pparaska

I've read recently (I have the link at home) that the "til it pings then back it off a few degrees" method of setting initial timing is not always the best power. Of course finding the right mechanical advance curve for an engine is not easy either. Again, I can't remember where, I saw a method for finding the optimum mechanical advance curve. It entailed locking down the mechanical advance system, disabling any vacuum advance system, and driving the car with different initial timing settings. You start with your guess at an idle initial timing setting, test the acceleration of the car (I think a Road Dyno or Gtek would be great for this) and home in on the optimal idle initial timing. Then move up several hundred rpm as you test rpm, put the initial timing (and therefore total timing, since you've temporarily locked out the mechanical and vacuum advance) at a somewhat higher amount, test acceleration and keep testing different amounts of advance by doing acceleration tests starting at that test rpm, and home in on the amount of timing for best WOT acceleration starting at that rpm (or maybe a bit lower?). Repeat for other higher rpms at several hundred rpm intervals. You'll probably be all done by 2500 rpm. Anyway, that's a ton of work, but you'd then know what the optimal power timing curve for the car is. Trying to get a simple device like weights and springs to give that exact curve will probably be futile, but you should be able to approximate it. Of course, you'll need to use the first idle advance number for your initial timing and look at the total change from that number to your highest advance as the change the mechanical advance will need to give, along with it's rpm dependence. From there, you'd play with the vacuum advance for part throttle acceleration in a similiar way, changing the initial timing a known amount and trying part throttle acceleration at different rpms to come up with the vacuum advance curve you'd need. For that you'd need to also note the amount of vacuum. With an adjustable vacuum cannister, you can then try to get close to the optimal vac advance curve. I'd guess it'd take a long day or two to do this, but you'd have tweaked it pretty good. Of course, your carb / FI had better be ballparked pretty good, because leanness might make you artificially have to retard some of the timing curve segments falsely. Wow, EFI with a knock sensor and WB O2 feedback and an intelligent closed loop optimizing function for all that would be a lot easier to deal with! If anyone has a good reference to these kinds of perfomance timing and carb tuning methods, I'd love to see them.

Wow, that's a ton of work. Seems it would be easier to just add additional spot welds between the original ones, and then fill the divets as to hide them. You'd get a good amount of stiffening if there was a spot weld every inch or so. Heck, place 2 between every factory spot weld and fill them in in one swipe of the bondo scraper. For places like the pinch welds in the door opening, you'd want to be careful that the edges of the sheets stayed separated, so it might require opening that up with a stiff putty knife and hammer before doing the bondo work.

I used to run a fish tank type bleeder valve on my Eclipse GSX. This ends up doing much the same thing as the OE solenoid/bleeder - it's always letting some pressure get to the wastegate, and therefore, starts opening it before the bleeder becomes too much of a restriction and makes 99% of the boost get to the wastegate diaphram. Much better is a relief type manual boost controller (MBC). These won't let pressure get to the wastegate until the set point is hit. Low speed torque and driveability is greatly improved over the OE bleeder or the fishtank bleeder.

O.K. Engineer here - better check my math!: (assuming they meant degrees F, and you're at sea level, and the BP of coolant water is the same as water??) Boiling point = 212F + 16psi * 3 deg/psi Boiling point = 212F + 48F Boiling point = 260F So a 16 psi radiator cap gives 260 boiling point?

John I'd like to see that too, just for grins. katman, I suppose you've looked into modelling the difference between leaving the spot welds and seam welding? Even though Z's rust from the inside out, as I was working on the terrible rust in my Z, I found that the spot welds were still quite strong, but the steel around them was the problem. Kind of like, if there's a weld that's nice, but what's it holding together? SInce there can be rust in the metal, say under the area that's overlapped (and rusted ) and spot welded, I'd think that seam welding outside of that area where it's not rusty might tie the car together better.

Dave, thanks for the well informed post. I've been concerned a bit lately since my Z always runs at 210. But that's where the fan switch turns on. It's crept to 215 momentarily in traffic in very hot weather with the A/C cranking, but never above that. I'm fairly convinced that my Camaro radiator is enough, and I run a 195 thermostat to keep the temps up for better effieciency and power.

Hey, I'm only 40! I just went to a small college that had old computer stuff. We also had hardcopy terminals but they were hard to get on (lots of waiting lines) - CRT - well, they wouldn't let us sophomores use those! FEMAP can read almost any FEM format in or out as far as I know. I haven't used it in years but it's hella popular and NASTRAN (MSC?) is too so I'd think it has great support for that. Sounds good to me! I guess being an aircraft dude, you have a few tricks up your sleeve for modeling the fixity of spot welded joints. Damn, I'd love to get back into that stuff. I look forward to seeing that model once you solve the Netscape/SGI issue. Those SGI's rock. I started using them 13 years ago and they were always the best thing for 3D graphics work like FEM pre/post processing.

I have the Momo Competition and I really like it. It has a nice thick grip of perforated leather all the way around, and only two little nubs on the outer diameter at 5 and 8 oclock. Center is black. I have in on a street legal quick release hub mounted to the Momo adapter. It puts the wheel quite a ways back away from the turnsignal control, but I'm used to it and like the position now. It's 13.8" and that's about 1" to 1.5" less in outer diameter than the stock wheel with a cheesy leather wrap. Even with 235 tires on the front and quick steering knuckles, it's not hard to turn at low speeds. I may go back to the stock steering knuckle to make the effort better. The smaller steering wheel, good 45 series tires (Mich Pilot MXX3s at 235/45-17) and quick knuckles make the car very sensitive to steering input. I'd say too sensitive. Between the torque, the steering, and the all-business short throw shifter, it's a very visceral, attention sensitive driving experience. The Momo wheel is really nice and super light, as if that matters. Great feel and looks decent too.

John, I should have been more clear. What I was getting at was if you increase the tire diameter, and rotational inertia by a goodly amount, you'll need more brake pedal force for the same brake setup. That can bring you into a region of difficult modulation if you're not leg-strong. I agree on the system design issue withe master cylinder, wheel cylinder/caliper piston and brake friction materials as well. I think the best reasons to upgrade Z brakes are: 1) add vented rotors to get away from brake fade (you have to decide if you really have a fade problem though!) and 2) add rear discs for either less brake adjustment needs and/or looks with open wheels.

For either R200 (except the viscous one out of the White SS 300ZXT) the methods are the same. Bolt in the Diff, remove (pop out) any side axles from the diff. IF you use the 240Z stub axles the car has and use a modified 280ZX T companion flange set, modded R200 pinion flange seal for the companion flanges, and bolt in 280ZXT CV shafts. Here's a page I wrote on that conversion: http://mywebpages.comcast.net/pparaska/240ZCVHalfshaftConversion.htm If you swap over to 280Z stub axles, then you use the 280Z companion flanges, a CV shaft adapter like Ross Corrigan sells or the one with drawings on my site (below), and just bolt it all in. I prefer Ross's adapters. Here's a link to a page I wrote on that swap: http://mywebpages.comcast.net/pparaska/280ZCVHalfshaftConversion.htm Hope that helps

For the R200 install, the mustache bar needs to be installed with the loops forward of the long part of the bar.

Jim / Lone - I agree with your assessment - a real benefit of doing this would be had if you jumpered across the large lugs on the solenoid. A length of copper bar stock with a good sized cross section, drilled for the two lugs and bent just so would seem to really help. I also agree with Mike that if the S wire to the GM starter is too long, and maybe not in good condition, and/or the connection to the starter isn't good, that the solenoid might not pull in hard enough to get the copper disk that Jim is referring to push against the solenoid terminals in the GM solenoid hard enough to overcome all the corrosion, pitting, etc. that these parts develop over time.

But putting bigger (wider and taller - and usually higher weight and rotating inertia) wheels and tires takes away from the ability of the stock brakes from the get go. If you go to larger diameter tires (outside diameter) and increase the rotation inertia, this adds to the amount of braking force needed to stop the car in the same distance. Also, coming down from speed more often is a result of having more power under the hood. WIth the capability to get going faster, you increase the probablity of needed to stop from higher average speeds, making better gripping and less fading brakes more important. The other issue is modulation for car control. Larger brakes for those larger wheels and tires will probably mean that you'll be able to modulate the brakes better and control the car better.

Incredible. I'd drop that lame service pronto. I wonder if those "support" (or is that jock strap) people like that can actually sleep at night, after feeding you such a line of BS. How about Dish Network, or something like that? Cable modem out of the question?

I just have a gut feel for this, but it seems that keeping something between the mount points is a good idea. I realize that there's a desire to get exhaust clearance, but how about this idea: Cut out the center section, between the control arm mount points, leaving enough material to add a shallower section back between them. If you make this piece out of square or rectangular tubing, with the shallow dimension vertical, you could connect the tow pieces you cut off the ends of the crossmember, leave a bunch of room below the new piece between them, and provide a safety "catch" for the bottom of the diff nose to rest on if the mount broke (I doubt you could break the urethane mount though.)

Mark, well said. I grew up on 60s and 70s American cars and felt unwittingly safe due to the size of them. I'll never forget my boss (and girlfriend's father) in highschool calling my 240Z (yes, I've had it over 20 years!) a "rolling coffin". He looked at the size, then sat in it and just barely fit (he is huge - not fat- just really tall and big). Driving my Z again, I'm reminded of just how close that thin door is. I really feel kind of unprotected driving it - kind of like riding a motorcycle. But that's a chance I'm going to take. I have a roll bar but felt the door bars were too much hassle for a street car that's so narrow and has so little lateral room for a door bar - I mean unless you cut the door interior out, the bar is VERY close to your ribs/side. Plus I didn't (nor would my wife) want to be climbing over them. I guess I'll just take my chances and it'll probably make me drive it a bit more sanely knowing how un-protective it is in a crash compared to most other cars.

Yeah that 240Z is beautiful. I thought I recognized it!

Dude, that looks not so good. But much better than I thought you were talking about. BTW, Zedd Findings is now stamping out rear panels for the 240Z. They've been NLA for many years, and this is a tough piece to get right once it's been smacked or rusted out. Nissan is also selling the part that goes in the lower hatch opening. I think a decent body shop can fix that well. My car looks to have been hit just like that many years ago. I see evidence of the same damage, all but the floor inside the hatch totally fixed. Are the 1/4 panels o.k.? Anyway, I hope that gives you some encouragement. It must be a real downer to see your Z like that.

Yes, the epoxy paints I've seen for this all talk about USP washing and etching with acid. These steps are imperatvie to having the paint stick! This is a big job to do right. And make DARNED sure that it's not going to rain for 24hours afterwards as you need to leave the doors and windows open for that long. The fumes from the epoxy paints are really bad for you.

LT4Justin, "you're a goddamned genius!" (To quote one of my all time favorite movies!) I laughed when I saw that! I must say I feel much like your comment, although I'm not sure if you were just joking or felt its alright to leave the stock taillights be...mods are cool too though! Terry and Eric, your discussion of breaking up the rear of the car, the need for horizontal "features", etc. rings true for me. Eric, I'd really like to see some sketches of this triangular layout of round lights. Sounds interesting. At the MD Z club cruise-in I attended this past weekend with my car (first time the club had ever seen it), the president of the club - someone who absolutely LOVES stock Zs - was complimenting my choice of painting the rear filler taillight surround panels the same color as the car. He said he'd been suggesting that to owners for years and really liked the look. That's kind of different than ADDING things to break up the back end, although the undulations of the panel do that well enough, as does my diminutive bumper, even though it's body color. I just thought it was interesting that someone who is very into STOCK Z's liked that "updating" touch on the rear panel and it kind of fits in with some of the rear styling topics being discussed in this thread.

Cool! This is great info for anyone that finds a 300ZX LSD and doesn't want to swap the flange or try to find the flange that goes with the JTR spec'd flange! Of course, you'll need to clearance or remove the crossmember, but with a Ron Tyler type front diff mount that's not a problem! Way to go! This is FAQ material, jeromio!

This talk of rejuvinating tires is interesting. The Micheln Pilot MXX3s on my Z are probably 5-6 years old, but have little wear. I need to get a durometer, but a road racing buddy stuck his fingernail in them and said "they're ROCKS". Mike Kelly said the same thing. What's the deal with this "Formula 1" stuff? Will it ruin the tires (make them wear out quicker, or something)? Does it work? Anybody with experience with this stuff, I'd like some opinions. Thanks,

I agree with katman that the seam welding is probably of little use. I only did a little bit of it. Katman, I do remember the Univac. I used to program on one with cards - yes, the good old computer cards. Thank goodness I never did anything like do an FE model on cards though! Talk about a nightmare! PATRAN huh. I used to use that when it was it's own company. If you do it, how about a FEMAP translation so us people with access to that can "borrow" it . Just kidding. How detailed are you getting with this model? There are alot of little details, like the spot welds, beads, etc. that would take forever to model. Of course, the problem is always finding what to do in detail and what to simplify. I usually erred on the detail side since since I hated doing convergence studies for lots of iterations. I'd LOVE to see a wireframe or shrunk element view or two of that when you get it done!

Mike, I'm glad to hear that. My 327 with moly rings and forged TRW pistons (the heavy slugs that take 0.0020" clearance) is still burning oil at 500 miles. It's gone through 1.5 quarts in that time. I'm hoping it will slow down soon. I'm going to wait until it does before switching to synthetic.

Terry, if I understand the placement of the diode as described above correctly, I agree it would not help for the reason you state. Besides, diodes don't like to take alot of reverse current if it could be connected in some fashion to block the back-emf anyway. I only use them to block low current sneak circuits.