BTF/PTM

I'm curious about taking on the lighting harness upgrade, posted here: http://www.zhome.com/ZCMnL/HeadlightRelays/JudkinsRelay.htm I'm just researching for now, but it really seems like with the component prices shown on that site, the $150 price tag of MSA's ready-made harness is high to say the least. I'm no expert with wiring, but I can follow a diagram and use a multimeter and have made cables n stuff before. So my question is, on the diagram on that site, is there a need to open the headlight switch to rewire those contacts (to improve 100% of the wiring) with new wire, or can they just be cut close to the switch and spliced that way? A lighting upgrade is appealing, I'm sure most of us can vouch that the stock lighting after the decades is pretty much just there for decoration. Thanks, everyone.

Stupid question - what does "SM" stand for?

Thanks, everyone, once again the group's input really helped a lot. If I understand correctly, the reason a larger master cylinder is sometimes needed is as follows: Despite the cumulative piston travel remaining very small, there is still a larger volume of fluid spread over the increased (compared to stock) total area of wheel pistons, and thus the same larger volume of fluid must be displaced by the master cylinder to achieve the same pressure and piston motion, and thus the small piston has to travel farther to make up the difference. A larger piston displaces the same volume with less travel as it has a larger area. V = PI*r^2*h, with h being the key variable in this case. So basically, it's master cylinder travel, and thus brake pedal travel, that's key to the concept rather than braking pressure. As for the ratio, is there a link to some sort of equation or estimator or anything else that shows how this relationship works? Is it just a trial and error, personal preference thing?

I opted not to put this in the brake system forum since it's not a specific z car technical question. It's certainly applicable to a z car as much as any car, though. Here goes. I do not understand the popular opinion that installing oversize brake calipers and/or replacing drums with calipers benefits from a larger master cylinder bore. A larger master cylinder bore decreases hydraulic line pressure throughout the braking system for a given force at the pedal, this I fully understand. One argument is the moving of a "larger volume of fluid" with the larger bore. What does this have to do with anything? Basic analysis of any hydraulic brake system tells me that, if any one component is for some reason moving farther (such as a piston retracting farther from a rotor) simply becuz it's larger then something is wrong. The larger fluid volume in the system due to the larger calipers and/or pistons and/or added calipers in the rear seems completely independent of actually needing to move that volume any farther than before to operate the components. Is my thinking correct? The one thing that may make sense would be taking advantage of the decreased piston pressure to prevent the wheels from locking due to a now excessive amount of braking force when things are over sized. If I'm missing some key detail, please correct me. I just don't see a relationship between a larger master cylinder bore and better braking as it relates to increasing size and/or number of caliper pistons. Thanks, everyone.

So here's the search function hard at work, I found a very old thread that answered part of my question, but not all of it. So, I figured I'd add to it despite it happily collecting a pension at this point. I'm researching EFI setups. It's already been established that the webbing serves as a heat shield if I understand correctly. My second question is, for a naturally aspirated L28, is there any reason the squished & tapered intake shape like this one linked below: would breathe any differently from the fatter, more rounded ones that I've also seen? An example is below. Is either one preferrable for tuning? Thanks, everyone.

I don't know if the 260z window mechanisms are the same as in the 240z, but you can get at the lock and striker mechanisms very easily once you pull the glass. You may see something like mentioned above, just a chunk of something lodged in the linkage or other minor thing. With the glass out you can remove the lock cylinder, too. The linkage is held to the door cylinder with a tiny cotter pin, pull it and you can test the linkage. DO NOT DROP THE PIN inside the door, it will certainly fall into the farthest, deepest seam in the metal parts. Go ahead, ask me how I learned that one

This turned out to be a very informative thread I'll add on a part b of the question since it does seem to be in agreement that "burning the carbon out" works. For those who made the comments that a few minutes isn't enough, how long is enough, and would a highway blast require that the engine be jumped between lower gears than top (third in our case, I guess) to keep the rpm up? Also seems like the method Jmortensen mentioned would be safer, finding a parking lot or something and bomb around in it. By safer I mean mostly avoiding tickets.

I've actually used the water method, but I did it on a fuel injected Honda and the water was sucked in through a very small tube connected to one of the manifold vacuum nipples. It did in fact blast a ton of carbon out of the tailpipe for a while, but admittedly I have no idea if if was the steam removing carbon from the internals, or just the severly vibrating engine straining with all its might to maintain 4,000rpm at WOT as it slowly drank a couple gallons of water breaking carbon chips off various pieces of the exhaust pipe itself. I got the advice from a friend who builds and maintains his own race cars, so I trusted the source. It was an experience, and I can definitely vouch that a small and steady feed of water will produce carbon from somewhere I've also heard of the ATF method, supposedly it's an incredibly detergent fluid. But, as Jmortensen mentioned, it also creates ginormous clouds of white smoke. Haven't tried that one or Seafoam. Jmortensen, do you have any theory as to specifically what happens to the engine after it's run hard for a while? Is it a thermal efficiency thing, maybe the engine straining brings the air/fuel ratio or work/heat ratio into better balance?

This is pure curiosity, I'm just wondering if there's any real science behind the cliche' of running a car hard to "burn the carbon out" and somehow remove deposits that may be there from loping it along or having it sit for a long time. I know it's an age-old saying, and I wonder if it has (or ever had) validity. Sorta the same as oil change and engine break-in science being largely old cliche's and hearsay. Thanks

Is there even 4" of clearance to be removed from under the lowest point of a z belly? You'd be dragging frame rails over speed bumps. Here's my recommendation: 1) remove springs and internal shock absorbers from inside strut housings. 2) reassemble suspension without shock absorbers or springs. 3) use some jacking method to lower the car the desired 4" and support it statically. 4) weld all suspension joints together so it's a static truss instead of a dynamic suspension. Use lengths of steel rod as spacers between struts and strut towers to maintain distance normally occupied by the springs. 5) drive your new hardtail 240z and marvel at the awesomeness of pure form with state of the art 19th century technology. Just make sure to wear your mouthguard and Leatt brace as NVH (Noise, Vibration & Harshness) may be a bit overwhelming.

I got a straight rear bumper, including the bolt-on standoff things and mounting brackets, that needs to be rechromed for $60. I paid $100 for the front in better condition, it's straight and has good chrome on it and just needs to have a couple dings flattened. It also included brackets.

Stupid question, on topic; what happens if the diff or transmission are overfilled? Are we just talking about leaking past sealing lips that become submerged in fluid instead of holding back splashes, or are we talking something more severe like synchronizers that don't work properly because they're slogging through too much oil? Just curious.

earlycanz, the exhaust manifold gasket is downstream of the cylinder valves, so it is not necessarily indicative of low cylinder compression. Any time an exhaust valve opens and the corresponding piston shoves the exhaust charge out through the valve and into the manifold tube, you'll hear that tick of the leaking manifold seal as some of the exhaust gas escapes from between the manifold and cylinder head. Whether or not the exhaust valves are fully seated when closed (if they're not they'll leak compression pressure) is a different issue. A cylinder compression check and more importantly a cylinder leak-down test will tell you if the head gasket and valves seats are sealing correctly.

I figured I'd update the thread in case this information comes in handy to someone later. I have my uni-syn now, but a couple days ago I was adjusting the idle screws without it in the hope of at least getting a response out of the front three cylinders. Long story short, I discovered two things: 1) something is wrong with the front carburetor other than being out of adjustment, the slide sticks closed when I blip the throttle (the back one responds nicely) and also hangs up going back down. 2) I had to turn the front idle screw in almost two full turns just to get the engine to idle on all six cylinders, at that point I was finally able to pull any one of the six spark plug wires and get the same (and this time much more mild since were six bangs instead of three) stumble when a cylinder stopped firing. Obviously this makes things horrifically out of tune, I was just trying to get all six cylinders firing. So basically, the engine idling on three cylinders isn't the only problem, I've got bigger things to figure out. I'm also armed with the ZTherapy "Just SU's" DVD, so I'll be educating myself and learning to tune properly and also taking apart my second set of 4-screw carbs to hopefully have a good working pair.

Thanks to both of you

Geico is my insurance provider, and the z has the basic liability coverage to make it street legal, but they told me that a collector car insurance provider of sorts would be better for theft & damages coverage since the raw value of a z isnt' going to offer much if the car is stolen or damaged or whatever else. What coverage do yall have?

Motorman7 helped me understand this idea, I think I get the concept. He helped me sync the two carbs, and when I got home I moved one idle screw in a tad since the engine was stumbling so bad I had to blip the throttle sitting at stop lights on the way home. I reset that back carb's idle screw to where the front one is set (didn't change the front one from our initial tuning) so I'll make sure to adjust both idle screws when I run it tomorrow. As for the part that doesn't make sense, I'm confused as to how one carb can dominate the other since each carb receives its own fuel feed. How does having a quarter turn worth of additional idle air flow through one carb end up cutting off air/fuel mixture through the other carb so completely that there's zero power produced by those cylinders? Sorry, I guess this is a question for the carburetor systems forum. Thanks for the quick help on this, guys, I guess it wasn't such a heavy mystery after all

Kudos to anyone who knows where "heavy mystery time" comes from. so I discovered this neat little gremlin today while trying to find a carburetor leak after getting the fuel tank reinstalled. This is WAY more interesting than a carburetor leak. With the engine idling and warmed up, I can pull any or all of the FRONT three spark plugs and there is zero difference in the way the engine idles. Not so much as a hiccup. If I pull any one of the BACK three spark plugs the engine begins to stutter and heave like it should cuz it's running on one less cylinder. The idle, at least to me, seems smooth and easy. No smoke, no stutter, nothing that I could see. Valves are adjusted to spec. Battery and charging system are less than two months old. Ignition points are clean (they look new) and gapped at about 0.018". Cap and rotor are healthy, spark plugs are 200 miles old and gapped at about 0.035". Spark plug wires are brand new, I put in my set of Taylor 8mm's I've been hanging onto just to see if it made a difference. It didn't. Engine has decent compression, it's an L28/N42, even with the throttle fully closed (forgot to pin it open during the test) the compression from 1-6 is 160, 155, 140, 155, 155, 155. I have spark at all six plugs, I used the screwdriver trick to ground each wire to the valve cover to check for spark. Really freaking strange. It does not feel at all like it's running on three cylinders while it's driving, it has plenty of power and is very smooth. Throttle response immediately off idle is sputtery and rough for a second or so, and then it seems to pick up and run just fine. Choke is fully open (whatever "deactivated" is called) during all this. Any ideas? I worked with Motorman7 over the phone on this for quite a while, and my dad as well who's got 40+ years of gear head experience. This one's got us all stumped.

MikeB, did you flatten the straps for ease of clean-up and prep? I left the bends in mine, didn't think much of it.

Glad I can help, this forum has helped me tremendously as I've fixed various bugs on my z so I'm happy to return the favor. If you see brake fluid anywhere on any part of the wheel hub/brake cylinder assembly, you have a leaking wheel cylinder and/or a loose bleed nipple or brake line fitting. Check all the fittings first, I found a couple that were just loose enough to ooze when I did my brakes recently. Cinch them down with the proper flare nut wrench and it may solve your problem. If the wheel cylinder or any part inside the brake drum has brake fluid on it, the problem is most likely the wheel cylinder seal. The dust cover is just that, a dust cover, it is not a liquid pressure seal. Fluid getting past that came from the wheel cylinder.

http://www.xenonz31.com/s30/reference.html That's a link to a downloadable factory service book. Best to order an actual copy, I got mine from Mike McGinnis at Banzai Motorworks. Drum brakes are pretty simple, read the manual to make sure you have all the right tools before you dig in and make sure to leave one side assembled so you've got a reference. That technique has saved me multiple times!

^ Several American cars have been prone to spontaneous combustion over the decades. Old Chevy trucks, the legendary Pinto, Dodge trucks in the 90's having plastic fuel line elbows that would melt and spray raw fuel onto exhaust plumbing, probably lots of others.

My own z has a light clicking sound that I hear during the last part of coasting/braking down to a stop. As Walter mentioned, it sounds like it's coming from the rear of the car and I suspect it's just one of the U-joints spinning. I can't move any part of the U-joints by hand, which tells me it's not severely decomposed, so if it's getting loose I don't think it's urgent. As for vibration, anything that spins can cause a vibration, and its location and sound are the best things to use to track it down. If your steering wheel shimmies along with the vibration, it's likely a front tire out of balance. If you feel it coming up through your seat but the steering wheel is stable, it's likely a rear tire out of balance. Vibrations that come with a metallic hum can be a drive shaft noise, engine mount noise, rear end noise or any other part that connects one vibrating metal part to another. Check bolts for tight, check U-joints for slop, check the engine oil level (low oil can increase engine vibration that's normally damped out), check transmission/differential oil levels, get each wheel up off the ground one at a time and try to move them laterally/axially to check for wheel bearing slop, so on and so on. For what it's worth, my own car makes a few different metallic hums and drones at various driving conditions, so either that means she's gonna do like cartoon cars do and just explode to pieces and leave me skidding along in a hollow shell on the highway or it means that old z cars are talkative cars and just like to tell their owners what's goin on

If he's the happy owner of a z car now, and he's managed to find a solid chassis, he'll soon forget about whatever minor rust is there as he's fixing failed rubber parts, cracked plastic parts, separated putty seals, broken bolts and electrical gremlins. Ah, the joy of project cars

The J-bolts are in great shape, as are the slots in the frame. Even the straps are barely rusted, most of what I've sanded off is multiple layers of paint and grime. The straps do still have the old fabric stuff, but it's deteriorated and covered in decades of the same crap the straps are covered in so I'm just gonna make new ones. If I had to guess, I'd say the insulation's primary purpose is to prevent metal-to-metal friction between straps and tank which although useful for preventing sparks is probably more useful for preventing gradual wearing of holes in the tank.