kully 560

yes, those are the ones! they were no longer available at msa. they did not know the thread size after I ordered the new bumper stops yesterday. thanks for the help.

does anybody know the thread size for holding these bumpers on. thanks

ok thats what that was thanks

hi Steve, when he started the car, he had a little voltmeter in there that was reading 14.2-14.4 volts. did you install the upgrade alternator in your z and left the ammeter?

hi Yarb, the fan does have a 30amp relay feed directly from the battery! and thanks Steve, for the video on the internal regulated alternator install. I did replace the alternator about 2 years ago with a 40amp version, but that was all that was available at that time with the pandemic. I did order it at Rock Auto after I read Zed Heads reply back this afternoon about the 280z 60amp alternator. it was the last one in stock, so I jumped on it. I did watch the entire video and saw he has a voltmeter in the car, but my early 260z still has the amp meter. I would have to look into that down the road if the amp meter gauge would need to be changed with a 280z voltmeter gauge. I do believe I would need the voltmeter gauge to complete the upgrade. but for $23.00 right now for the 60amp alternator it is not a big loss if and when I do decide to make the change down the road. thank you.

yes, this also through me for curve ball. I think the spall electric fan was just too much current draw at the low rpms. I will look into the bigger alternator and see if rock auto lists the 60amp version! thanks

thanks Zed Head for the help!!! I did take your suggestion today. I used the blue wire at the coil and with the early 74 ingition module removed. I had no continuity from the blue wire to the signal wire at the tach. I did try wiring direct again from the msd 6a tach output to the back of the tach and it works great. now when I did try that before, I was using the fan override switch in the cab to turn the fan on and the tach would drop, but I never let the engine warm up. [ too much load] now when the engine is cold it will idle at about 650 rpms and when fully warm up it will idle about 850 -900 rms. so with the lower rpms it looks like the alternator was not putting out enough. I am still using the stock charging system with a 50amp alternator, and also using the external voltage regulator. but I still can't use the electronic flasher, could be with some 90% led bulbs, but that is no big deal. thank you very much again for your help. you are a great forum member. kully

I did find the problem today with the tach bouncing. I removed the cec electronic flasher for the turn signals and the hazard lights and no more bouncing of the tach with the turn signals and hazard lights. I did reinstall the oem niles flashers back in. now I wired the msd 6a tach output directly to the tach and it does work fine. except when the cooling fan comes on it does drop at idle about 400 rpms momentarily. I then wired back in the v-booster and had to use 3-100k ohm resistor in parallel so I would get 33.3 ohms total between the v-booster tach output and the tach input, and everything still works great but now when the cooling fan does come on the rpms only drop about 200 rpms momentarily. making headway!!!!

let me see if the resistors have any effect tomorrow when they get here that should give me better in site. maybe that 2.2k ohm resistor in the wiring harness has some effect. I did bypass it with the direct wiring from the tach to the msd. my wiring is clean, as being electrician for 40 years, nothing is hacked but maybe I did miss something, we are never too old to learn something new. thanks

the turn signals effect the tach also when the fan is not running, the tach bounces with the turn signal.

I did install a separate fuse block next to the battery with 6 circuits. all of my aftermarket stuff comes from that fuse block. including the fan, fan controller, msd , and fog lights. everything in the cab runs off of the interior fuse block.

I tried the msd tach output wired directly with the tachometer and it does seem normal rpms and no bouncing at all. except when the cooling fan comes on, I do get a big dip on the tachometer. It must still need a resistor and not the technoversion v-booster. which all it is doing is raising the voltage signal and I am lowering it with the resistors. I have a 1watt resistor kit coming tomorrow from amazon and I will put the stock 2.2k ohm in line with the msd output connection and the tach input connection and see if that corrects the drop under current load. if not, I will have start testing different resistor values to see if I should be able to correct the drop. thanks, everybody for the help! and Zed Head for the heads about the no pulse from the msd tach connection that was a good call.

now if the msd bypasses the multiple spark output on the tach output connection, which I did not know it would be worth a try!

I did tape up the blue wire by the coil, and I did run a single wire from the msd tach output directly to the tachometer.

yes, it should be lower with the resistor.

I do have the blue wire taped up neatly in the harness by the coil, but I can read it from the tachometer side. good idea, I do understand that the oem system and the msd are both square wave except the difference is the msd pulses at idle correct, which would still cause the tachometer to bounce at idle. maybe for the heck of it I will hook up the msd tach output directly to the tachometer and see what happens, all it can do is bounce I believe. thanks again

also Zed head that there is a 2.2k ohm resistor in the wire harness on the passenger side front kick panel where the oem 260z ignition module is located. I believe that is also for the tachometer circuit. I which I knew what voltage signal Nissan was looking for?

I did read on the net that there was somebody explaining that he removed a resistor from the back of the tachometer which would have lowered the voltage on stock systems and then installed a jumper to bypass the resistor and the tachometer worked great. but my dash cover will not let me remove the tachometer from the front. I do believe that the rpm idle bounce is from either noise or the msd 12v pulse. it just seems crazy to use the voltage booster to increase signal and then use a resistor to lower it somewhere between the two voltage points. if I do find the point where it works perfect with a little change in resistor value, I might leave well enough alone. the tachometer is basically a coil, but what voltage was it designed to operate on?

hello Zed head again, I don't know why but I thought with the msd 6a ingition you cannot wire the tach directly to the coil because of the 12v idle pulse? now the reason for the resistors is in the technoversion v booster the signal is a little too high and the tachometer runs about 1500 rpms higher than normal. now with a resistor value of 35.2k ohm the tachometer was spot on with the rpms except for the electric cooling fan surge. that is why I tried just for the hell of it to lower the resistance valve just to see what happens. and bingo at 31.7 k ohms the tachometer was steady when the fan came on except for the little load the alternator creates. I did have just a little at idle rpm tachometer bounce which I think going up just a little in resistance would fix that issue. am I going in the wrong direction? do you think I should wire it direct to the msd with the 12v idle pulse?

it definitely looks not centered!!! glad you might be on to a cure.

well, here is my update today. I changed the resistor value from 35.2k ohm value to a 30.7k ohm value and the tach rpm stayed accurate. the tachometer never changed when I did turn on the electric cooling fan which is a good sign. but the msd was causing the tach to bounce a little at idle. now I did just order some more resistors to have a 32k, 33k, 34k ohm values on hand to play around with. it does seem I am getting close to maybe getting it right. I was a little afraid to hook up the msd 6a tach output directly to the tachometer as the pulse at idle was still making the tachometer bounce with the 30.7k ohm resistor. with the 35.2k ohm resistor I had no bounce. I think I need to find the right value between the 30.7k and the 35.2k ohm resistor.

yes, msd makes the 8910 and the 8920. the 8910 is for the early 240z cars with current driven tach, and the 8920 is for the 260z and up with voltage driven tachs. I will try and come off of the msd tach wire and go straight to my tach and see what happens. I do not think it will damage the tach as it is still voltage. if that fails I will have to play around with different value resistors and see how that works out. I will update as this goes on. thanks for all the help

thanks Zed head, I did read that and that is why I choose the v- booster. on the early 74 260z the tach blue/white wire did connect to the ballast resistor if I remember which limited the voltage. the msd does put out 12v but on an oscilloscope it is only about 3-3.5 volts. that is why when I read the online info you found at the technoversions site about the products, I thought I needed the v-boost, but it does seem to be too much in voltage increase.

I do understand what you are saying Steve, but I have a separate fuse block new next to the battery for the fog lights, msd ingnition, and electric cooling fan,also new key switch ect. maybe I will try going from a 35k ohm resistor to a 30k ohm resistor and see how that works. I just might be limiting a little much voltage. but with resistor change comes the rpm change which is spot on. I thought about the diode to help with the current draw so it might not fluctuate but you seem to think it will not help. I do need to be care full as to not damage the tach, I do have a dash cover I installed 30 years ago, and the tach can't be removed from the front anymore. now I really don't want to pull the dash for a new tach install. thanks