Crashtd420 Posted June 27, 2020 Author Report Share Posted June 27, 2020 1 hour ago, datzenmike said: Keep in mind also that the more the belt wraps around the alternator pulley the more it will grip and not slip Would that be a good thing or bad thing? I'm not planning to make a huge S out the belt .... if that makes any sense.... Imagine the straight line between the alternator and water pump pulley.... I want to press down there maybe 1/2 inch just to remove the slack in the belt, then tension like normal..... Does that make any sense? 2 Quote Link to comment
datzenmike Posted June 27, 2020 Report Share Posted June 27, 2020 You don't want the belt slipping. Higher output alternators will resist more when they are charging. This why they did away with the narrow V belts. Well, one of the reasons. Serpentine grip better. 2 Quote Link to comment
Crashtd420 Posted June 28, 2020 Author Report Share Posted June 28, 2020 I'm hopefully gonna get some time in the garage today to check the driveline.... Yesterday the alternator pulley showed up .... Fit really good and let's me use the old nut no problem.... And alignment seems good.... I'm confident I can bolt it up and have the belt aligned, just need to see if I have room to tension or If i have to move forward with my tensioner idea... 4 Quote Link to comment
Crashtd420 Posted June 28, 2020 Author Report Share Posted June 28, 2020 So as far as drive line angle best I can tell is I have a 1 degree seperation.... The tremec toolbox app wasnt to bad, I didnt use it like I was suppose to but more as a digital angle finder.. And the alternator swap went good... I actually was able to fit it without the bullshit of a tensioner.... kind of glad.. Clearance to the pitman arm... Altenator installed.... 1 Quote Link to comment
Crashtd420 Posted June 28, 2020 Author Report Share Posted June 28, 2020 I'm not 100% happy yet with the alternator swap.... I would think a 90amp altenator shouldn't really drop voltage... i do start off with 14.4- 14.2 on start up, then I'm around 13.3 - 13.5. With headlights, 2 radiator fans, fuel pump and a/c running.... I was dropping down to 12.8-13 before..... so it is an improvement ... I still have to get my core charge back for the alternator so I pulled the battery for the hell of it to have it tested..... It measures 12.5 at rest but it is about 4 years old... so I'm just gonna make sure it's still good.... Quote Link to comment
datzenmike Posted June 28, 2020 Report Share Posted June 28, 2020 It's like comparing an SR20DET to an L20B. When idling they make about the same power. 1 Quote Link to comment
thisismatt Posted June 29, 2020 Report Share Posted June 29, 2020 Did you upgrade the positive wiring from alt to battery, and grounds from engine to chassis and chassis to battery? You should have at least 6ga all around, 4ga even better. Is the sense wire still ran like stock? 1 Quote Link to comment
Crashtd420 Posted June 29, 2020 Author Report Share Posted June 29, 2020 2 hours ago, thisismatt said: Did you upgrade the positive wiring from alt to battery, and grounds from engine to chassis and chassis to battery? You should have at least 6ga all around, 4ga even better. Is the sense wire still ran like stock? I have the battery under the bed, chassis ground is 1ga, main power from battery to distribution block is 1 gauge... I think I have 8ga for the power wire from the starter and alternator to a distribution box.... there is a 4gauge that goes into the cab to supply power to everything( fuse panel is inside) and I have a 1ga chassis to engine ground and the alternator has an 8 gauge ground added.. I can easily upgrade to 4 gauge where I have the 8 gauge.. I have some stuff laying around..... And yes the sense wire is ran like stock, in a sense.. I did do the wiring to convert to an internally regulated altenator... 2 Quote Link to comment
Stoffregen Motorsports Posted June 29, 2020 Report Share Posted June 29, 2020 (edited) 4ga wire going into the cab? That's basically small battery cable. 90 amp alternator needs a 4ga wire for anything 6-12 feet from the alternator post to where it ties in to the positive battery cable. Edited June 29, 2020 by Stoffregen Motorsports 2 Quote Link to comment
Crashtd420 Posted June 29, 2020 Author Report Share Posted June 29, 2020 9 minutes ago, Stoffregen Motorsports said: 4ga wire going into the cab? That's basically small battery cable. 90 amp alternator needs a 4ga wire for anything 6-12 feet from the alternator post to where it ties in to the positive battery cable. Ya the 4 gauge to the interior is probably overkill, but it was basically the remaining terminal on my distribution block.... I'll probably reconfigure things a little... 2 Quote Link to comment
Crashtd420 Posted June 29, 2020 Author Report Share Posted June 29, 2020 Just had the battery tested.... Tested fine... they said 12.5 and 85% charged.... I'm gonna leave it on a trickle charger for the night and reinstall it.... And while the 8 gauge wire by the chart should be adequate because it's only 14 inches long I'm going to upgrade it to the 4 gauge regardless..... 2 Quote Link to comment
Crashtd420 Posted July 1, 2020 Author Report Share Posted July 1, 2020 So this morning's drive to work didnt impress me... Maybe I'm over thinking it but I just feel like I shouldn't be seeing a voltage drop.. I know the alternator is coming on, I can see the voltage jump up to 14-14.2 once its started, but it seems to be settling in around 13.2-13.5 while driving... Even if I turn things on or off I dont see it really fluctuate ... the voltage does seem more stable but I feel like it should be closer to 14v while driving.... I upgradred to 4gauge for the wiring to the alternator and starter... checked and there was zero resistance to the cable... rest of the wiring seems good, and I've made sure the lamp and sense are wired properly.. I know I'm comparing this to a newer vehicle and after reading today some say the alternator output is normal ... So I'm really not sure if anything is wrong or not... Gonna run it for now and just keep a mental note of the voltage... 1 Quote Link to comment
DanielC Posted July 1, 2020 Report Share Posted July 1, 2020 (edited) How are you measuring the voltage? Do you know if the voltmeter you are using is accurate? One thing that makes choosing an alternator for a Datsun a little more difficult is the Datsun engine turns a relatively RPM. Because the engine turns a higher RPM than average engines, the ratio to alternator speed to engine speed is a little lower, and this results in the alternator spinning a slower on a Datsun engine at idle than on an engine with a lower red line RPM. If the alternator is not spinning very fast, it does not matter if it is a high output alternator, it needs more RPM to make full voltage output. I just went out, and checked the voltage at the battery with a Fluke model 177 digital multimeter. On my two running Datsun 521 trucks. No, I have not had the Fluke voltmeter calibrated, but I believe it is still more accurate than the typical dash mounted voltmeter. Ratsun was running about 14.59 volts. Dragon was running about 14.36 volts. Both trucks are running internally regulated alternators, with the regulator plug on the wiring harness jumped in two places. I checked voltage at the battery again on Dragon, this time engine running, lights on high beam, heater fan on fast speed, wipers lifted off the windshield, but on high speed, and with four way flashers on. 13.9x -14.24 volts. On both trucks, there is a a ground wire from the lifting lug that the negative battery cable is attached to down to the alternator frame, and the ground wire from the alternator frame to the inner fender where the voltage regulator was mounted. This is a picture of the battery cables and battery in Dragon. I just realized this battery is 15 years old. Edited July 1, 2020 by DanielC 2 Quote Link to comment
Crashtd420 Posted July 1, 2020 Author Report Share Posted July 1, 2020 1 minute ago, DanielC said: How are you measuring the voltage? Do you know if the voltmeter you are using is accurate? One thing that makes choosing an alternator for a Datsun a little more difficult is the Datsun engine turns a relatively RPM. Because the engine turns a higher RPM than average engines, the ratio to alternator speed to engine speed is a little lower, and this results in the alternator spinning a slower on a Datsun engine at idle than on an engine with a lower red line RPM. If the alternator is not spinning very fast, it does not matter if it is a high output alternator, it needs more RPM to make full voltage output. I do have a voltage gauge but to be honest it sucks.... my distributor with the bluetooth connection is giving me a more accurate reading and I verified its accuracy with a volt meter ( which I think is good) I also checked at the battery and various places and grounds while it was idling and I got the same reading everywhere so I dont think it's the wiring .... I dont know if the relocation of the battery is a factor or not.... The wierd thing is when I was idling I noticed the voltage actually came up... I was driving and it was around 13.0, I stopped for gas and when I restarted the truck it jumped up to 14, then settled around 13.5.... once I started driving I saw it drop to 13 again.... Same accessories were on ... headlights, fans and fuel pump... I tried turning the ac system on a few times for the extra load and it recovers and still hangs out at 13.... 1 Quote Link to comment
thisismatt Posted July 1, 2020 Report Share Posted July 1, 2020 Daniel makes a good point - how does the new pulley compare in diameter to what came off of it? Maybe you need a smaller pulley? 1 Quote Link to comment
DanielC Posted July 1, 2020 Report Share Posted July 1, 2020 (edited) "I dont know if the relocation of the battery is a factor or not.... " This is a huge red flag to me. Look again at my battery cables, both have a length of less than two feet, and are 2/0 gauge not 2 gauge. Do you know how to check voltage drop in a wire circuit? A definition, voltage drop is the voltage loss in a length of wire with a current flowing through the wire. A brief explanation of checking voltage drop. In this case, we are checking voltage from the alternator output to the battery positive terminal, with the engine running. With the voltmeter set to volts, put the positive lead from the voltmeter on the positive output of the alternator, and put the negative lead from the voltmeter on the positive battery terminal. The reading should be less than .5 volts, ideally less than .2 volts. Less than a half volt, ideally less than two tenths of a volt. Edited July 1, 2020 by DanielC 2 Quote Link to comment
Crashtd420 Posted July 1, 2020 Author Report Share Posted July 1, 2020 6 minutes ago, thisismatt said: Daniel makes a good point - how does the new pulley compare in diameter to what came off of it? Maybe you need a smaller pulley? I just checked and the old serpentine pulley it was 2.75 od.... The new one is 2.9 inch but the belt rides deeper in the groove vs a flat serpentine belt.... V belt about .375 thick Serpentine about .125 thick.... Would you actually be comparing the od or where the belt is actually riding? Is .200 enough of a difference that it would even matter? 1 Quote Link to comment
mainer311 Posted July 1, 2020 Report Share Posted July 1, 2020 Voltage shouldn’t change much, regardless of load. That’s the regulator doing it’s job. A low battery will cause the voltage of the alternator to start high and then once it’s charged, the voltage will settle to a lower value. Your relocation of the battery might have some small effect on the voltage as previously stated. In my mind, 13.5 is perfectly fine. 2 Quote Link to comment
Crashtd420 Posted July 1, 2020 Author Report Share Posted July 1, 2020 (edited) 2 hours ago, DanielC said: "I dont know if the relocation of the battery is a factor or not.... " This is a huge red flag to me. Look again at my battery cables, both have a length of less than two feet, and are 2/0 gauge not 2 gauge. Do you know how to check voltage drop in a wire circuit? A definition, voltage drop is the voltage loss in a length of wire with a current flowing through the wire. A brief explanation of checking voltage drop. In this case, we are checking voltage from the alternator output to the battery positive terminal, with the engine running. With the voltmeter set to volts, put the positive lead from the voltmeter on the positive output of the alternator, and put the negative lead from the voltmeter on the positive battery terminal. The reading should be less than .5 volts, ideally less than .2 volts. Less than a half volt, ideally less than two tenths of a volt. I just double checked the cable from the battery to the post under the hood... Its approximately 14ft long and by this chart its 1/0.. From the chart stroffgren posted earlier in the post, that should be good..... As far as the voltage drop test I didnt know that.... I'll give it a try this weekend and see if it tells me anything.... Thanks... Edited July 1, 2020 by Crashtd420 1 Quote Link to comment
Crashtd420 Posted July 1, 2020 Author Report Share Posted July 1, 2020 (edited) 52 minutes ago, mainer311 said: Voltage shouldn’t change much, regardless of load. That’s the regulator doing it’s job. That's why I'm questioning things because it is changing.... I know I'm not even close to using the output of a 90amp altenator, I do have future ideas of a stereo so I dont might the extra amperage, but I'm starting to think the 60amp was enough and I do have something else going on here.... I'll try Daniel's test and go from there.... Edited July 1, 2020 by Crashtd420 1 Quote Link to comment
Crashtd420 Posted July 3, 2020 Author Report Share Posted July 3, 2020 I started messing with the truck a little this morning... I swapped one of my fans from a 7" up to a 9".... Tight fit but worked out.... Also came across this... I was checking my grounds and the cable felt floppy,... well the only thing holding it together was some heat shrink... and no I did not solder it... Hoping that's been my issue.... 1 Quote Link to comment
thisismatt Posted July 3, 2020 Report Share Posted July 3, 2020 (edited) Ugg. What crimper are you using? The hydraulic hex crimpers are really cheap these days. I dip the tips of the strands in a little flux, crimp it, then heat with a torch and feed in some solder. Bulletproof 🙂 Edited July 3, 2020 by thisismatt 1 Quote Link to comment
Crashtd420 Posted July 3, 2020 Author Report Share Posted July 3, 2020 22 minutes ago, thisismatt said: Ugg. What crimper are you using? Apparently the wrong ones...... I redid the front and rear ground point with these instead.... All I could find on short notice but they should stay nice and tight and secure.... 1 Quote Link to comment
Crashtd420 Posted July 3, 2020 Author Report Share Posted July 3, 2020 Seems better.... Still need to take it for a drive and turn everything on.... And as I finished that, I came in for lunch and found this in the mail.... For the alternator... using spade connectors right now, I'll be swapping that out soon.... 1 Quote Link to comment
banzai510(hainz) Posted July 4, 2020 Report Share Posted July 4, 2020 I wonder if that batt is charged up it runs at a lower voltage.? running a sense wire is more accurate and should show a accurate reading be honest it should be close 13.8 at least with a little datsun 1 Quote Link to comment
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