Wade Nelson

Hoses were ok, even so I "freshened" the ends by chopping off 1/4". I put an aftermarket 1-way valve between the tank and the dash. That will help me determine where the problem is. I suspect the 1-way valve at the tank itself is stuck open, or intermittent.

FWIW the easy way to find manifold leaks is to use a smoke machine which pressurizes it to 2-3psi.

Just a caution to noobs, RCB is recommending measuring INTAKE vacuum not MANIFOLD vacuum. Be sure you connect to the right port.

I know I'm eventually going to have to go there. Thanks for the reference. Guys like you who document what you've done seen and found are what make the Internet and forums like this so incredibly valuable. THANK YOU!

Is every previous owner an idiot? My 1980 ZX runs well, accelerates very rapidly, gets nearly 30mpg highway. It would be very hard to complain, performance-wise, for a car with 207,000 miles. Still, I had this nagging suspicion some power was being left on the table. I had a local guy who has owned numerous Z's drive it and he told me the same thing, he felt like it was missing a little power, might need a valve job, compression down a tad perhaps. Today's earlier discussion about octane and pinging, and advancing the timing made me think...why am I NOT getting any pinging under heavy load? NEVER! NONE! Timing incorrectly set? Timing advance mechanism not working properly? So I pop the hood, hook up a piece of long hose to the distributor advance, and suck on it. The plate rotates, begrudgingly. Like it hasn't been getting worked. Clearly it deserves to be taken apart and greased, re-assembled. Even so, it's providing SOME advance. Next I decide I'll inspect the little piece of hose on the other side of the 1-way vacuum valve feeding the advance mechanism. I decide to suck/blow through it, and guess what. The idiot (previous owner, or his mechanic) had installed the valve backwards. I was getting NO vacuum to the distributor mechanism. I'll report later in the day after I've had a chance to drive what sort of difference it made. My guess is it will provide this motor with an additional 10-20 horsepower WHERE IT COUNTS, and at LEAST an additional 3mpgs. Maybe you want to check yours.

Alcohol added to pure gasoline will actually RAISE the octane rating, while lowering the amount of energy delivered per gallon. You WILL get measurably worse mpg's with gasoline containing alcohol. My 4-Runner, which has a knock detector, runs perceptibly better on Premium fuel. My 280ZX, I've never been able to tell any difference in performance. I live at high altitude (6000') and that reduces octane requirements as well.

Your choices now include injecting some fluorescent dye, pretending you're a CSI and putting on the yellow goggles and waving a blacklight around, or filling it up and immediately driving over to a shop with a "sniffer" that know's you're coming and is standing by. Might want to Powerwash everything first so you don't see OLD dye from the LAST guy who worked on it Common leaks include schraeder valves and front seal on the compressor. Pinholes in the condenser from rock chips impacting.

http://jalopnik.com/5336153/1971-datsun-240z-v12-for-9800 Anybody know where this car ended up or who owns it today.

That's the definitive Ljetronic article, right there! thanks for posting!

Here's another website with some good chat about the AAR http://www.hiperformancestore.com/Ljetronic.htm

Annotated... red circle indicates a 4-way fitting. The single yellow stripe was on the BACK of the hose pictured, I couldn't twist it AND hold the camera at the same time... The actuator above the TOP of the picture (not visible) is the "bypass" actuator controlled by the little vacuum switch in the dash, below the ignition switch. Hose is all black. There must be a single white line to the back of the vent (main) motor (not fresh/recirc) but it's not visible in the photo. Hmm, I wonder if it has fallen off...

Here's the money shot...

600 cfm waaay too big even for a 2800 cc motor. It will NEVER run right.

More follow-up. By only filling my tank 3/4 or 5/6 I'm having a lot fewer problems, fumes, vapor locking, etc. I suspect the fuel expansion in hot weather is CONSISTENTLY filling the vapor recovery line with liquid fuel, so then it can't do it's job properly of venting the tank. With fuel leaks fixed, never filling it to 100%, a toggle switch for the auxiliary fan, and alcohol-free fuel, my vapor locking problems have almost completely gone away

More follow-up. By only filling my tank 3/4 or 5/6 I'm having a lot fewer problems, fumes, vapor locking, etc. I suspect the fuel expansion in hot weather is CONSISTENTLY filling the vapor recovery line with liquid fuel, so then it can't do it's job properly of venting the tank. With fuel leaks fixed, never filling it to 100%, a toggle switch for the auxiliary fan, and alcohol-free fuel, my vapor locking problems have almost completely gone away.

YOu've got it backwards, the manual vacuum selector has the most "barbs" or "nipples", the automatic has the fewest. After you remove the console/stereo you can see the vacuum selector on the bottom of the heater/AC control unit. If you'll post some GOOD pictures of your airbox (from all angles) perhaps I'll go pull my dash down and take some pictures of what's connected where and HOW, and together we can put together a "how to" for the next schmoe. I thought the various vacuum motors operating the airbox "doors" were bolted to the firewall, not the airbox itself. Is my memory failing?

Clogged catalytic converters and blown head gaskets go hand in hand. Do a compression check, hot. Nevermind, failed to read your entire post. Have someone hold a rag up to the tailpipe and you can quickly locate exhaust leaks with the added back pressure. Who suggested re-calibrating your AFM? It measures the amount of air blowing past it. Reduce back pressure and more will blow past. No re-cal should (have been) required. Something was wrong to begin with, like running rich or burning oil that caused your cat to clog up. I'd figure what THAT was before doing anything more.

The vacuum lines have stripes on them, white, yellow green, one or two to help you identify them. Vacuum from the underhood storage reservoir goes to the vacuum selector (round thing with 8 hose barbs) "S" for source, hose with red stripe. Yellow/ 2Y goes to the bottom, or "floor" door mechanism. If you get the two lines reversed, I'm not sure it matters, what it gives you is stage 1 and stage 2 of door closure. The green / 2G lines goo to the fresh air intake door above the blower motor. The white and 2 white go to the main vent door on the left hand side of the box. The other vacuum "motor" on the left side of the box gets the plain black hose, which connects to the control switch in the lower dash panel. The "diagram" doesn't EXACTLY show you how all this is done, for instance there was a 3-way fitting on my 2W hose to split it between the vent door, floor door, and dash knob. I'm looking at the "Air flow and Vacuum System" diagram on page Ha-19 of my FSM.

Can anyone give me an idea of the economics of parting out a 280ZX? Worked out good or dumbest thing you ever tried? Saw a '82 2+2 today, smashed on one side, 220K miles, at a car repair shop. It appears to have been sitting for several years. Lots of insect nests. Hood is straight, and I might go for the rear bumper. Alloy wheels look like they'd clean up. Very original, glass t-tops, original dash, etc. What else on these cars will bring any appreciable $? I can't imagine a 220K mile engine or 5 speed is of much interest to anyone. Assuming I could sell the remaining steel to a junkyard for $200, what's it worth? $400? $500? If anything on it is worth $50 or more to you, let me know. It's too far away to tow home, so I'd have to take a trip and strip anything I thought might be e-bayable.

Sounds like an ignition problem to me. Check spark plug gaps.

A good R-134 conversion should provide plenty of cold air. I would suspect you have either air or water contamination in your system. Replace the dryer, pump it down to 10 microns or so, and THEN recharge with the PROPER amount of R134 and I'll bet I never hear you complaining again. Overcharging is worse than undercharging. YOu could start by simply bleeding off some R134 while watching a thermometer stuck in the vent to see if you're overcharged. Let it settle for 3 minutes or so between each bleeding, and put a big floor fan in front of the condensor so you're not just battling an ever hotter engine bay. Think about it this way --- new cars get plenty of cold out of R134, why shouldn't yours? There's no black magic even if the expansion valve is slightly different.

Have you actually tried everything suggested here? Heat it with a torch for 20+ minutes, until the surrounding block is nice and toasty. Get the bolt cherry red if possible. Immediately apply dry ice to the bolt head, have several pounds of it ready. Then vice grips, or a pipe wrench if you can get one on it. After that, find a machinist to weld a nut to it...and do it again! I concur, I'd stay away from the EZ outs. If it's in that tight it's just going to break off the EZ out.

Doesn't rubbing panties together usually generate a lot of smoke and screeching???

The ELECTRICAL switch on the dryer is a low pressure switch to prevent the compressor from engaging if loss of R12 occurs. the brass doo-dad on the dryer is a physical pressure relief switch which will vent R-12 if pressure gets too high. Most newer cars have both a low AND a high pressure electrical switch.

$100 sez the mechanics didn't do anything that wasn't suggested here.