Duffman

Leon, when at steady driving (no acceleration), it runs fine. When accelerating, it starts out fine then starts to miss and it makes a chugging sound. Also, hear valves pinging. I did find a problem with my front carb float valve was sticking, bowl not filling, replaced it and idle still good, but acceleration problem still exists. Yes, have heat shield between exhaust and carbs.

UPDATE: Borrowed a set of carbs from a buddy, installed new plugs, fuel filter, distributor cap and rotor, fuel pressure gauge and adjusted timing to 10 degrees BTDC. Balanced carbs and set idle to a very nice 900 rpms (as low as I have had it in years!). Fuel pressure a constant 3.5 psi on mechanical fuel pump. Idles like a champ, not cutting out anymore. However, under load I seem to find the engine "diesels", or chugs, when warmed up. I have pulled on the choke to see if it is running lean and it does not improve. So, have corrected a long-term idle issue with replacement carbs, but still have an on-the-road issue with the car dieseling/chugging/lugging while on the road and accelerating. Definitely worse when car is fully warmed up. I have not done anything major to the car which would have caused this, other than play with the carbs. I don't think it is fuel or carb related because everything is measured correctly and had the same dieseling problem with old carbs. Any thoughts?

Blue, I appreciate your diligence in finding the above information, have always thought I had tach issues that could be fixed by some kind of adjustment. Will try to digest the info and see if there is anything I can do. Not my area of strength by any means!

Tach jumping, not rpms.

Ok, Enrique, that was cold!!

I have had an ongoing problem with my tach bouncing when I shift. It goes up about 1500 to 2000 rpms when I shift. Doesn't seem to bounce while in gear, or at idle. I searched for this topic but didn't see anything. Any thoughts?

Carbs are definitely in need of a rebuild, with the throttle shafts allowing more of a leak than I would like. I have applied one of Blue's ideas and capped the end of the throttle shafts to minimize the leak. I know the floats are set correctly and have adjusted the mixture to make sure it is not too lean. Appreciate the thoughts, Pete!

Thanks, LeonV, will check it out and report back.

Still scratching my head on this one ... wires seem to be fine. I can start the car, with choke, and it idles fine at around 2000 rpms. At running temp, I drop the choke down and the tach drops to zero and the car dies. It will start right back up, but does not maintain idle. Carbs seem to be fine, fuel pressure constant 3 to 3.5 psi. Any other thoughts? Should I look at my coil or distributor more closely? Coil is less than 1 1/2 years old, not used much. Would my symptoms have anything to do with the E12-80 module possibly going bad? This is not an area of expertise for me, as you can tell ...

Koalia, no ballast resistor, as you guessed. Will double check the fusible link by the starter, though a quick review of my wiring did not reflect any visisble problems. Thanks!

Checked the wires between the coil and distributor, no problems there. Checked the connections and tested the continuity, both seemed fine. Noticed some of the spark plug wires had a white corrosive buildup on the distributor ends, as well as the center distibutor to coil wire. Any reason I would have that issue? Replace the wires? Any other thoughts?

Thanks, Blue, I gave it a quick once over before, but will look closer now.

I should say that I have an ongoing issue with a bouncing tach, but nothing like this.

Am working on balancing my SUs and after reinstalling in the car am having electrical issues (I guess). The car starts fine and then just dies. I notice the car idles fine and then the tach drops to zero and the car dies. Have not had this issue before. Have electronic ignition (E12-80) and using a Blaster coil. Seems like something electrical is causing it to die, not the carbs. Any thoughts?

MSA option - http://www.thezstore.com/page/TZS/PROD/40-2860

Randy, my rear sway bar has the hanger pieces mentioned above, so I can mount it like the pics show. I believe that you can mount the rear sway bar both ways, but most people like to install like the photos above as a preferred method, instead of drilling into the floor pan. However, the rear sway bar I got is bigger than my front sway bar, so am waiting on getting a beefier front sway bar to install before I add the rear one.

Hey, Randy, glad you got your problem resolved!!

Randy, have you tried the clear hose technique to see how high your fuel level is in your float bowl and in your nozzles? See Arne's comment #7 in the following SU post: http://www.classiczcars.com/forums/showthread.php?37771-su-adjustment&highlight=float+bowl

Yes, just the same.

Looks like you have the 3 screw carb mixture nuts, which are from the later domed SU carbs. The piece that seems to be stopping your mixture nut can be removed or adjusted so it is not so much in the way. I believe it is just screwed in in the front of the carb.

My 4 screw carbs are in need of some ZTherapy therapy; sizeable vacuum leaks, etc. While I am accumulating funds to make that happen, I picked up a pair of 3 screw carbs locally to have as back up, or to play with, or what have you. I took them apart, cleaned them up (followed the Just DVDs video) and decided to replace my rear carb (biggest vacuum offender!) with the 3 screw alternative. I was stunned how much better the car ran, idle was able to drop down to 700 to 800 rpm (could never get it below 1100), smooth acceleration, etc. Well, being reasonably stupid, I thought I would replace the front 4 screw carb with the 3 screw and make it run better, right? Wrong!! I couldn't get the car to run without having the choke on, front carb doesn't seem to be doing anything when I adjust the air mixture screw all the way in or out and I can't balance the carbs! Very frustrating! I wish I had just left the 4 screw in the front and the 3 screw in the back! When I went back to that configuration, I ran into the same inability to get them balanced and running smoothly without choke. Got to be missing something simple but can't see the forest thru the trees at the moment! Any thoughts?

Have the MSA rear sway bar, looking to install in my 70 240Z with 83 ZX 5 speed and R200 diff, with the Arizona Z mustache bar. Has not had rear sway bar before and I don't have instructions about mounting correctly. Looked through prior posts but didn't see anything about installing with my circumstances. Any written instructions with diagrams out there that someone could send me? Will contact MSA Monday, but figured someone has done this before and knows the best way to do this. Thoughts? Thanks!

I checked, no vibration when in neutral and revving engine to 3000+ with clutch engaged and clutch let out

Will double check, Arne, but don't believe that it vibrates when revving in neutral.

Huh, I am not noticing any pulley wobbling in the engine, and had a complete engine rebuild about 4,000 miles ago. If the engine or tranny are the most likely culprits, am thinking it would be the transmission, as it was installed without rebuilding off an 83 Z and the vibration seems to be coming from the rear. If that is the case, what would cause the vibration from the tranny? Bad gears, etc? What would be the best way of determining tranny issues?