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Hi Andrew, I will make it a higher priority to do some shielding around the exhaust pipe under the tunnel. You are right that tunnel gets pretty hot. my compressor is mounted on a huge braket in front of the mech fuel pump which has been removed. Is that where yours is? At what speed/rpm do you feel this vibration? It could be that your ac is overcharged? Can you measure the ac high pressure side while you are feeling the vibration to see if there is a correlation? I just noticed that you are in Austin. I live off Parmer Lane West of RR and come into the Parmer/Mopac area during the week. How do you like this 105 deg weather? don

Thanks for all the ideas. Fortunately, for me I have covered parking where I work. Otherwise I doubt I could drive the car daily in 105 deg heat. Like you all say, sitting outside in the sun creates a horrible heat soak of the interior that's almost impossible to overcome. I've had louvers since 1976. To me my car looks naked without them. Darker windows, I dunno, I don't want to look like I'm a member of the Sopranos or something like that. :pirate: and I like to see out at night too. I'll start with replacing the floor insulation with new sound and thermal insulation and get some up on that firewall as much as I can. Newer cars have heat shields inside the engine bay that shields the firewall. That would take more effort with all the openings for cables etc. I was thinking a heat shield on the exhaust would not help as I'd think that flowing air as I drive along might manage that. That air must not be enough, otherwise the shifter would not get so hot. The rubber boot has been replaced. So I'll try to figure out something there with exhaust pipe tape being another option. I had already fashioned some heat shields for under the carbs and that made a nice difference in reducing vapor locking. So that would say shielding exhaust underneath should be a useful thing. Despite the record heat this year vapor locking seems to be less a problem even after a very long hot soak. I wonder if the gasoline formulation has changed a bit so its less volatile? I have an aftermarket ac setup with a sanden compressor. I had the old 1 lung York for a long time. The Sanden is a lot smoother and takes less hp. However, I think the original 36 year old expansion valve does not work as the low side pressure is very low no matter how much freon I put in there. I'm going to wait to replace that expansion valve as I'm afraid its going to be quite a chore to break loose those fittings that have been intact for 36 years. That will be a job for winter when I don't need the ac since it will probably take a few weekends of effort. regards don

Sounds like you might be a hardware hacker, I am one of those, and not too ashamed to take the cheap route if I learn something in the process. It it were me I'd probably replace the whole board with a circuit that uses a 555 timer used in monostable mode. Then just tweak the R/C values until you get the right readings on the meter. I suspect that you are correct that the tach meter itself is nothing more than a ma meter, maybe 0-1ma and I'm sure you can figure that out pretty quickly with some resistors and a voltage source. However, before you canabalize it totally when you take it appart look for poor connections or any kind of corrosion. have fun don

I'm happy to say that my '73 has become more of a daily driver. Lately with temps in the 100+ I'm thinking of doing things to reduce interior heat. I'd appreciate any comments from others with similar efforts. I thought I'd start with some sound deadning stuff with insulation on top for the floor boards and stuffing insulation between those plastic body side panels and the body exterior. I notice that the gear shift lever gets really hot. Is that just conductive from the tranny and engine or is it from the exhaust pipe and hot air coming up the boot? I thought about wrapping the exhaust pipe and header but that invites rust. On newer cars I see nice heat shields between body and exhaust pipes. Maybe a trip to a junkyard would yield some ideas and parts that could be adapted for the 240. I have an ac that works marginally, needs a new expansion valve and could also benefit from a honda blower. its more fun driving it everyday now. don

What kind of fuses does the 83zx have, the blade type or the barrel glass type. I have an 81zx, its got the barrel glass type so if yours is like that I can post the 81zx stuff. Don

tks Stephen, That pretty much answers my questions. My 240z shows 30 ohms so I suspect its close enough. Now I'll see if I can mod that 280Z gauge to fit my 240z dash. Then I'll have a voltmeter instead of ammeter which no longer works due to my direct routing of alternator to battery instead of thru cabin. Don

tks Bob, I hadn't considered that option. Good thing about those is that they would be more tolerant of petrochemicals too. Don

Just want to mention that after playing around with fan clutches 20+years ago I switched to a spacer and metal flex fan. Doing this practically eliminated all my vapor locking problems that I had. I live in Central Texas and 105F summer days are common. Before I did this after a hot soak the old Z did lots of bucking and snorting despite doing all the vapor locking trick fixes. I've also not had any issues with water pumps either as the whole contraption is lighter. BTW, don't use a fiber glass flex fan. I tried that, it didn't flex enough so it sounded like I was flying an airplane. Don

Hey Six shooter, did you keep the original rear axle when you went to the 5 speed? I've got a very sad 81zx with a 5 speed that I'm thinking robbing for putting into my 73 4 speed. So far everything I've read recommends trading the rear axle at the same time. I'm mainly looking for quieter highway driving and some mpg improvement not to mention the cheap thrill of one more gear to shift. Don

oh, one more question for you, does your 280Z have a voltmeter or ammeter? Have you happened to check the resistance of your sending unit? Don Don

Tks Steve, you've given me confidence to try it. I was conerned that I was missing something. I'll run down the gas tank as far as I can then pull it. There is an old fashioned hardware store near me that has all kinds of O rings so I'm sure that I can find something close. regards Don

Does anyone know if the resistance range on the sending unit on the 240 vs 280 is similar? Reason I'm asking is that I'd like to swap out the combo ammeter/fuel guage on my 240 for the fuel/voltage gauge from a 280z. Hopefully, the resistance range is similar. Reason I'm doing this is that I've routed the ammeter charge wire direct to the battery instead of the thru the ammeter in the car. I had excessive voltage drop coming into and out of the car interior. BTW, I did route it directly thru an inline fuse. It perked up the charge voltage at idle substantially. regards Don

My 73 stock has developed some slight gasoline leakage around the gasket for the fuel level sending unit. I've looked at the arrangement a bit and gotten the wires off. Its not obvious how to remove the sending unit. It looks like a simple twist of that ring will get it loose. This does not seem like a very reliable way of securing something that is holding back a full tank of gas. :paranoid: It looks like if I grab that ring with channel lock pliers it would come loose with about a 180deg rotation. Is that right? Don

OK, I just found this place. http://www.nostalgicairparts.com/air-conditioning/o-ring-expansion-valve-52.php They also have a complete ac kit just for the Zs and their prices are reasonable. Now I just need to make sure that the threads are correct. regards Don

Hey guys, I've got a 73 with the add on ac. The whole thing actually works fairly well but I've figured out that the expansion valve is stuck. Any ideas on where to get a replacement? Thought I'd get the parts and then do this work in the winter. Just got it working again after frying the idler pulley. Sure made driving it unpleasant here in Central Texas for a while so I am looking forward to improving it with the replacement expansion valve. Maybe I can clean the valve and fix it. However I doubt it since this is the original. May be a bugger to get loose. regards Don

I need to figure out how to post a pix cause it looks ridiculous now. I had an old truck exhaust system in my junk pile. It had huge chrome tips. I sawed off the end and it is jammed up into the turbo muffler end and sticks way out about a foot. I'll clamp it lightly so I can remove it. We'll see what happens to the smell now. Don

My wife never was too interested in driving it anyway since "it rides too rough". Now she thinks she would like to have a Miata convertible or the Pontiac whatever. Mid life crisis I guess. Problem is that it will have to be a slipamatic. Unfortunately, what we really NEED is a 3/4 ton turbo diesel long bed puller truck so that will have to be my new sports car I guess. So that's why I gotta keep the Z going for me. Don

Actually I think you could say that if you have a z with perfect hatch and tailight sealing back there, everywhere, then you probably won't have a problem. Problem is that its not possible to make the seal perfect easily so if the tailpipe pushes the exhaust outside the envelope so that it can't be sucked back in then perfect sealing in the hatch area may not be such a strong requirement. I'm pretty sure the whole exhaust system is solid from beginning to end. This one has held up remarkably well. Must be the thickness of the pipe. I wish I'd had that 3M stuff. For that fuel pipe filler gap I just squirted butyl rubber caulk in there all around it. Its sealed off now, but also kinda permanently glued in place too. regards Don

I'll go surf those links, good data I'm sure. My post was long, but from day one windows down was exhausty, windows up never a problem. Maybe I'll just fix the ac and forget about it like I've done for 30+ years. I've always thought a front air dam would be cool but then I think about those parking lot curbs being there and pieces of rubber flying off 18 wheeler recaps like hit my poor old 73 capri front air dam. I'm gonna play with the exhaust tips just for the heck of it. Who knows make it exit out the side or down. I do have a nice non-rattling loover on the rear window. Helps keep the temp down and reduce need to lower windows as cabin temp stays lower with the shade. tks for posts guys Don

I read the previous posts on this and there was someone trying some customized tip lengths and shapes to help solve the exhaust fume problem. I'd like to know what results he got if he's still around here and can post them. I've go a 73 240 I've had since '76. Its always had an exhaust fume issue with the window(s) down. Since here in Texas we usually always have the AC on its really not much an issue. However, lately the ac is on the fritz and besides it sure would be nice to have a breeze and not be smoked out. The exhaust is an old turbo flow 2.5" from Motosport a long time ago. Basically a big muffler on the end. It has held up remarkably well. I should say that I've also had Monza and stock exhausts and they had the same fume problem. I can't find any obvious gasket voids. My most recent effort to fix it involved caulking around the fuel tank downspout on the rear back corner as it comes into and out of the car on the way to the fuel tank. There was quite a bit of light showing thru there. Everthing else from tailights, hatch, hatch gaskets seem to be in good order. Not new but not rotten either. That helped some but I still smell it with the window open. I have never tried the tailpipe extension trick so I'm about ready to try that. At the moment the tip goes about 2" beyond the tiny rear bumper. I've noticed some vehicles with exhausts that come straight out then curve down so that the exhaust tip is perpendicular to the air flow of the vehicle. So I was wondering what if any experience have people had with the curved tailpipe extension and direction change. Curved down or curved to the side. You could make it go either way. And suggestions on max length to start with would be appreciated. I suppose someplace like a generic muffler shop would be the best place to get something bent like this. I know it won't look cool but I'll try to fix that later after I can breathe while I drive.:sleepy: The AC needs a new idler pulley and that is in the works. tks Don

Great, tks Zbane. I do remember that name now that you mention it. Must have been on some catalogs that my wife threw out. I see you have an 81zx. I've got an '81 temporarily sidelined. What's problematic? I notice that somewhere around 225K miles the bearing in the distributor goes bad and timing starts hopping around until it dies. Besides that the fuel pressure regulator is a commonly failing part. The 240 is a lot simpler. again tks for the tip! Don

I was going to finally order those tie rod ends, ball joints, and rack boots, and other rubber suspension parts for my '73 240. I just want to stay oem so I got out my Victoria British catalog but when I look on line it appears that they do not do Zs anymore. Did they sell this part of the business to someone? Is Motorsport now the place to buy suspension parts, rubber bushings etc? Any other recommendations. I don't want a hot rod. These kyb's have softned up the ride quite nicely so I don't want to mess that up. Too many back surgeries. I'm lucky to be able to drive it at all. Sorry if this ancient history. I've been daily driving for a while since I put on those KYBs and now its time to give her some more attention. tks Don

I need to get them off so I can replace the decayed booties over the end of the rack. And the rubber that holds grease around ball joints is shot although the joint itself is actually ok. Main concern is keeping grit dirt etc out of the rack. to be honest I've made that same arugument you made for the last 10 years. But whenever the weather is bad I won't drive it so crap doesn't get in there. tks for the interest Don

tks Nissanman, so the port side is LHT nut. I don't think I can blaim the alignment guys. Mine is still in the factory original setting. Unfortuantely, the ball joints are factory original too. So you don't think that heat will be required? tks Don

I am getting ready to replace tie rod ends and the the rack boot etc. The last time I tried doing this I could never get that lock nut loose. Does it require heat? Long cheater bar? Maybe its reverse thread? btw its a 73 240 tks Don