432-r Posted February 24, 2012 Share Posted February 24, 2012 (edited) Hi, i was hoping for an answer on nissan tachos. i know people speak of the 280z tacho as an upgrade over 240z. That is written quite a bit. But if a 240z tacho is functioning perfectly is a 280z one still better? with the different pickup - does this mean more accurate RPM and less rpm needle lag? most people change if their 240z tach is stuffed but i was looking for a opinion on if it truly is an upgrade on a good 240z one. i.e. does it track rpm faster (eg when flick throttle or accelerate); i am guessing an aftermarket electonic tach is still far better? i have a zx dizzy. cheers, Peter Edited February 24, 2012 by 432-r Quote Link to comment Share on other sites More sharing options...
_Donovan_ Posted February 24, 2012 Share Posted February 24, 2012 I can't say for sure what all reasons the 280Z tach is better but I do know that it is needed for the v8 swap due to the internals being different. All the other things you mentioned I have no idea about. I also did not see many if any topics about a 280Z tach being better than the 240Z but then again I was looking for anything like that since I already have a 280Z. Quote Link to comment Share on other sites More sharing options...
piston Posted February 24, 2012 Share Posted February 24, 2012 You will hear many different things from many different people. IMO the factory 240z tach is the one you will probably want to keep for your car if it has the original 240z engine. It is made to read that tach signal off the original engine. Aftermarket tach is not always accurate as some people may think. I don't think a aftermarket tach that can read 4,6,8 cylinder is any better compare to the factory oem tachometer. Factory tachs are design to pick up and display the most accurate rpm possible for the engines installed in that chassis. Quote Link to comment Share on other sites More sharing options...
432-r Posted February 24, 2012 Author Share Posted February 24, 2012 (edited) Over in Aust our 260z has carbies - and points ignition so has the same tacho "setup" as 240z. So a 280z tacho install changes things to a negative (trigger) pickup.(also running the zx electronic dizzy) The look of 280z tacho is the same as is the RPM range (260z same as 280z in stroke). I am thinking that this trigger pickup actually means that the tacho is technically 'electronic' and is as good as any electronic tach (within reason obviously). Basically more accurate than the old + pickup current 240z tacho, and is stable under full voltage, and depicts accurate rpm. thats what i am hoping at least, but dont actually know. i am doing some head work and the car is going to be revving harder now so when its up in the happy zone i know accurately what the motor is revving at. Edited February 24, 2012 by 432-r Quote Link to comment Share on other sites More sharing options...
getoffmyinternet Posted February 24, 2012 Share Posted February 24, 2012 (edited) The 240z tach isn't wired to the distributor directly, it's more like a gmr pickup where the wire passes through it and the field created by the pulses is measured. Electronically speaking, it shouldn't be any less accurate, nor should it lag. The lag/accuracy would have to be in the mechanical construction of the tach, and it seems that the 280z version hadn't changed much. People switch to the more conventional 280z tach because the old version is more finicky. I tried to get mine to work with my swap but couldn't for the life of me get it to pick up anything other than the original wiring. I ended up getting a universal tach and a gmr pickup, the headache just wasn't worth it. Either way, if it ain't broke, don't fix it. I don't think the 260z tach is the same as the 240z even if the setup is the same. They did away with the funky signal input after the 240z. Edited February 24, 2012 by getoffmyinternet Quote Link to comment Share on other sites More sharing options...
beermanpete Posted February 24, 2012 Share Posted February 24, 2012 (edited) The early 4-wire tach has a calibration trim pot in the back so you can calibrate it if needed. I do not know if the later type has this or not. I repaired and calibrated mine and it is fine as far as accuracy goes. I don't like the needle bounce however. It takes too long to settle after a shift. Edited February 24, 2012 by beermanpete Quote Link to comment Share on other sites More sharing options...
432-r Posted February 24, 2012 Author Share Posted February 24, 2012 thats the thing. the later one (as i read) does not suffer needle bounce due to being able to handle a full 12v and running off the negative pickup. Thus by definition (all else equal) should keep things a bit more accurate. Mine occasionally bounces as is, and it annoys me. not often. Quote Link to comment Share on other sites More sharing options...
Heroez Posted February 24, 2012 Share Posted February 24, 2012 the 260z tach is best because internally its the same as the 280z but the face has the correct carb redline. The 280z tach has its redline 500 rpm lower due to the increased displacement. Quote Link to comment Share on other sites More sharing options...
Leon Posted February 24, 2012 Share Posted February 24, 2012 the 260z tach is best because internally its the same as the 280z but the face has the correct carb redline. The 280z tach has its redline 500 rpm lower due to the increased displacement. The 260Z tachs, at least the early ones, were the most prone to failure. Just search around on tach failures and you'll see this. My 260Z had the tach die, so I put in a 280Z tach and it's worked like a charm since. The 260Z was the first in line to get electronic ignition and it seems as though there were some teething issues with the tach, which were then solved by the more robust 280Z tach. If you're concerned about face-plates, those are easily swapped. Quote Link to comment Share on other sites More sharing options...
Heroez Posted February 24, 2012 Share Posted February 24, 2012 (edited) I have read that now that you mention it. My 260z tach is fine, so I dont believe everything I read. There is so much bad information floating around I trust my experience first. You are right about swapping the face. As for the internals, they look the same as the 280 ones. Eyeballs like butt dynos are not accurate in any measurements. Oh, windex will remove the paint on the gauge face. Use a dry cloth only! Edited February 24, 2012 by Heroez Quote Link to comment Share on other sites More sharing options...
Leon Posted February 24, 2012 Share Posted February 24, 2012 I have read that now that you mention it. My 260z tach is fine, so I dont believe everything I read. There is so much bad information floating around I trust my experience first. You are right about swapping the face. As for the internals, they look the same as the 280 ones. Eyeballs like butt dynos are not accurate in any measurements. Oh, windex will remove the paint on the gauge face. Use a dry cloth only! I don't believe everything I read either. However, when searching about tach issues, I noted that the highest percentage of reported failures were 260Z tachs. I don't consider someone saying that the tach is broken in their 260Z as bad information. Quote Link to comment Share on other sites More sharing options...
Heroez Posted February 24, 2012 Share Posted February 24, 2012 Observations on what is what written several times, and what is written is what I doubt. Ive seen people swap out their bad tachometer with a known good one (and other parts) just to end up with the same problem. Some people troubleshoot, others guess and swap parts. Is the tach bad? Maybe. I cant say unless I can look at the tach and its associated wiring myself. I can speculate only. I like the stories about blown fuses myself. "Every time I replace the fuse it blows out." That is because the fuse is doing what it should, you likely have a short. It always makes me chuckle. I wonder how many fuses it takes before they realize they are not fixing anything. Quote Link to comment Share on other sites More sharing options...
rejracer Posted March 25, 2012 Share Posted March 25, 2012 I have the 280z tach in my 240z. I only did the upgrade because I upgraded to the ZX distributor. As far as accuracy, it's off at idle, accurate at 2500 and off anything above 3k. In other words, it's not accurate. I think it's adjustable with the potentiometers on the back, but have not bothered. IMO don't upgrade to a 280z tach unless you need to, it's not really an improvement over the 240z tach. Quote Link to comment Share on other sites More sharing options...
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