Ole Blue Posted October 15, 2015 Report Share Posted October 15, 2015 New to the forum but not new to Datsun's. Had a 510 since I was 12. Owned 3 510's, two 720's and a sentra here and there. Just picked up a 85 720 with a blown Z24 for my son. Not sure what happened, we'll know as soon as we crack it open. My question to the forum is what are my options out there for a torquey motor for this truck that doesn't use the z head and bolts up to the 5 sp already in there? KA maybe? z24 block with a L-series head? It's a two wheel drive LB King Cab 5 sp. What say you all?? My son will use this as a daily driver (40 miles a day) but we're looking for a good torquey option that will be reliable to haul and tow here and there. Thanks!! Considering all options. Let's hear it. 1 Quote Link to comment
Rhino13 Posted October 15, 2015 Report Share Posted October 15, 2015 Well if you want reliable, a ka would be a better option than the LZ hybrid because of the fuel injection. An L head will bolt to the z24 block, but you need to modify the timing cover and make your own gasket. A ka will also bolt right up to the 720 trans, you'll just have to deal with wiring, or convert it to run a carb. 1 Quote Link to comment
datzenmike Posted October 15, 2015 Report Share Posted October 15, 2015 Likely a blown head gasket, a common thing on Z24 when they reach 100K. Fix it for under $50 and run with it. Nothing wrong with the Z 24, it makes 130 torque at 2800 a real stump puller for a heavy 720. An L head will fit but you would also need the manifolds which when installed on a left leaning Z series engine will be tilted down towards the steering column.... might fit but carb won't be level at all. The fix is to replace the Z series transmission with a matching L series and get L series engine brackets that will allow the engine to be tilted over to the right in the L series position. Timing cover needs to be from an L20B and 2 cm taller with the timing chain lengthened to fit. Compression would be 10 to one.... a bit high. 1 Quote Link to comment
Ole Blue Posted October 15, 2015 Author Report Share Posted October 15, 2015 Here's a pix. We'll keep you guys in the loop. [/url]">http://http://s1103.photobucket.com/user/volz4/media/Builds/12115839_751486611647418_4411853238046623294_n_zpshiwv9nxh.jpg.html'> 1 Quote Link to comment
bananahamuck Posted October 16, 2015 Report Share Posted October 16, 2015 Do you hate NapZ ? Or just don't know where parts are?? Emerys auto wrecking ,, over by Aberdeen auto wreckers had a few Napz 24s that turned over by hand in trucks out back. and a pretty nice head in the counter area, when we were there 6 months or so ago .. I assume that kinda thing doesn't sell real fast,, maybe i'm wrong. Bill out in Elma might be able to put you something together for a reasonable price,, if your block is still good and just hate Napz head on it. Quote Link to comment
Ole Blue Posted October 16, 2015 Author Report Share Posted October 16, 2015 Don't hate the head, just never liked the twin plug design. Bill and I go way back. We've already talked about options. I've rebuilt a few, just wanted to try something different this time. 1 Quote Link to comment
Ole Blue Posted October 18, 2015 Author Report Share Posted October 18, 2015 What do you guys think about a KA24 with a turbo on it? What year and out of what can I find the best fit for this truck? 240SX? How much trouble is the swap? Just keeping my options open. Pulled the motor today. Teardown starting this week. Quote Link to comment
Lockleaf Posted October 18, 2015 Report Share Posted October 18, 2015 240sx fuel injection is the easiest to use. The engine bay harness is separate from the rest of the car harness and its multi point fuel injection. Truck stuff is built into one large harness and is throttle body until the very late 90s. 240 is front sump, truck is rear. Truck pan will not fit 240sx block because 240sx has a girdle on the main caps. Best bet is likely 240sx intake manifold and fuel system, wiring and ecu attached to a truck block. 1 Quote Link to comment
Ole Blue Posted October 19, 2015 Author Report Share Posted October 19, 2015 Late night... Time to crack her open and see what happened. Quote Link to comment
Ole Blue Posted October 19, 2015 Author Report Share Posted October 19, 2015 This truck seems to sit a bit high in the rear. Any idea why? Quote Link to comment
Lockleaf Posted October 19, 2015 Report Share Posted October 19, 2015 Likely the torsion bars up front have gotten a little slack. Tighten them up and level the truck if you want, but the 2wd had a rake from the factory I believe. 1 Quote Link to comment
Rhino13 Posted October 20, 2015 Report Share Posted October 20, 2015 Because there's no blocks! Haha 1 Quote Link to comment
Ole Blue Posted October 27, 2015 Author Report Share Posted October 27, 2015 Verdict on the motor.Two spun rod bearings. Quote Link to comment
datzenmike Posted October 28, 2015 Report Share Posted October 28, 2015 All 521/620/720 trucks have a slight 'rake'. This allows a load to settle the truck and the NLSV will adjust the brake bias properly. If you don't carry a load regularly then level it to suit your taste. Quote Link to comment
tommy Nadon Posted August 20, 2021 Report Share Posted August 20, 2021 Hey there, did you ever come up with an easy engine swap for your 720? I have an 84 that runs great, but boat ton of miles. Should I just rebuild? 1 Quote Link to comment
datzenmike Posted August 21, 2021 Report Share Posted August 21, 2021 Mileage is not the defining reason for rebuilding it. You say it runs great, if so why rebuild? 2 Quote Link to comment
Charlie69 Posted August 21, 2021 Report Share Posted August 21, 2021 4 hours ago, tommy Nadon said: Hey there, did you ever come up with an easy engine swap for your 720? I have an 84 that runs great, but boat ton of miles. Should I just rebuild? How do you know a previous owner did not already rebuild it? 1 Quote Link to comment
tommy Nadon Posted December 4, 2021 Report Share Posted December 4, 2021 Hey thanks for responses. The motor has 260,000 and is just plain tired. 1 Quote Link to comment
tommy Nadon Posted December 4, 2021 Report Share Posted December 4, 2021 How can I upload photos to show you guys my build? 1 Quote Link to comment
datzenmike Posted December 4, 2021 Report Share Posted December 4, 2021 260,000. When I grew up cars were hard pressed to get to 100,000 before they needed a rebuild. 2 Quote Link to comment
Stoffregen Motorsports Posted December 4, 2021 Report Share Posted December 4, 2021 My wife's 2006 Scion xB commuter has 375,000 miles and it's still got the original clutch. One alternator change, two transmission changes, one water pump and a shit ton of brakes, but the motor is still going strong. 100,000 miles on an old Datsun motor is a bit long in the tooth, and 280,000.... that thing is probably worn to the nub. 1 Quote Link to comment
datzenmike Posted December 4, 2021 Report Share Posted December 4, 2021 Oil is much better today than it was prior to the '70. In '62 the PCV valve was put in cars and this extended the oil life by about twice. By the mid '50s most all engines had oil pumps. My dad's '51 Chev was splash oiling. With an oil pump you can start using a detergent oil that holds contaminants in suspension so an oil filter can sift it out. Before the PCV valve and detergent oils it was common to take the valve cover off like a jelly mold. Rocker arms were hidden under a thick layer of gunk. I used to do oil changes on dad Chev but could only get 3 of the 4 quarts into it. My neighbor helped my dad replace the babbitt faced bearings and there was an inch of white putty like crap in the bottom of the pan. Like I say if you got over 80k you were doing very well. 2 Quote Link to comment
Charlie69 Posted December 6, 2021 Report Share Posted December 6, 2021 My 86 720 daily driver just rolled 470,000 runs strong but has rough idle. My 84 has 134,000 miles with a blown head gasket. I have a rebuilt Z20 and just picked up an 85 720 automatic for it. I hope to get this truck on the road before May as I want to sell my 86 and keep the 84 ST. Not sure how the Z20 and the automatic will work but if I do not like it there is always a KA or VG option. 1 Quote Link to comment
datzenmike Posted December 6, 2021 Report Share Posted December 6, 2021 The '85 will have a locking torque converter and will work very well with the Z20. What differential? I would suggest a 4.11 for a heavy truck. Don't forget the Z24 is a torque monster the 2.0 is not. You'll need an automatic radiator for the cooler or get an add on RV cooler. Quote Link to comment
Stoffregen Motorsports Posted December 6, 2021 Report Share Posted December 6, 2021 7 hours ago, Charlie69 said: My 86 720 daily driver just rolled 470,000 runs strong but has rough idle. Holy shit. Quote Link to comment
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