harlow426@mail.com Posted January 17, 2015 Report Share Posted January 17, 2015 Dog needed to go out......having a smoke and peeking under the hood. I had noticed earlier the head had round intake ports....but didn't investigate further. Flashlight in hand I looked at the pad on block by ex. Assuming I'd see Z24......nope. Z20. I think it is original motor but too dark and rainy to look more. Which thread should I look @ to find info on z20's? Did it get a swap or did some come with z20's? 1st one Ive seen in person. Quote Link to comment
datsunaholic Posted January 17, 2015 Report Share Posted January 17, 2015 The MPG version did have a Z20, but the dataplate on the passenger side inner fender will tell you if it was originally equipped as such. Quote Link to comment
harlow426@mail.com Posted January 17, 2015 Author Report Share Posted January 17, 2015 Anyone have specs/details for the above mentioned "MPG" version? Where-do I look and what do I look for on tag on fender ? Any 'desire-able' parts on/in a Z20? Quote Link to comment
datzenmike Posted January 17, 2015 Report Share Posted January 17, 2015 The Mileage Option 720 was available from January '83-'86 and included...Z20 engine only6" rods, flattop Z20E pistons9 to 1 compression (special 45cc combustion chamber W04 casting heads)knock sensor in block and ignition retard box pass side rocker. Only on 2wd KC and regular cabs, not long beds5 speed (only)3.364 differential ratio (only)Look on engine tag. Located under pass side hood hinge on the inner fender. Looks like this... This is for a different Z24 720 but... At top It will be stamped FL720.... or KFL720 but there will be an F somewhere befor the 720 Second from bottom... Z20(S) Bottom line... FS5W71B..... HF33 (this is the 3.364 differential 2 Quote Link to comment
harlow426@mail.com Posted January 18, 2015 Author Report Share Posted January 18, 2015 The Mileage Option 720 was available from January '83-'86 and included... Z20 engine only 6" rods, flattop Z20E pistons 9 to 1 compression (special 45cc combustion chamber W04 casting heads) knock sensor in block and ignition retard box pass side rocker. Only on 2wd KC and regular cabs, not long beds 5 speed (only) 3.364 differential ratio (only) Look on engine tag. Located under pass side hood hinge on the inner fender. Looks like this... This is for a different Z24 720 but... At top It will be stamped FL720.... or KFL720 but there will be an F somewhere befor the 720 Second from bottom... Z20(S) Bottom line... FS5W71B..... HF33 (this is the 3.364 differential It is amazing how fast ya-all get the info posted....with pics-accurate specs-etc!!! THANKS!!!! Ratsun kicks-ass!! 1 Quote Link to comment
harlow426@mail.com Posted January 18, 2015 Author Report Share Posted January 18, 2015 Picked up a 92% perfect factory service manual today (84-720) an St-Vinnies for a whopping $5.oo. Has specs for the Z2.0 so I can answer my own ??'s now!! Also a factory 78 B210 service manual(81% perfect) for $4.00. Anybody need the b210manual or a 82 810-max service manual??? 1 Quote Link to comment
harlow426@mail.com Posted January 18, 2015 Author Report Share Posted January 18, 2015 Well mystery solved....there is the fender tag. thought pic was attached but fighting photobucket. tag says Z20 and has the f 1 Quote Link to comment
datzenmike Posted January 18, 2015 Report Share Posted January 18, 2015 This was a crazy attempt by Nissan to make a fleet truck, possibly for federal or rental use, that had attractive mileage features. (I still don't know what the mileage was) Small 2 liter displacement, insanely low 3.364 differential but with super low wide ratio trans so you could get it rolling from a stop, no automatic, 9 to 1 compression to increase thermal efficiency and naturally a knock sensor and spark retard because this thing is going to ping like hell with all the aforementioned features. Did I mention it also came with a 240mm clutch and pressure plate because you ARE going to have to slip the clutch to get a heavy 720 rolling. If you ever scrap the engine the 152.5mm rods are sought after for making high revving LZ hybrid engines 2 Quote Link to comment
harlow426@mail.com Posted January 18, 2015 Author Report Share Posted January 18, 2015 This was a crazy attempt by Nissan to make a fleet truck, possibly for federal or rental use, that had attractive mileage features. (I still don't know what the mileage was) Small 2 liter displacement, insanely low 3.364 differential but with super low wide ratio trans so you could get it rolling from a stop, no automatic, 9 to 1 compression to increase thermal efficiency and naturally a knock sensor and spark retard because this thing is going to ping like hell with all the aforementioned features. Did I mention it also came with a 240mm clutch and pressure plate because you ARE going to have to slip the clutch to get a heavy 720 rolling. If you ever scrap the engine the 152.5mm rods are sought after for making high revving LZ hybrid engines Going to try and do good repair....but good to know about rods. THANKS :thumbup: Removing rear bumper and putting on hard tonnnn-o cover.....this truck has been granted immunity from "hauling" towing/severe duty. Stereo probably add 200lbs when done but truck is going 2 B treated nice and driven' on Sundays. I'll give ##'s for mpg after she is rollin' in a proper state of tune. Partin' 83 flatbed....should I save diff? 1 Quote Link to comment
datzenmike Posted January 18, 2015 Report Share Posted January 18, 2015 Partin' 83 flatbed....should I save diff? What ratio does the engine tag say? 3.545?? 1 Quote Link to comment
harlow426@mail.com Posted January 19, 2015 Author Report Share Posted January 19, 2015 What ratio does the engine tag say? 3.545?? THAT IS A BIG 10-4 GOOD BUDDY. This was a crazy attempt by Nissan to make a fleet truck, possibly for federal or rental use, that had attractive mileage features. (I still don't know what the mileage was) Small 2 liter displacement, insanely low 3.364 differential but with super low wide ratio trans so you could get it rolling from a stop, no automatic, 9 to 1 compression to increase thermal efficiency and naturally a knock sensor and spark retard because this thing is going to ping like hell with all the aforementioned features. Did I mention it also came with a 240mm clutch and pressure plate because you ARE going to have to slip the clutch to get a heavy 720 rolling. If you ever scrap the engine the 152.5mm rods are sought after for making high revving LZ hybrid engines Like the idea of a knock sensor..........heavy(over) loaded/trailer under hard accel or pushing a headwind @ high speeds I have noticed detonation.I am aware of the conditions causing it and adjust accordingly but I like the idea of being able to flog it & it retard the ignition 4 me. I have some hardware sitting here...I had contemplated an cable actuated ign timing adj for the dist base already to solve the problem. 3.3 gear ratio 'higher' than 3.5......lower gear ratio=LARGER number or.....the smaller the # the 'taller' the gear ratio Are the gear ratios different in the trans verses std 720 5speeds. I have had several and know all the shift points, no glitch up/downshifts w/o touching clutch......I think if it was different it would mess with my head. 1 Quote Link to comment
wayno Posted January 19, 2015 Report Share Posted January 19, 2015 The smaller the number, the lower your RPMs will be on the hiway at a given speed. 2 Quote Link to comment
harlow426@mail.com Posted January 19, 2015 Author Report Share Posted January 19, 2015 The smaller the number, the lower your RPMs will be on the hiway at a given speed. Yes. 1 Quote Link to comment
datzenmike Posted January 20, 2015 Report Share Posted January 20, 2015 I don't know how the ignition is retarded but the output from the detonation control unit goes directly to the distributor module. The 280zx has a special ignition retard built into the matchbox and if use on a regular matchbox dizzy it will retard up to 10 degrees when revved up so maybe the 720 does the same. It's the knock sensor's job to prevent the retard when plugged in and when knocking is sensed it allows it. According to the FSM when checking the timing it will retard 10 degrees when revved above 2,000 RPMs WHEN the knock sensor is unplugged. I just checked and the Z20 module is a different part from the usual Z24 module. This would make a great turbo retard based on a knock sensor. 1 Quote Link to comment
harlow426@mail.com Posted January 23, 2015 Author Report Share Posted January 23, 2015 This was a crazy attempt by Nissan to make a fleet truck, possibly for federal or rental use, that had attractive mileage features. (I still don't know what the mileage was) Small 2 liter displacement, insanely low 3.364 differential but with super low wide ratio trans so you could get it rolling from a stop, no automatic, 9 to 1 compression to increase thermal efficiency and naturally a knock sensor and spark retard because this thing is going to ping like hell with all the aforementioned features. Did I mention it also came with a 240mm clutch and pressure plate because you ARE going to have to slip the clutch to get a heavy 720 rolling. Is the trans different from the standard 720 5 speed? MIKE? Quote Link to comment
datzenmike Posted January 23, 2015 Report Share Posted January 23, 2015 There were two different ratio set used on the 720. A mid ratio with a 3.321 first for use on trucks with larger displacement and low differential gears like 4.11 and 4.375. A wide ratio with a low geared 3.592 first and big jumps in RPM between shifts but easy take offs. This would be good for heavy 4x4s, underpowered diesels and ones with very high differential ratios such as 3.364 and 3.545... this is what will be in the Milege Option Z20 powered truck. 1 Quote Link to comment
harlow426@mail.com Posted January 23, 2015 Author Report Share Posted January 23, 2015 There were two different ratio set used on the 720. A mid ratio with a 3.321 first for use on trucks with larger displacement and low differential gears like 4.11 and 4.375. A wide ratio with a low geared 3.592 first and big jumps in RPM between shifts but easy take offs. This would be good for heavy 4x4s, underpowered diesels and ones with very high differential ratios such as 3.364 and 3.545... this is what will be in the Milege Option Z20 powered truck. Ok....so trans in the 83 with the Z20/3.3 rear-end would b the same as the trans in most 720's(2wd...no 4wd's)?? I have had 80-86 720p/u's and all the 5 speeds seemed the same. #'s and location on trans for id? THANKS!! Quote Link to comment
datzenmike Posted January 23, 2015 Report Share Posted January 23, 2015 No... There were two different ratio set used on the 720. A mid ratio with a 3.321 first for use on trucks with larger displacement and low differential gears like 4.11 and 4.375. A wide ratio with a low geared 3.592 first and big jumps in RPM between shifts but easy take offs. This would be good for heavy 4x4s, underpowered diesels and ones with very high differential ratios such as 3.364 and 3.545... this is what will be in the Mileage Option Z20 powered truck. Small displacement (L20B Z20) 2wd will have them, 4x4s, and diesels. Quote Link to comment
harlow426@mail.com Posted January 23, 2015 Author Report Share Posted January 23, 2015 Trans id#'s for the two options? So you are saying the 5speed in the mpg truck is different than the std 5speed? Fender tag #'s for the 2 options? Different than the 5 speed in my 80kc with l20b? Quote Link to comment
datzenmike Posted January 23, 2015 Report Share Posted January 23, 2015 No way to tell which one from engine tag or looking at it. Read my post, already answered... No... Small displacement (L20B Z20) 2wd will have them, 4x4s, and diesels. Naturally the 4x4 won't be any use to you because the speedo is run off the trans case. The diesel and the L20B transmission will have the wrong front case for a Z series engine but it can be swapped. If the teransmission is out on the ground or otherwise accessible, mark the input and output splines in the 12 o'closk position, place in first gear. Have someone count the output turns while you turn the input exactly 20 times. If the output turns are 5.5 you have a 280zx 5 speed If 6 turns you have a 3.321 mid ratio first gear, the most common car and truck 5 speed. If it turns 6.5 turns then you have the wide ratio (3.592 first gear) transmission. Quote Link to comment
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