moritz55

Hi - welcome to the Zcar forum. I'm moving to Beacon, New York (next to Fishkill) next week and hope to be settled by the end of June. Good luck on your NY inspection - I'll have to prep my car for it once I get settled. Hope mine goes smoothly.

Jonnyrock, your driving style is now similar to mine. Well I just completed a 3rd fill-up. Hoped to get more Highway miles - but anyway put on 198miles and it took 9.5 gals => 20.8 mpg. I did only ~110 miles pure highway and the rest city so not much better than 50/50 highway vs city. This would roughly estimate to be 16 mpg city and 24.5 mpg highway. Hopefully this weekend I can get a pure highway estimate.

Many thanks 'nahurry". With my Mallory Unilite Breakerless Distributor my timing at idle is 15-16 degrees BTDC and at 3000 rpm is at ~38 BTDC. I get some pinging with 87 octane when I tried it. Anyway hope I get as good mileage as you when I take my little road trip in a week.

nahurry , that's great! What's your timing set at if you run 87 octane? Can you also advise what percent on average is City vs Highway miles when you achieve 24-26 mpg? Many thanks ,

Well, I filled up for the 2nd time (I use 91 and 92 Octane) and put another 208 miles on my 240z, got 20.6 mpg. Still ran about 50/50 Highway versus City. I pushed it a little more, and hit 100+mph on two occasions and did 5-6 quick starts and accelerations having some fun. Anyway it wasn't too bad. Soon I'll go on a 190 mile road trip with ~20miles city, the rest highway, anxious to see how it goes.

Good point kmgmz - first thing I did was have my wheels rebalanced once the vibration started a month ago. I had installed New BFG g-Force Sports in the 2-1/2months prior and was not happy with the orginal balancing at Discount Tire? Good tires, poor balancing, had them balanced twice and I was still not happy - so I had them done by a local professional with many years of racing experience, cost me $65.00 for 5-tires inculding my spare. This made more of a difference in the front end, no steering wheel vibration or subtle bouncing. Since all the rear end repair work above and now that I have 600miles on my new clutch, I did get my car up to 100mph Memorial Day, on the interstate - and there's no vibration. Pure engine noise and of course road bumps are about all I hear and can feel. It really seems like a different and newer car. Many thanks..

I had a typo in the above post.... 2nd) To address the vibration & clunk, I got looking at my rear end. My differential mount was pretty much shot, the rubber between both sets of plates was torn. Also as I got looking at the front of the differential, it was pointing down and toward the passenger side of the car. Almost 5/6inch is in error .. should be 5/8inch offcenter in the direction of the passenger side of the car.

I'll share my 1973 240z w/5spd story, maybe it will help. I was getting both a "Rattle" when idling in neutral, a "Clunk" when shifting hard and a terrible "Vibration" at 2200 rpm higher. The vibration felt like the car was going to shake apart it wsa so bad. I had several things done systematically to rule our rootcauses. 1st) Thanks to the knowledge and advice from Arne, the Rattle noise when idling in nutral came from a Clutch spring/coil that was loose. I have an Aluminum (Fidanza) flywheel, and after installing a new clutch (Centerforce Dual Friction) and resurfacing the flywheel - this rattling noise vanished. 2nd) To address the vibration & clunk, I got looking at my rear end. My differential mount was pretty much shot, the rubber between both sets of plates was torn. Also as I got looking at the front of the differential, it was pointing down and toward the passenger side of the car. Almost 5/6inch offcenter in the direction of the passenger side of the car. .. I bought New Parts from MSA: Differential Mount (~$65), Urathene Bushings for Both the Mustache Bar and the Transverse Linkages, 4 New CV U-Joints and 2 Drivetrain U-Joints (Napa pn: P391) were ordered. .. During inspection when disassembled, I noticed the Mustache bar was twisted becuase the differential was off-center. Straightened this up and installed the New Urathene bushings. Then installed the Differential Mount and it took 2 attempts becuase I had to remove the twist in the Mustache bar such that the Differential mount screw aligned squarely with the frame bracket - all before tigthening everything up. I also installed the Inner Bushings on the Transverse links. .. Test drove it and the Clunk was gone completely .. most of the vibration (80% or so) was gone up through 3500 rpm. .. Next dropped the Driveshaft and inspected the U-Joints and did replace both. The Rear one was bad, front was good, but replaced them anyway. The CV U-Joints on the car had been replaced 5000 miles ago and were still in perfect shape, smooth and tight when being turned by hand. Rechecked all the bolts again - no signs of anything loose. ... Took the car out and it was super! No Clunks and No Vibrations up through ~4500 rpm, just pure engine noise. In fact plastic vibrations in my center console/heater control panel are now all gone from 1500rpm and up. So ... my conclusion was - the Major Vibrations starting at 2200RPM was primarily due to the Differential being mis-aligned with the plane/centerline of the drive shaft(the angle of mis-alignment was about 4-5degrees using a protractor and straight edge). It's easy to check for this as well by looking at the gap between Mustache bar and the frame uprights on either side - they should be equal. The higher RPM vibration (~3500rpm) came from a worn U-Joint on the rear end of my drive shaft. I'm sure it was damaged as the differential shifted so far off-center. These ussually don't wear - but in my case they were stressed a bit. Anyway - hope this helps some encountering a similar problem.

Here's one for reference point. I just tuned up my 4BL 390cfm Holley after installing a new ignition on my 240z. I also had a new clutch installed last week so my driving has pretty much 50/50 = highway/city and very light on the pedal since I'm breaking in the new clutch. I just topped off the tank after the tune up and got 20.5 MPG ! I'm pleased since so much of my driving was on the low end of the RPM/Torque range below 3000rpm and under 50 MPH. I'm anxious to take it on a small trip and get an better estimate of highway mileage. I'm sure my mileage will deteriorate as I push it more once my clutch is broken in. I included a photo of my engine setup and the specs below. Hope this helps. Specs on my Engine: - 2.4L E88 Head , P30 Block with Oversized Exhaust Valves (~9.5 : 1 CR) - 4BL 390cfm Holley with Arizona Z manifold - MSD 6A (pn 6200) Ignition box - Mallory Promaster Coil - Mallory Unilite Distributor - Magnecor 8.5mm Ignition / Plug wires - NGK's gapped at .058" -.060" (with the MSD 6A, I get great spark)

Maybe this is a help. I've included 2 photos of my wheels for reference. Mine are BFG g-Force 205/60/15's on 7.5" wide rims. Other reference data: - Front Tires : My car is 1" lower than Stock, I have ~1" clearance between Fender & Tire at Top-Dead-Center (TDC). - Rear Tires : my car is 1/2" lower than Stock, You can see a slighly larger clearance gap at TDC. From your photo the Rims are at least 16" and potentially 17". The width of the rims look at least 7.5" or possibly 8" wide. Anyway , maybe you can take my photo and lay it next to yours resizing it so the fenders for both cars look equal. Then you could measure and try to scale them to come up with a closer estimate. Good luck, Mark

Great Dave - thanks. I'll get this laid out and before I tackle this I'll consult with you. Many thanks!

Hi Dave, I found this older thread from a while back and have a question. I am debating on whether to add an MSD 6A CD unit to my current Ignition and Distributor setup. I've got the Mallory Unilite Breakerless Distributor with a Mallory Unilite Promaster Coil & 700 Ballast resistor hooked up such that my Stock Tach on the 240z works fine. I used this installation recommendation from Carl Beck : http://www.zhome.com/ZCMnL/tech/UniLiteWire.jpg and it works terrific. My question and any advice from other experts as well needed is: 1) Would the MSD 6A 6200 series make much difference on overall performance and starting? 2) How would I install the MSD 6A 6200 series given the setup I have so my stock tach will still function properly? Many thanks and I welcome advice,

Well I made one last adjustment to the Carb Mixture valves and I'm pleased now. I ended up backing off on the mixture screws ~1/4 turn each making them Richer (I have a 4bl 390cfm Holley). I then had to increase the RPM up slightly back to the ~900RPM. When the Electronic Fans now turned on and kicked the Alternator ON, the load from the alternator only Dropped the idle to ~830RPM, less than 100RPM drop. I'm please with this setup. Many thanks for the advice!

As "ozconnection" suggests, get a digital timing light with total advance offset capability and an RPM reading. I bought one for ~$90 at Autozone - works exceptionally well - can't remember the brand. It will also enable you to assure your idle is true using the digital RPM reading as my stock RPM gauge was measuring ~100 RPM faster than actual. I've read on prior posts that setting the L24 at 15-17BTC @ 900RPM is a good setting, then setting with the total advance at 32-34BTC @ 3000RPM. My L24 is set at 35-36BTC @ 3000 RPM and runs real well for me. I also keep my 240z idle set at ~900RPM and am happy with it here. Hope this helps and good luck,

The community I live in - Rochester, Minnesota (home of the Mayo Clinic) is largely populated with medical professionals of all fields, so as an engineer here I'm often a bit out of place. It was interesting while I had my two(2), 1973 240z's on the road up until 1month ago (Green & Orange) of which I had to sell the Orange one becuase I'm moving to NY in several months. I'd drive to the gas station or stop at a major shopping plaza and I'd get comments like: "Love all the Chrome - you don't see it today"; 'Had a 240z,260z,280z and sold it when the kids came along - loved the car"; "What are you willing to sell it for?"; "Is this a Jaguar XKE or was Datsun part of Jaguar?" But the most interesting comment I'll get is : "Hey have you seen the other 240z in Rochester, it's just like yours - but Orange (if I'm in my Green one) or vice versus?" When I tell them that's mine as well - they immediately say you're kidding me OR are you interested in selling it - I'd love to own the car?" Anyway with all the BMW's, Porche's, Mercedes, Escalades and large SUVs in town, I get loads of attention. Last week a ~1955 Corvette honked and gave a thumbs up as I drove by the intersection, so the 240z get's remarkable amount of attention from the US muscle car fans. I'm sure they were very rare in Minnesota and given the harsh winters it really made them extinct. My most favorite ackowledgment has been several times while in my Green 240z and cruising on highway 52 or driving down Broadway (the main street) and the local or state police pull up next to me and give a thumbs up. I just acknowledge with a smile & wave, and of course let them pass me! Cheers all and enjoy the nice weather!

Good idea, thanks for the insight. I did readjust the idle yesterday. Since I have a 4Bl Holley carb installed it's pretty easy to do. I made the Carb mixtures for both ~1/8th Turn Richer, and tweaked the idle back up to ~900 RPM. Vacumm stayed pretty close to it's peak, maybe a touch drop , but I think this was due to the RPM slight drop. When the Fan kicked in it seemed to drop a little less as I observed on my digital RPM meter. It may be my imagination, but I'll continue to tweak it to minimize the RPM drops with the alternator load since my car is a 5sp manual and can't do it as convienently as you with the automatic transmission. Many thanks,