Zedyone_kenobi

That looks stunning buddy! GREAT Work.

That will be interesting to watch. That car needs so much work, it will be cool to see how historical significance plays out versus parts car condition...

Everybody breath and take a break. I am going to install new intake gaskets next and report back in a week or two.

HAHA...I will pass on the flat tops, but hell, they may work better! Correct just aluminum... I have not held it there for a super long time, not sure. I seem to remember doing that test in 1st gear, and the problem went away if I held it steady, but I will have to double check.

EDIT: Captain, I will see what I can find out with a vacuum gage hooked up while running! I am going to have gages wire tied all over the place. The source of this is very tricky and nefarious. But I will find it! NO way this is going to beat me..

Okay, Captain, you first... I run a factory air cleaner with the valve cover and fuel bowl vent tubes connected to it normally. It is just so much easier to tune the SU's as much as I have with the air cleaner off. Normally all is hooked up as the factory intended. The car acts the same either way. I pulled a piston out and the amount of shank I have showing in my first carb is appropriate. It appears level with the bottom most surface of the piston, with a sliver of shoulder showing...Not the Venturi groove. The picture in the FSM provided above shows using a straight edge over the bottom of the piston, but it is hard to make out if the straight edge is over the bottom of the piston or over the bottom of the groove. I think whether it is flush with the groove or flush with the bottom of the piston could be made up for with a turn or two of the mixture knob, as beer man pete suggests. I think the jet extension might be a red herring. I have contacted Z therapy about this. I sent Bruce a long PM last week, but have not heard back from him. I was hoping he would find this thread! I think I really need to start thinking about pulling off the intake and put a new gasket in. I MUST eliminate the 'smart' vacuum leak as a possibility or we will never make any progress. I am going to order two intake kits. One for this trouble shooting and ONE for the mikunis or webers that I am going to replace these with!!!!!!

Well the thing is that no stock 240Z should not be getting enough fuel with SM needles installed. (Unless they are installed wrong,which by all accounts they should not be) I checked my fuel bowl level using the clear fuel tubing trick, and the fuel level is coming up to the right height as measured from the fuel bowl sealing surface on both carbs... I am interested in what Blue was saying about scooting the needles up a bit. The unmachined portion of my needles, if you look in the picture above this post, where the letters KD and SM are stamped sticks out quite a bit from the bottom of my piston. I used the trick in the SU video to install them , but maybe they need to be up more into the bore. That would make me run lean. But before I do any of that, I am going to do a few things. First, since the valve cover is already off, I am going to check the valve clearance against the cold valve specs... Second, I am going to install a new valve cover Third, I am going to get the car running and spray around all the intake gaskets to see if there is a leak fourth, I am going to richen up the mixture either by the nut, or by sinking the needles into my pistons more... Did my timing chain look lose to anybody ?

NO sir. Completely smog free

It seems I am at a point where I need to drink a beer and just take a breath today. Steve, I did just what you guys are saying, with cranking down the A/F until I had an idle around 11.0, but it still went lean then started popping. What would be great to know is manifold vacuum during engine run. I have a vacuum gage and I can hook it up with a long tube to my old Vac Advance port which is currently plugged, and see what happens to my manifold vacuum under part throttle and WOT. It is one piece of the puzzle we do not have. All I know is my vacuum is about 20 at idle.

Another piece of the puzzle maybe... The shiny link on the timing chain is by the number 3 on the cam sprocket. Which may mean the chain was already advanced as far as it can be to make up for slop. The thing is the chain still feels a bit lose. I will post a video of the chain on the car... http://www.flickr.com/photos/sdamico/6709111751/

Took the valve cover off and had a look around. Set it to TDC and peeked through the cam sprocket hole first. I took some pictures of it, but they did not come out. But the timing mark on the cam plate, is within the notch on the cam sprocket, and even though the number of which hole the cam dowel goes through is covered up, It looks like a number one is on top at TDC. But I can take more pics to verify. WHat I was wondering about, is I want to verify this is a stock cam. I have no reason to think otherwise, but it is marked E30 and has an orange painted section.. by the way, all lobes are smooth to the touch and show no signs of scratches or wear.

I will have to show you a picture of it. :stupid: OKAY: UPDATE with the wideband! Got the car warmed up. Verified pistons drop uniformly before I went out. CHECK. Checked timing, still at about 16-17 deg BTDC depending on where I position my head...but rock steady. Car started up and was running VERY smoothly this morning.. and as usual, had Zero issues driving around normally loafing around. I make some notes to myself mentally, as it is too hard to drive and write: 2nd gear pull - part throttle, tried this at 20% to 80% part throttle, same results as near as I could remember them... 2000 rpm----13.9 3000 rpm----14.5 4000 rpm----15.8 Popping started 5000 rpm----16-18 Popping too strong to continue at part throttle... I did this repeatedly with the same results So, next I kept the car in second and slowed down to 2000 rpm and went to WOT: 2nd gear pull - WOT throttle 2000 rpm----13.9 3000 rpm----13.8 4000 rpm----13.9 5000 rpm----14.0 6000 rpm----14.2 Well this seems to confirm what we already knew but now we have data...Just to reinforce this I tried another test. I put the car in 3rd gear, and did some 40-60 mph runs using various amounts of throttle input Every time I could get the rpm to rise under part throttle I had an accompanying leaning out trend until it started popping The same run under WOT, kept the A/F right at 13.8 to 14.2 My A/F at idle is 13.0ish So the same problems as before but with data now. :disappoin: Blue, do you still think slop in the timing set would manifest itself in this manner, where it would only be evident at part throttle. I do not see how my throttle position would effect timing, as that should just be rpm related. I am going to pull off the valve cover today and have a look see. I am also going to start seriously thinking about doing an SU swap out now as no amount of 'tuning' will fix this. I will also have at try Bonzi's suggestion.

No, not yet Bonzi. But it is on the white board in my garage under 'things I have not tried yet'. I write all this stuff down, and I try things when I can fit them into my schedule...Today I am off! Yeah federal holiday! So I will do many things today before it rains.

Well I made a movie showing my disassembly of the carbs, cleaning them, performing the drop test, reassembling them, doing the clear fuel line trick to get your float levels right, and starting the car. BUT it is 53 MB large and I cannot find a way to post it on the net. Everything tells me it is too big.

You could very well be spot on. I am going to pull off the valve cover Monday if it is raining and have a look around. I will also do the measurements you described earlier

Correct captain, I only get an imbalance when the damper valve installed. When it is removed, they THWAK together... It is such a fine adjustment that it seems crazy. They should not be that marginal. I and would wager that most of them are not. OR else nobody would ever get them to run right. Today I am going to reverify a lot of things and go for a drive with the wide band hooked up. Update today

That is a great idea Steve! Thanks!

did some digging, this is a 66 Duetto.... Pure pornagraphy. And my love affair with Alfas, continues...

I want to say alfa, but I am not sure... Can any of you guys help me out. That has to be one of the most beautiful roadsters I have ever seen.

Thanks for trying to help me avoid a rookie mistake though...

yessiree That is a fun 'personality' trait with SU's.

LeonV Make no mistake, I am going to buy a set of triples THIS YEAR. I dearly love playing with carbs, maybe I am a masochistic. I have always wanted a set, and after hearing Steve91tt's MIkunis, I am going to pick up a set of triples for DARN Sure. However, I still I need to fix this issue for two reasons. One, if I am to ever sell these SU's, I will want to ensure the buyer that they are perfect. And Two, before I go slapping triples on anything, I want to be sure the engine is healthy and ready to accept them. I found out the compression is spot on already, so that is good. I will get this problem nailed down soon. I would stake my OEM voltage regulator on it.

Captain, I have about 90% success in getting my pistons to drop reliably and steady. My procedure is as follows... 1) clean the parts religiously, meaning I clean the dome, piston, tube, check valve etc 2) Install them together on the carb dry. I ensure that both pistons rise and fall without any sticking at all and make that lovely 'THWAMP' when they hit down as close to the same time 3) I lift up the piston so the filler tube is level with the dome top as it makes it easier to fill. I drop oil into the tube...I have to do this as if I get any oil at all in between the piston tube and dome bore, the fall rates vary drastically, if I keep them clean they are identical. 4) Here is where it gets tricky. I screw in the little brass check valves into the top of the domes slowly. I then wait until the air bubbles have a chance to move out of the way and begin the drop testing. THIS is where my fall rates start giving me issues. THIS is when I get some minor sticking that I have to just play with to get rid of. I have taken both check valves apart and cleaned them religiously. I have measured them and they are identical as close as I can measure them with my micrometer. This last time, I knew that I had it a bit sticking on the back carb where it would fall 90% of the way down and then stop and then s-l-o-w-l-y go the rest of the way. This is no doubt causing my sloppy idle issue this time and I am not worried about it. MY SU experience now totally covers this. THe wideband just made the diagnosis that much easier. I already love it.....!! Just to recap, the piston sticking thing is not new, it is just taking more and more work when I get to step 4 above to get them to fall in perfect sync. Maybe I need to send my carbs back to Bruce and the Z therapy guys for some fine tuning. Just to make sure needle is not hitting the jet (I am rather sure it is not), but I will do the work without a needle installed, and that will allow me to see if it is the needle dragging or the check valve causing me grief. Since I can get it to fall perfectly without the check valves installed, I do not think I have any needle rubbing issues. I would think I could also use a black sharpy and color the jet black. Then do a test and see if any of the black rubs off. Alcohol will take off any extra marker residue. Steve, copy that on the stumble/lean condition, I am ready for that. When data and science come together, only good things can happen.

I am sorry Captain. I was in family time mode last night. I got all the parts safely tucked under the car, and the center console is in but not screwed together. I should have it on the road by Saturday. Monday will be a long data gathering day as I have off work and hopefully it will not rain. I will say this, at idle with the engine almost warmed up I was reading 15.1:1 at about 600 rpm. Then I blipped the throttle and it immediately started to stumble at about 450 rpm and wanted to die, but kept itself alive, but the A/F went to 19.7:1. I bet you a million dollars one of my pistons did not drop all the way down and I was starving it. They have been sticking more and more the more I take them apart and mess with them. Not sure why, as I have been careful and marked them F and B on all parts. But the carbs seem to be fighting me right now. They are getting tired of coming apart and going together so many times. But this little gage is awesome. Install was a snap, worked the first time. Just a lot of soldering to ensure good connections and a lot of heat shrink because I am anal. Again, I will try to get it completely together tonight, and on the road Saturday. But for SURE monday

UPDATE: My innovative wideband O2 sensor came to life today after work. I have it hidden in my glovebox. And it seems to come to life and read very quickly. I have not put my center console back together yet, but I will this weekend, and then I can take it for a drive. Updates to follow.