Dat73z Posted February 7, 2023 Author Share Posted February 7, 2023 @calZ they are all poly and spherical bearings. This evening I hung the exhaust and finished checking the torque on everything. I then torqued the lug nuts and proceeded to crank for oil and fuel pressure. It seems I need to reset my float heights after the needle and seat swap as some fuel was overflowing into the AVs on carb #3. I'm out of time for tonight but tomorrow I'll fire it up and heat cycle everything. Burp the cooling system, check carb sync, recheck the torque on all the vbands, let it cool then put the surge tank back on for boosting. Quote Link to comment Share on other sites More sharing options...
Dat73z Posted February 7, 2023 Author Share Posted February 7, 2023 This AM I started back in on the carbs. It seems the initial pressure wave when triggering the fuel pump on causes the float bowls to slightly overfill. Then at steady state they maintain level. Or at least that is what I think I'm observing. I believe with the greater seating area of the 2.5 versus 1.8 needle and seat, more force is required to open but I'm not sure about closing force. Either way, these are fairly standard parts and everything was working fine with the 1.8s so I'll play with it more later today as this is the last thing required for a running and driving car. Quote Link to comment Share on other sites More sharing options...
Dat73z Posted February 8, 2023 Author Share Posted February 8, 2023 Unfortunately my schedule has been getting crazy this week but I needed to move the car so I set the float heights to 28mm (spec is 29...for slightly earlier tip in) and the engine fired right up after the 2nd crank. I noticed the 2.5 needle and seats are much more sensitive to adjustment than the 1.8s but I got them dialed in. It seems to be running smoother than it was and sounds healthier. But it's been a few months so I don't fully recall. If I have time this PM I would like to burp the cooling system and heat cycle everything but we'll see how the rest of the day pans out. 20230207_161111.mp4 Quote Link to comment Share on other sites More sharing options...
Dat73z Posted February 8, 2023 Author Share Posted February 8, 2023 Since I went for a short drive yesterday evening this AM I performed a quick inspection for leaks. Everything seems bone dry. I'm hoping later today maybe over lunch I can heat cycle out the car. I've been running into timing issues where it's either too early or too late to fire up the car and run it for a few fan cycles since it's so loud. Quote Link to comment Share on other sites More sharing options...
Dat73z Posted February 8, 2023 Author Share Posted February 8, 2023 (edited) Today over lunch I ran the engine up to operating temp and went for a drive NA. Had some issues with the 2.5 needle and seats again so went back and recalibrated everything again- hopefully this will not be a recurring theme. The balance between all 3 carbs was pretty close to where it was last spring with some minor adjustment. As I remembered, carb 2 has some slight imbalance issues due to overextending the linkage when I was setting WOT with my wife at the pedal (oops). I will fix that next season when I have the carbs back off for the next service. I'll let the car cool this afternoon and hopefully this evening I'll get the surge tank back on and be boosting again tomorrow. Edited February 8, 2023 by Dat73z Quote Link to comment Share on other sites More sharing options...
Dat73z Posted February 9, 2023 Author Share Posted February 9, 2023 This evening I got things mostly reassembled and took the car out for a shakedown drive. The alignment is slightly out now which was expected. I should probably order some new tires and book an alignment, but I'm wondering if it's worth it to wait for my new wheels to be finished. The tune is also slightly out. I had it silky smooth before the car went down and now it's jerking off throttle under vacuum and the idle is slightly high at 1.1k rpms or so. So I'll start by rechecking the timing and ensuring mechanical tdc is set correctly to the distributor. Quote Link to comment Share on other sites More sharing options...
Dat73z Posted February 9, 2023 Author Share Posted February 9, 2023 (edited) Mechanical TDC looked good and at idle I was around 15btdc so I dialed it back to 13btdc which will also hopefully drop my idle rpm back down to 1000. Plugs also looked good and the bottom of the engine remains bone dry. So after some research I believe I'm experiencing lean surging due to over advancing in vacuum. Afrs get into the 17s off throttle under vacuum and I don't recall what they were before but not in lean into the 17s. When I was losing timing due to the crank pulley walking off I was getting fireballs out the exhaust when unloading the motor or on quick on/off boost transitions like between shifts, so I dialed in more vacuum advance to counteract that. I pulled out 3 degrees of advance to start and see what that does. Other than 3 month old fuel I'm not sure where else to look next. Pulling the carbs off again would be a last resort but I guess I'll shake it down more tomorrow. Edited February 9, 2023 by Dat73z Quote Link to comment Share on other sites More sharing options...
DuffyMahoney Posted February 9, 2023 Share Posted February 9, 2023 Are you running a balance bar? How close are the throttle plates from each other? Quote Link to comment Share on other sites More sharing options...
Dat73z Posted February 9, 2023 Author Share Posted February 9, 2023 @DuffyMahoney all 6 runners are ganged together and provide the signal to the distributor, BOV, and boost controller. I'm not sure I follow your Q on the throttle plates, the spacing is set by the Mikuni Short Runner. Heres an overhead view of how I have it all laid out. Quote Link to comment Share on other sites More sharing options...
Dat73z Posted February 10, 2023 Author Share Posted February 10, 2023 (edited) So I went to fill the gas with some fresh 91 and to test the reduced timing out. Things were going great and the car was running smoother than before. On the way home I was going into boost and the ignition started cutting out. Then a crazy electrical fire started under my dash that extinguished itself. I ended up pushing the car across an 8 lane 60mph expressway during Bay Area rush hour traffic which was crazy and coasted downhill into a residential neighborhood to wait for a tow. I feel like I really can't catch a break, but I guess rewiring the car is the next step in this build. Edited February 10, 2023 by Dat73z Quote Link to comment Share on other sites More sharing options...
Dat73z Posted February 10, 2023 Author Share Posted February 10, 2023 While I was waiting for a tow my buddy told me I should wrap or paint my car blue and call it Devil Z because it's cursed, and I tend to agree. Since this turbo s30z pursuit I've had a slew of crazy ups and downs in life but I need to keep moving forward. As I was getting into boost at high speed I saw the fire and smoke billowing out from under the dash. After the tow home I inspected the area and saw that the original dash harness has melted through the factory tape loom in many areas. It seems the firewall forward is fine but everything is suspect at this point. So I think the strategy will be to start by disassembling the dash and see the full extent of the damage. Worst case a few of my buddies have fully rewired s30zs so that is an option, but watching them do it did not look like a fun process. Quote Link to comment Share on other sites More sharing options...
DuffyMahoney Posted February 10, 2023 Share Posted February 10, 2023 19 hours ago, Dat73z said: @DuffyMahoney all 6 runners are ganged together and provide the signal to the distributor, BOV, and boost controller. I'm not sure I follow your Q on the throttle plates, the spacing is set by the Mikuni Short Runner. Heres an overhead view of how I have it all laid out. How close are the throttle plates matched. With the bleed screw closed. Quote Link to comment Share on other sites More sharing options...
DuffyMahoney Posted February 10, 2023 Share Posted February 10, 2023 12 hours ago, Dat73z said: While I was waiting for a tow my buddy told me I should wrap or paint my car blue and call it Devil Z because it's cursed, and I tend to agree. Since this turbo s30z pursuit I've had a slew of crazy ups and downs in life but I need to keep moving forward. As I was getting into boost at high speed I saw the fire and smoke billowing out from under the dash. After the tow home I inspected the area and saw that the original dash harness has melted through the factory tape loom in many areas. It seems the firewall forward is fine but everything is suspect at this point. So I think the strategy will be to start by disassembling the dash and see the full extent of the damage. Worst case a few of my buddies have fully rewired s30zs so that is an option, but watching them do it did not look like a fun process. I would assume you have a single wire that is shorting to ground. Or drawing too many amps. Can you trace it? Quote Link to comment Share on other sites More sharing options...
Zetsaz Posted February 10, 2023 Share Posted February 10, 2023 Are you still running the original ammeter? There's a reason they switched to volt meters with the 280z, lots of current going through the dash harness. Quote Link to comment Share on other sites More sharing options...
Dat73z Posted February 10, 2023 Author Share Posted February 10, 2023 @DuffyMahoney no air bleeds on the OER dcoes, the throttle plates are close with the tap test but slightly imbalanced on the motor. The cammed 3.2 stroker is lumpy and gets off the line fine so the slight imbalance isn't too annoying but since I'm doing the work I may as well try and get it right. Next time I have them off I'll need to reset all of them like new butterflies and plates then test with a vacuum or something. Attached are pics from earlier in the build of the flows. @DuffyMahoney @Zetsaz my ammeter started going crazy when this was all going down but I traced one melted wire to the fuel pump circuit which I'm still using the factory wiring from the dash to the tank. I used an in tank efi walbro 255 which ramps up the pressure under boost so I guess that is one issue and maybe the original wiring couldn't take it. What's interesting is the relay subharness I made to serve that load looks perfectly fine. Another one of my buddies had the same issue a while back, where he put in an electronic fuel pump and it toasted his original harness. Another issue I see is all of the wires are loomed together so I assume a few wires going out could take out other wires they're taped up against. I think I just need to pull the interior later today or this weekend if I have time and start unlooming the harness and assess what I'm really working with as the harnesses on this car look pretty 50+ yr old original. If I can I'd like to upgrade the main power wire to take a 100+amp alternator and like @Zetsaz said just run a voltmeter and get rid of the high current wires into the cabin. Quote Link to comment Share on other sites More sharing options...
240Z Turbo Posted February 10, 2023 Share Posted February 10, 2023 The factory fuel pump wire can be used to trigger the relay, but wasn't sure if you are actually driving the pump from that wire and that caused the fire. Also, how are you retarding timing under boost? Quote Link to comment Share on other sites More sharing options...
DuffyMahoney Posted February 10, 2023 Share Posted February 10, 2023 I think you need to fiddle with those butterflies for sure. Quote Link to comment Share on other sites More sharing options...
Dat73z Posted February 11, 2023 Author Share Posted February 11, 2023 @240Z Turbo Basically I an using an oil pressure sensor to trigger a relay to provide 12v direct from the battery to the fuel pump green wire in the harness. The 12v relay harness I made is perfectly fine, but downstream from the connector the 50 year old OE wiring is all melted. @DuffyMahoney yeah, a valve adjust and pulling the carbs apart again is in order. Quote Link to comment Share on other sites More sharing options...
Dat73z Posted February 11, 2023 Author Share Posted February 11, 2023 @240Z Turbo here is the configuration. The fuse which is a 30amp didn't blow. I want to say I used 12 gauge for the subharness. Maybe the original wiring was only rated to 20 amps. Not sure, I just need a solid day for this car in particular to really dig into it but my schedule just sucks for building cars for which this is one of a few vehicle projects I have going on concurrently. Quote Link to comment Share on other sites More sharing options...
Dat73z Posted February 11, 2023 Author Share Posted February 11, 2023 (edited) @240Z Turbo apologies I missed your Q on timing. The 123 ignition has a MAP sensor. I pull roughly 1 degree of timing per psi of boost and target 20 all in at 1 bar. I can also control vacuum advance off throttle through the MAP. It was smooth all the way to 7k+ and also through the dynamic driving range before the mechanical failure (crank pulley walking off). This time I never got to redline as I was retuning for the off throttle lean surge before the electrical failure. Edit: I am also assuming the lean surge was caused by overadvancing under vacuum as pulling 3 or 5 degrees of timing resulted in AFRs dropping from 17 lean to 14 before the electrical fire. I added the timing because unknown to me the crank pulley was walking off and resulting in losing timing and shooting fire when unloading the motor. But that was the last data point I got before the car went down yesterday. Edited February 11, 2023 by Dat73z Quote Link to comment Share on other sites More sharing options...
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