moritz55

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,

Great advice, I'll be relocating to New York in several months. The weather will be warmer, however we'll still see 10F-30F days with clear dry roads for taking the car out. Shall I assume the Redline MT-90 is good for summers as well as the cold? Many thanks,

Thanks Arne, this is great insight. I don't know what gear oil is in the transmission as it was completely rebuilt when I purchased the car. I know in my earlier 240z when I had the 5sp pulled and rebuilt, the actual gear oil used surprised me - I think was a standard SAE 10W-40W. I'll watch to see if the RPM drop is less after it warms up.... as the gear oil warms up. Lord knows in Minnesota, we have cold weather and just had snow last week. This past weekend it was a balmly 40F-45F and dry so I had a chance to cruise in the 240z. Many thanks,

Many thanks Dave for the answers! I did upgrade to the 60amp '82-'83 alternator with builtin regulator along with adding your ZXP conversion plug to replace the 240z regulator function. It's been super and rock solid electrically ever since. It never occurred to me that it was additional load on the engine from the alternator kicking in to support the higher amperage draw from the electric fans. Great news & Thanks !!! I was wondering if for observation #1, if possibly releasing the clutch causes the overall Vacumm level in the engine to change slightly thus causing a slight change in RPM (~200 RPM drop). I did experience on my older 240z when I had a brake booster leak and could actually hear it hiss that when I pressed the brake pedal the vacumm leak caused the engine RPM to drop 200-300RPM when it was Cold; just after starting (Engine is Running Richer). I also did not have installed the Brake Vacumm Checkvalve inline between the Booster and the Engine. Then once the car warmed up fully and I depressed the brake, the engine Increased 200-300 RPM, with the slight change in Vacumm. Thoughts and comments are welcome, and thanks again Dave! Many thanks again ,

Hi, I've had my 1973 240z now for 18months. I've finally got it fixed up the way I like it inside and out. It has a rebuilt L24 , Firenza Aluminum Flywheel, 1982-83 5spd Tranny with New Clutch/Master Cylinder and an R200 Rear-End. Car runs super and solid. My Question for both Observations: Is this normal, if not what could it be? 1) With car idling once warmed up (I keep it at 900 RPM, 17BTC) and the Clutch Depressed to the floor - it idles rock solid. When I Release the Clutch and let it out while the car is in Neutral - the idle drops to ~750-800 RPM. It then creaps back up to 900RPM after 10-20sec is my estimate. It's a noticeable drop however and very slow creap back up to 900RPM. 2) With the car idling once warmed up (at 900 RPM, 17BTC) and then the electric fans kick on, the car drops to ~750-800 RPM. Once the fans turn off the RPM resumes back at ~900RPM. Many thanks for insight...

I have a 1973 240z with a rear height 1/2inch lower than stock level and the front height 1.5inch lower than stock level due to suspension mods. I installed 15" rims and that are 7.5" wide and would suggest not exceeding this 7.5 " width. I mounted BF Goodrich 205/60/15 g-Force Sport tires and they are a good balance for handling and ride. Just be sure to keep them properly inflated since the 240z car is so light (roughly 750-800lbs load per wheel). BFG recommended to me keeping them inflated at 24-25psi COLD pressure. Good luck, Mark

Back to EScalan's Question: - Yes I did run the range for comparison and stopped at 3500 RPM since my neighbors were a bit upset with the loud engine noise. The net was that the stock tach always measured 100-200 RPM higher than actual. I'm sure my error in reading the tach was greater than the true measurement error as I peered into the car from the window. I did drop my idle down as low as i could go ~750 RPM on the digital tach so the engine still ran smooth using my digital timing light tach, and the RPM gauge in the car actually measured around 50-75 higher. At the low idle it waivered a bit but wasn't terribly off by much given it rests Off at 400 RPM. From my perspective I'm not terribly concerned about the exactness of the Stock Tach to true engine RPM, only it's reasonable accuracy. I am a more a spirited driver and do not race competitively. I've never Red lined the car since rebuilding the engine so for me this works fine and keeps my car as close to Stock on the inside as possible. When I added my Mallory Unilte distributor and Promaster Coil/MAL 700 Ballast I used this link to assure my 240z 4wire Tach could be integrated without major calibration/accuracy issues. Hope this helps some: 240z Tach Wire Hookup: http://www.zhome.com/ZCMnL/tech/MalloryDist.htm Many thanks all,

Mine actually reads ~400 RPM above Zero when off. Not sure why, I thought it may be since my tach was originaly in-operable becuase the prior owner cut the Green/White wire that once was connected to the Ballast resistor when he installed a new coil. Anyway I just rewired the harness in the front and got the Original tach to work yesterday. Have been driving adding >100miles in 2 days and I noticed the Tach rests at ~400 RPM. So - to calibrate the Tach I had a Digital Timing Light with Digital Spark Advance. I used it to validate my Tach at various speeds. Here's what I got: Correct Reading Old Tach Reading Off - Zero 400 RPM 1000 RPM 1100 RPM 2000 RPM 2100 - 2200 RPM 3000 RPM 3100 - 3200 RPM I felt that it was good enough since my car actual RPM was ~100-200 RPM lower than what the tach was reading. I bought the Digital Timing light with RPM gauge for assruing my timing was set at the exact RPM. So it came in handy once I git the stock tach to work. Hope this helps and good luck, Mark.

I forgot to mention in my post above. I own a 1973 - 240z ... Thanks...

Good posting .. I have a similar "Rattle" noise and I can't tell if it's from the Engine or Tranny/Clutch. It's been noticeable sometimes louder than other times in warmer/hotter days. I would appreciate any insight or suggestions. The symptons are: 1) When driving and running in 3rd or 4th gear in 2.2 - 2.5k rpm range there is a noticeable rattle or "clanking type" noise. Sounds like metal-to-metal rattling. 2) When idling in Neutral, Clutch Depressed - No Noise. 3) When idling in Neutral, Clutch Released - Same Rattle or "clanking type" noise. Given symptons #2 & #3, I thought it's my be the clutch linkage? Would it be a throughout bearing? Any insight or suggestions is appreciated. Many thank...

Ttiger - many thanks. Today I did the diagnostic work using an Amp/Volt meter. I uncovered several problems and resolved them. 1) The 3 Prong Relay (Photo #000) with Black, Green & Green/Red wires is still plugged in and the car continues to run fine. It's still a mistery?? Any help on identifying this is appreciated! - Unsolved ! 2) The Red Male Bullet wire (Photo #001) is the HOT feeder wire for the Blower/Fan. It pulls from an inline fused Blue Female Bullet wire (Photo #002). It's on the same Circuit as the A/C with a 20amp fuse. This checks out good and matches the schematic I have from Haynes. - Solved ! 3) In Photo #004, the Blue Female Bullet wire that was plugged into the Black Male Bullet wire WAS were the original clock plugged. The clocks been gone, so the prior owner connected these togther! Guess what - it blewout the 10amp Fuse for the Map Light & Dome Light and every time I replaced the 10amp fuse it kept blowing! So.. thanks Ttiger you were correct... the Map light is on the same circuit, so once I disconnected the the former clock wires and replaced the fuse, plugged the Map light into a Red/Blue(+) and Black(-) leads, it and the Dome Light work perfectly. - Solved ! 4) So the 3prong plug in Photo #003 has white, white/blue (not white/black as I thought) & blue wires were to the rear speaker and antenna from the stock radio. My retractable antenna is wired with a 3 postion switch and decoupled from the stock radio circuit. - Solved ! 5) Finally - as I was debugging the Heater Console Lights (Red/Blue wire & Black wire) I noticed it was plugged into the 2prong plug (Green/White wire & Red wire) on the Fan/Blower/AC harness? As I was inspecting the harness - I noticed another 2prong mating plug with Red/Blue & Black wires matching the Heater Console lights! You guessed it, after plugging the Heater Console Lights into this matching 2prong socket with Red/Blue & Black matching wires, the Heater Console lights are now on the Dash Dimmer and go On & Off when the Lights are turned On & Off. As I now recall - my Heater Console Lights were on all the time when the car was running! So a Happy Accident - Solved ! Anyway, made a lot of progress today and di get my car ready for the New MSA fuse box and Stereo! Many thanks again Ttiger ...

Here ar the photos for post #2 above. Many thanks...

This is the 2nd part of my post above... on wires behind the clock. My clock is removed and has a Vacumm gauge installed, so I know the light is the former clock light. The photos are in Post #3. I had problems again posting the photos...tx 5) Behind the Clock there is a Light, and 3 bullet connectors(Photo #004). 1st bullet has a Black Male bullet wire plugged into a Blue Female wire connector. 2nd bullet has a Black Male bullet wire plugged into a Red/Blue Female wire bullet connector. 3rd bullet is a Female Red/Blue bullet wire that was connected to the Map Light male Red wire(photo #005). Since my Map light never worked - I assume this is incorrect. What would the correct wiring look like? What should the Red Male bullet Map Light connect to? Any help here is appreciated

I'm reparing my Heater Center Console Panel, adding a New Fuse Box from MSA and installing a New Stereo on my 1973 240z. The prior owner messed it up pretty bad when installing the Stereo 12years back, so I decided to do some major repairs and restoration. Removal of the Heater Control Panel was easy! Thanks to a prior thread read post #5 by EScanlon: http://www.classiczcars.com/forums/showthread.php?t=4429&highlight=Center+Control+panel Once I started looking at the wires I noticed many issues and questions as I expected. I can use some help identifying several wires, connectors and recommended fixes of diagnostic approaches. 1) There is a 3prong relay (photo #000) on the driver that was unplugged. I plugged it in and the car runs fine. What is this and should it be plugged in? 2) There is a Red wire with Male bullet connector from the Fan/Blower harness (photo #001) that I believe was connected to a Blue Female bullet connector on the passenger side (photo #002). Is this correct? 3) There is a spare Blue wire Female bullet connector in the Fan/Blower harness (photo #2). What is this is for? Possibly an AC option? 4) There is a 3 Prong Female connector (Photo #003) with White/Black, White and Blue wires and is connected to the Fan Blower harness. What is this for? Possibly an AC Option? I have additional questions so see the #2 post below. I could not post more that 4 photos. Any help is very much appreciated.