zredbaron

Bump. I know, this topic has been in many threads before, but all my searches yielded results like "a buddy of mine has such and such tire with stock springs" or "yeah, that *should* clear" or "rubbed fenders, but i think that was because of ___." I am looking for solid experience, not just speculation. I can speculate with a ruler, but we all know that doesn't always work. I know that several of us have Ross's honda wheel spacers/adapters with coilovers. I know that my 225/50R16s fit. Does anyone KNOW if anything wider than that fits, front and/or rear? Thanks again.

I have Ross's coilovers with his honda wheel spacers (4x100 if my memory serves me). I currently run 16"x7.5" wheels with 225/50R16 tires on the street (works wonderfully). My only body mod is a motorsport polyurethane air dam. I'm looking into getting a new set of wheels/tires for autoX / road racing use only. I was thinking 245 tires would add some grip. Surely some of us have tried this with these wheel adapters...results? Anyone have >= 16"x8" wheels and/or >= 245 tires? What's the limit without rubbing fenders? (I'm sure 245s up front would cause problems with u-turns, that's ok...race use only) Thanks in advance.

great feedback, as usual guys. that was exactly what my old mechanic said... that his lap times dropped about a second and a half (he also added that it felt weird to drive, but it worked). i think Jon is right though, i'm probably getting ahead of myself. i've never autocrossed before, and i should start learning how to drive before i start experimenting with my car. i'll definately keep all of this in mind when that time comes, though. one variable at a time, please.

it IS nice to finally get some more power. and i think 45DCOEs would realize more, too. the weber chart says i should be at 38-40mm venturis, but i suspect 42mm may even be in order since the sunbelt head probably flows a little more than that graph is figuring... johnc, interesting you should mention that bit about suspension being setup to match it. i was just having a conversation with my old mechanic (who raced Zs in the 70s) and he told me that he once saw on a videotape that his rear inside wheel was coming off of the ground (obviously welded diff....i doubt quaife existed back then) (i sure as hell didnt! ). he said he fixed it by taking the rear sway bar out completely and having a 1" bar up front. any experience on that matter with the quaiffe? whats your setup? im taking an autoX class next friday and the instructor will help me tune my setup a little...

kooneon, i was 19 when i dropped a 3.1L in my 240Z (1999). i had high expectations. i think this is the answer you are looking for...and what i wish i knew at the time... my 3.1 had an unported/unpolished head with an average cam on it at first, passably tuned triple webers, an excellent direct ignition system, and slightly restricted exhaust (headers + flowmaster). this setup produced a dynoed 131 rwhp (157 ft-lbs)... ~L24 oem performance. i could barely peel out with an open diff and 205 tire width (i really had to get the rpms up and drop the clutch). even then it would only peel for a second or two. i was astonished and humiliated by the numbers. all that money on the 3.1...for what? but the dyno didnt mean anything...it simply told me i was restricted somewhere else. by dialing in my ignition curve over 9 pulls, i was able to get up to 157 rwhp and 176 ft-lbs, just by adjusting my timing. so....this should be an excellent example of just how important the big picture is. a good head and carb tuning to realize the head's potential are very, very important. dont forget ignition, intake, and exhaust can all be weak links too. dropping in a very well built head gave me ~50 hp (dynoed) right off the bat. opening the exhaust, getting bigger venturis for my webers and dialing the the jets has probably yielded another 50 hp (undynoed). i currently have 36mm venturis, and the weber chart shows i should have 38-40 for max power. i suspect 42 may even be applicable for me since im trying to feed the potential of a Sunbelt head. but i need 45DCOEs to go bigger than 36. at the moment, i peel 1st and 2nd if i ever floor it. two days ago i snapped a u-joint downshifting into 4th at 80mph. i haven't touched the 3.1 block at any point in my engine's evolution. it's all about realizing it's potential. driving a ferrari doesn't mean you will bring a beautiful woman home with you. you just have more...potential...

just a quick glance at this thread...but is it possible that the gauges can only measure static pressure? bernoulli's principle: as fluid velocity (flow) goes up, fluid pressure goes down... in theory it could be in the realm of possibility that your gauges are correct...which is why your car still runs...flow is happening...

ah hah. so while u-joints should be ok for me at autocross (i'm definately not making over 300 hp), the drag strip may tear them up. the zxt CVs would actually be stronger than the u-joints, and smoother, too. so basically unless i do the conversion, stay away from drag or take it easy if i do go there. the last time the two of you tag teamed a thread of mine (head discussion) i learned a lot (and got a sunbelt head!). thank you both so much. again. john, that is a sexy picture of that Z with that front tire just off the ground. somehow i think i'm just a few thousand dollars away from that level...

thanks, john. perfect explanation...understanding why will help me prevent future mishaps. so...the intended use of this car is autocross. i may go to the drag strip a few times, and I also drive the car to work frequently. if this were your car, john, would you keep the u-joints or would you go with CVs? i would like the less vulnerable solution, i intend to jump hard on the pedal after coming out of a turn. and in the case with the gts-r viper, how are u-joints more reliable, and why is there a power difference at all? (and yes...rudypoorchris, sure it was possible the engine bogged. it was very fast. my logic would agree that it likely did from the rich condition. my butt just doesn't think so.) thanks.

i very much recommend renu. see pics of my 'fuel tank not filling' thread active in this forum.

thanks for the clarifications. rudypoochris, after my explanation do you still think it was decel that caused it? (i realize at this point i'm probably making a mountain out of a molehill...sorry) Ed - my jets right now would appear quite odd. Since installing an A/F ratio gauge, I've discovered I have a problem running extremely rich when the outside temp is above 85 and humidity is > 50% (east coast sucks i have to tune three carbs for temp AND humidity). It was really weird...even if I dropped my main jets as much as 30, it wouldn't lean out. After ruling out incorrect float levels, I finally determined my fuel pressure was too high (6 psi when it should be half that!). I have a pressure regulator on the way. But...when its nice out...75 degrees and low humidity...it runs beautifully with the following setup: 36mm venturis 140 main (trying to lean out my rich condition) 220 air corrector (i know, big jump...but it likes it) 55F8 idles My theory on the air corrector jet needing such a large jump is a resultant cross between fuel pressure being too high and the head flowing so well. And let's be honest, my 25 year old lead foot isn't helping any. Heres a pic of my guage install...

just when I thought I was understanding, now I feel like I'm missing something again. either that or i am being misunderstood as to what my feet were doing. either way, i'd like to clear it up...i want to know if i'm looking at something all wrong or if its just a simple miscommunication. you say my tires lost traction to catch up with drivetrain, then i hammered the gas. this is where i think the confusion is....there was never a decel, the shift was as instant as it gets...i think any decel would be negligible: i pushed in the clutch, and yes, im sure there was a *slight decel* as the shifter went from 5th to 4th, no slip in traction yet...the clutch is still in, then i simultaneoulsy let off the clutch and mash the pedal. this is where the chirp occurs...definately under accelleration, not decelleration. this all happened in less than half a second. not much decel can happen in half a second with the clutch pedal in. drop in torque felt on the rear drivetrain, sure, but decel? any decel would be from drivetrain friction and road friction (wind resistance slowing car speed and therefore wheel rpm), the engine would not be doing a forced decel. this decel wouldn't be anything more than negligible for all intents and purposes. not in my train of thought, anyway. 13 lb aluminum flywheel, carbureted. i did NOT raise the rpms and let out the clutch. the drivetrain was engaged at the same time the pedal was pressed. i assure you it was throttle response and not excessive kinetic energy at the flywheel. the setup is very torquey (sp?). really?! do you mean the 240Z or 280zx oem u-joints? or either? i think i'd rather find a way to do an r180 cv conversion rather than put in 280zx halfshafts... thanks, guys. (and perhaps I should be shot for this...but I'm tired of wondering what IMHO means...what does it mean?)

Great explanation, Pop N Wood. Between your and the others' response, I feel like I have a much better picture of what's going on back there. Thanks. Thanks for the compliment...I try and keep the car clean. I should update that picture, I've got an air dam now.

awesome. thanks, jon.

Thanks! Although there are a few out there that are even more baddass.... Speak of the devil! Haha, thanks John (and Jon M). I missed you guys, too. So, I see now that 'I was asking for it', but I am not 100% on the details. I know that causes a lot of stress on the drivetrain, but why did it break in that scenario, and not during full accelleration from 1st to 2nd (the tires slip for more than a chirp, and lunge the butt-dyno quite a bit more)? Wouldn't this stress with the wheels at a lower groundspeed be more devastating for the drivetrain? Or did I just find the straw that broke the camel's back? As for CV joints...I am interested in the swap. I went to the MML website and all Ross' adapters are for R200s. Am I screwed with my R180? I've invested so much $$$ in it that I'm not willing to go to R200. If I do manage to do the CV conversion, will putting this kind of stress on the drivetrain be...'more acceptable'? Let's be honest...it's a lot of fun and I'd like to be able to do it without hurting anything but my tire tread. I've seen pics of CV halfshafts, they look like are wouldn't be any play in them...is this true? Please comment on my conceptual errors! Thanks, guys.

hmmm...if i understand you correctly, you are under the impression i used the downshift to slow the car. i was cruising with slight pedal in 5th at 80, then simultaneously downshifted and floored the gas as i let off the clutch to engage 4th. i doubt there was any decelleraction of the drivetrain, just accel. or am i wrong? i dont undertand what you mean by "the U-joints are just as strong as the CV's until the rear is squating hard getting the U-joint out of alignment." thanks.

okay, so I was under the impression that an NA L6 would be okay with spicer u joints, evidently i was wrong. i was trying to entice a ferrari to show me up...we were cruising at 80mph. i downshifted into 4th to make the tires chirp, lunge forward and show him i might me worthy. i slow back, look at him, he nods, i chirp again, but this time a loud pop and lots of banging. oh yeah and a tow truck. and now my wheel well is beat to $#!+. so... i must ask. is this odd, breaking a spicer-u joint in this fashion? it seems odd to me. (i always thought if it would happen, it would be between 1st and 2nd!) is this a fluke or do i need to do the CV conversion? i have the r180 4.375 diff with a quaife atb inside. are there any other benefits to doing the CV conversion? thanks, mark

heres the one i have. works great to restore brake power with aggressive / radical cams... http://store.summitracing.com/default.asp?Ntt=vacuum+canister&x=0&y=0&Ntk=KeywordSearch&DDS=1&searchinresults=false&N=0&target=egnsearch.asp

i recently had my fuel tank sent out and coated (lifetime guarantee, yes i've been warned by experienced mechanics) due to rust powder clogging my fuel system. while i was at it, i replaced all the old hoses, vent system included, with new hoses. since then, gas pumps' auto shutoff feature stop at ~3/4 full tank. if i *slowly* keep filling/topping off, i can get it full all the way. the new vent hoses were not pre-shaped like the stock ones. the only theory i can think of is that one or more of these hose turns has been partially kinked trying to make a sharp turn. can anyone verify my theory? would that cause the problem i'm having? thanks! (heres pics of the fuel tank coating if anyone is interested) p.s. been gone a long time....lots of changes! me likey!

i know, i've heard it several times....the 81-83 5spd trannies are identical. i just want to make absolutely certain that the internals are identical...i am having what i believe to be an 82 *could* be an 83 rebuilt, and a shift fork needs replacing. so, i figured i'd dummy check this one with you guys... thanks, mark

awesome! thanks steve! with the gear ratios you show for 1st and 2nd gears, i probably shouldnt go with it. i have a 4.375 R180 with a Quaiffe ATB and it already spins in first gear with 2/3 pedal. that tranny would just make me spin em easier... glad i asked! thanks again... -mark

i got a guy telling me a 5spd he wants to sell (from a 84 maxima) will bolt up to the z car....is he right...anyone know? anything else i should know? thanks guys.

I couldn't find this simple fact in a search...sorry if I just didnt see it. I am under the impression that the 81-83 5spd trannies are the same, regardles of turbo or NA, 2 seater or 2+2... am i wrong or am i right? thanks guys.

Dave, No worries for the "delays." Wasn't long anyway! I very much appreciate the detailed response. It cleared up a few things I was very close to grasping. As for my distributor, I don't have one. My ignition is direct, using three coils to send spark based on crank position. This is why I can plot a curve like you saw in that graph, and also why I don't have a vacuum advance. As for finding someone to tune it, I'd like to learn to tune them myself. I used to think that one day I might switch over to a TWM 3x2 throttle body setup, but now I think I might just go for the 45 DCOEs. Especially since I finally am starting to understand what the different jets are controlling. I like your idea of an O2 sensor. Do they mount in the intake manifold? The exhaust? Why the F9 idle jet as opposed to the F8? One last question: suppose I swap some jets and the car runs a lot better. Does that also shift where my timing should be, or is that strictly dependent on the cam? Thanks again, Mark

Bill, The runs started at 2000 rpm because with the cam I have and the jetting as it is, the car doesn't do so well down there. The dyno runs started at 2000rpm with light pedal and transitioned to full pedal by around 2500rpm or so. Full pedal till the end of the run. My idle rpm is about 1000. I had 55.F8 idle jets in the car, and it was too lean (did a nose dive under 3000 rpm). I have 65s in now...perhaps 60 would be best. Here's the power curve: As for gas mileage, I have no idea. I just did a head swap, and haven't driven it enough to tell you. I was getting 18-22 before the swap. Not sure how relevant it is but my head flows 200cfm (lift .520", duration is 290° for intake, and 274.8° for exhaust). Compression: ~11:1. Thanks for the help!!! -Mark P.S. Scott, are you willing to part with any of your jets? I would love to get my hands on a decent collection so I can play with them on a dyno...