Neubs

Following on from the SB needle install I decided to adjust the float level to factory. Previously I had the float level a little higher as a band aid fix to richen the top end mixture of the SM needles. The rear float bowl gave me grief. I think I had the lid off 20 times before the geometry of the float was massaged so it wouldn’t stick in the bowl not closing the jet properly. I got there in the end. When you bending little metal tabs minute amounts you need a good swag of patience. Using the float sync tool and a trusty bit of clear pine dressed down to 9/16” thick the floats are set to the same level. The Nissan workshop manual suggests making one float higher than the other, presumably for G forces under acceleration, but I’ve never done this. Working on the 240Z is not the highest priority in my life (although I wish it could be!) so road testing and datalogging with the Innovate LM2 wideband will have to wait. Video below. https://youtu.be/0bSywC4ydUI

I turned my attention to optimising the needles in the Hitachi SUs. I took the functional stations from the SM, RV and RU needles I’ve trialed previously and went searching for a best match. I went to use the Mintylamb.co.uk resource but found that had closed down some time ago. Ended up using Teglerizer’s resource http://www.teglerizer.com/suneedledb/ to find SB needles were the closest. Ended up sticking the needles in without lowering the fuel floats down from the band aid fix to riches top end with the SM needles. The SB needles worked a treat and the AFRs are offset by the amount that raising the float changed. Overall very happy. Next port of call is to lower the floats to factory and I reckon I will have 99% convergence to the best mixture I can achieve without making custom needles. Fingers crossed that’ll work!

Fast forward to the present for this post. Progress is being made to optimise the stroker motor with the round top SUs for a goal of 200hp at the wheels. I recycled a piece of the old aluminised steel exhaust when the Zstory race sport header and JDM muffler (looks like a 432 muffler) was installed back in late 2016 to try and save a few bucks but have regretted it since. That was removed over the weekend and a Zstory connecting centre pipe put in its place. So now the exhuast system is a full stainless steel system from Zstory and I’m stoked. It looks and sounds exactly how I want my 240Z to sound! A question for the round top experts. Has anyone modified Hitachis round tops to a David Vizard ‘specification’? I had a comment on the YouTube channel recommneding his work on SUs. I can find at least one workshop that prepares ‘David Vizard’ SUs for Minis with some photos of the modifications. I’m keen to investigate further and apply some of the modifications as a backup if I cannot get 200hp at the wheels with the round tops in standard trim just I’m not sure if modifications meant for SUs will be as effective on the Hitachis.

I’m going to treat this like a steak and vege dinner and drive right into what I think is the steak. Mechanicals are my steak and all else is my vege.... Crank and pistons. The motor is a stroker motor using an LD28 V07 crank. I actually had the crank a few years before I acquired the 240Z. I paid a handsome some of $150NZD for the crank and $350NZD shipping to Australia back in 2007. I think these days good V07s cost significatly more? I had the rods, crank, pistons, flywheel and Ross harmonic balancer balanced to an inch of their life. The crank was also knifeedged and nitrided and as a bonus was straight as a die beforehand. I think about 3 kg was cut from the crank. It might be excessive for a motor that doesn’t rev past 6.5k RPM (due to camshaft selection) but in my mind balancing is cheap insurance for your motor. Pistons were .02” oversized Mistubishi 4G64 8v SOHC pistons decked about 2.00mm for a zero deck height at TDC. This give 2960cc. I did not use forged as I think eutectic material is sufficient (i’m not looking to make 100hp/l), not to mention lighter and reduce thermal coefficient of thermal expansion in comparison to forged material. I have a few videos on the bottom end on my YouTube channel referenced in the parent post. I’d like to write more but my lunch break is finite. Thanks for reading.

I think I better start firstly with a quick intro. Hello from the Wide Bay area of sunny Queensland in Australia. I’m a long time ‘guest’ lurker to the HybridZ forums mainly for research and ideas particularly when it comes to round top Hitachi SUs. I’ve loved Z cars since I first laid eyes on one in my early teens when I went to a historic race meeting at a local track with a friend’s family (who also have an affiliation with Datsun 1600/510). There was no escaping the ensuing obsession. This was only made worse by the inception of the Fast and Furious franchise coincidently at the same time I acquired my learners driver licence. I am shamed to say I have had at least one car with “cool” under body neons…. On to the car! This particular car is a 1971 chassis number #629 purchased in 2009. The car was a daily driver retaining the L24 and had a 280ZX gearbox and ignition. I believe it was Victorian sold in a blue colour and was repainted to red in the late 80s or early 90s (judging by the Australian fashion sense in the photos). I have maintained continuous registration of the car as well. The car has had various levels of priority around my life choices and events. I think I put less than 1000 miles on it between 2010 and 2017, is this considered Datsun abuse? I am now at a stage where I can tinker with it more and crack on with a long time goal to leave a legacy of my experiences and information on YouTube and lessor so on Instagram. One immediate goal is to try for 200WHP with only optimisations to fuel, ignition and exhaust. There are gaps to the story thus far which I intend to fill in with further posts. I want to keep this post short and sweet. Cheers, Neubs PS. The current specs are: ENGINE (currently making 170WHP) - Overbored and stroked to 2996cc - Approx. 10-10.5:1 compression ratio - L28 F54 block - L28 N42 head, 1.0mm O/S Ferrea Super Flo valves and match ported - ‘V07’ LD28 crank, balanced, knife edge and nitrided surface - L24 connecting rods - Modified Mistubishi pistons - Crow Cam camshaft; - 292° duration 0.495” valve lift intake - 296° duration 0.510” valve lift exhaust - Innovate Motorsports LM-2 datalogger and wide band O2 sensor COOLING - Ebay 75mm alloy radiator - 2 thermo fans - 280ZX thermostat with Tridon temp switch IGNITION - Pertronix Ignitor I module - MSD 6A ignition - L24 distributor with ‘7.5 plate’ and vac advance FUEL DELIVERY - Rebuilt round top 240Z Hitachi SU carbs with ZTherapy rebuild kit - SM needles with higher set fuel float level - Holly Red fuel pump EXHAUST - ZStory stainless steel Race/Sport headers - ZStory stainless steel Z432 style JDM muffler - Recycled mild steel centre pipe and generic hotdog muffler TRANSMISSION - 71C RB20DET gearbox - Exedy ceramic clutch and pressure plate DIFFERENTIAL - Standard rebuilt open centre 3.9:1 R180 - Standard uni joint drive shafts BODY - Restored Japan polyurethane front bar INTERIOR - Stock (and very worn out) - 280ZX modified tacho SUSPENSION - Stock springs - Stock brakes - Stock geometry components - Koni adjustable shock absorbers ROLLING STOCK - Rota RB-R