the carbs flow equally using the unisyn (you'll have to turn the center section of the unisyn out to allow enough airflow at this rpm). When you've got that sync'd then turn the screw up at the balance bar back out until the engine is idling again and the screw is NOT touching the linkage. The car should turn off easily without run-on. It should start easily when already warmed up. It should require the choke to start cold. You're done. Enjoy driving the car a little.

[sblake01]

I've been watching this thread but have been reluctant to comment since I don't do much with carbs these days but worked with them quite a bit back when I had 240Zs, 510s, etc. You appear to be dealing with an unmatched set of carbs, Mickey Moused together by a previous owner. I doubt that you can ever get them to work properly. That, coupled with evidentally limited experience, led you to replace thing that might not have needed replacing. Rather than continuing to throw parts at the problem, as they say, why not start with a pair of proper carbs as Gary suggested? And get some hands on help. I'm not quite sure where San Mateo is but I don't think it's close to me or I'd volunteer.

[sblake01]

neoxman, view post #6 by zguitar71 in this thread.

http://www.classiczcars.com/forums/showthread.php?p=191094#post191094

[neoxman]

that's pretty good beandip... yeah I may just be in over my head I forgot to mention i checked the needles and they're both N5 needles but the ink was wearing off and i couldn't find these in a list of needles for the z.. including brit. neeedles.

The problem is the car is in really good condition other than these freak carbs and was well maintained prior to sitting for 5 years. Don't get me wrong i think the SU's are an amazingly simple design, it's just the mixed bag i have to work with could be more than a weekend tinkerer can handle.

I just want to get it running smoothly enough until i go much bigger engine-wise and put maybe a rebello motor in it. so that means carb change too. I feel i'm 90% there but might have to go back and check the front float level before re-adjusting idle mixture. Front as i cannot set the rear float level.

I'll try some of those tips you guys gave me to eek out that last 20% out of these carbs.

[zack_280]

Good luck. Sblake may be right. Try the tips you've been given here (and whatever else you want) and if that doesn't work replace the carbs.