Jason Gray's Electronic Distributor Writeup
OK, here's how the '78 remote igniter box is connected. The Green and Red wires connect to the distributor. The Black /White wire goes to the positive + side of the coil and also the ignition switch and is hot on start and run. The Blue goes to the negative - side of the coil and to the tach in the dash if you have one. Black goes to chassis ground.
Installing a Nissan factory Electronic Ignition distributer (EI Dizzy) in place of the old breaker points dizzy is one of the most recommended simple modifications that can be made to any L series powered 510 still running breaker points. You get better reliability, more accurate timing and a more powerfull spark that delivers easier starting, smoother idleing, eliminates missing at cruise and the EI dizzy does not need "tuneup" every few thousand miles like the old point/condensor dizzy. Considering that these dizzys can pull a 6 cylinder L28 to the 6500RPM redline, the electronic trigger mechanism should be capable of providing hot spark for a 4 cylinder to at least 10,000 RPM, the only real limitiation here is the slop in the drive spindle/gears effecting timing accuracy at high RPM.
You could get an aftermarket EI conversion kit such as the "Pertronix" and convert a single breaker point dizzy to a magnetic trigger. See http://www.vintageperformance.com/retrorockets/Datsun/nissan.htm. One limitiation of the 510 points dizzy is the small size of the stock distributer cap. With hotter spark, there is more of a chance of cross firing between terminals and fortunatly the later EI dizzy uses a larger size cap to space the plug terminals further apart. This is important because any dirt or moisture in the cap can lead to spark arcing along the surface of the cap, firing the wrong spark plug. As cylinder pressure (and performance) increases, it takes more voltage to make the spark jump at the sparkplug under compression. The spark will seek the path of least resistance, this may be a path that jumps to the adjacent cap ternimal and to a plug not under compression! A better option if you do decide to use a pertronix kit is to install it into a single breaker points dizzy from an early L20B as these use the larger diameter cap. Also note that the pertronix kit will not work on a dual points dizzy, as used on '70-'73 L16. Dime Quarterly article in vol2 issue4 covers instalation of pertronix ignitor.
There were 2 different versions of nissan factory EI dizzys available. Some of the L20B engines (particularly in California) from '75 to '78 vehicles had a EI dizzy that is triggered when the 4 pronged rotor wheel spins past a single fixed magnetic sensor unit. The early EI dizzy used a large ignitor box to process the dizzy trigger signal and spark the coil. The ignitor box is remotly located from the dizzy. The ignitor box is inside the car buried somewhere behind passenger side dashboard/kickpanel. The remote ignitor dizzys look much like the dizzy from the 280Z if you are in junkyard hunting and want something for reference, both use similar trigger mechanism. I dont have any experience installing the single pickup dizzy. The extra hassle of getting and installing the ignitor box and wiring remote from the dizzy makes these more work to retrofit onto a 510. If you need a wireing diagram to hook up the remote ignitor box, check here.
Above picture is of the early style '75-'78 EI dizzy . Note how the magnetic pickup trigger only gets signal from 1 lobe of the 4 lobed spindle rotor each time it fires, possibly less accurate than the later 4-prong trigger. The necessary ignitor box to make this early style dizzy function is located remote from the dizzy. Photo courtesy of Scott Christopher.
The EI dizzy I suggest using is the later type with a "matchbox" ignitor with improved trigger mechanism and electronics. Instead of the large remote located ignitor box, the transistorized ignitor is a black plastic matchbox sized module that is bolted directly on the outside of dizzy body. In place of mechanical breaker points, the ignition module "matchbox" and the magnetic trigger mechanism function to electronicly spark the ignition coil. The electronics automaticly provide the optimum coil saturation (equivalent to dwell with breaker points). The improved trigger of the matchbox ignitor dizzy consist of a fixed magnetic wheel with 4 inward pointing prongs. Attached to the dizzy rotor shaft is a 4 pronged star wheel. Every time the 4 prongs of the rotor star align with the 4 prongs of the fixed trigger a slight magnetic pulse is created and produces an electric current pulse in the thin coil of wire on a spool below the trigger. The ignitor senses the current in the spool and transistorized circuitry causes the ignition spark by momentarily disrupting the ground path of the ignition coil. With no parts in rubbing contact (like the old breaker points) there is no mechanical wear of the trigger mechanism. The shaft bearings of a used EI dizzy are likely10 years newer than your 510 points dizzy and the EI dizzy bearings have not had to contend with the extra drag and vibration of the breaker points so should last much longer before developing slop.
Above pictures show the later "matchbox ignitor" style EI dizzy. The "matchbox" ignitor is clearly visible on side of dizzy.
The desireable "matchbox" ignitor dizzy came fitted on L20B engines from '79 200sx, and HL510 cars and '79-'80 620 pickup truck. The same design of dizzy was also used on fedral emmisions equiped 4 spark plug cylinder head '80 and '81 NAPS-Z20 "S" (HL510) and NAPS-Z20"E" (200sx) and possibly the '81 NAPS-Z22 "S" pickup motor. The NAPS-Z engines starting in '82 use a different cylinder head with 8 spark plugs, two spark plugs per cylinder (like earlier California market heads). The dizzy from 8 plug head engines will not swap to a L series engine, the only NAPS-Z dizzy that will work is from the 4 plug head engines. In my experience of junkyard hunting, you are more likely to find a '80-'81 NAPS-Z HL510 or 200sx than the '79-'80 L20B vehicles. The 280zx L28, Maxima L24E, and some 210 "A" series motors also used the same style of desireable dizzy. The 280zx/maxima dizzy body could be used if you change out the 6 pronged trigger wheel/star with a 4 pronged trigger wheel/star. The "A" series motors use a drive gear (instead of spindle with tang) so wont work with a L series. However, it is possible to change out the drive gear from "A" series motor dizzy to the correct drive tang for the L series. Just drive out the roll pin on the drive shaft (outside of the dizzy body) to swap the shaft. Alternatly, the "A" series does have a 4 pronged trigger wheel and rotor star needed to modify a 280zx/maxima dizzy into a 4 cylinder unit.
Ive found that there are two configurations of dizzy housings. The most common locates the ignition module foreward of the dizzy (away from exhaust manifold heat-good). The other (early?) type locates the module on the rear side of the dizzy, facing toward the hot exhaust manifold, probably not the best configuration for longevity of the ignition module. The body casting of the two types hold the distributer cap oriented 45 degrees differently. To compensate, the star trigger wheel has the alignment tab oriented 45 deg different so the spark rotor is pointing at a cap terminal when fireing. The distributer cap and rotor are the same configuration for both housing types. Keep the orientation type of star and body together, dont intermix the rotor star with alternate configuaration of body or your spark will fire while the rotor is pointing directly between two plug wire terminals and will crossfire. It is not possible to rotate the rearward facing ignitor body style dizzy so the ignitior faces foreward because the vacuum canister interferes with the thermostat housing. If you have a rearward facing module dizzy, wrap the section of #1 exhaust manifold with header insulation tape to reduce heat to the module. (or fabricate a small heat shield for the dizzy?). One other non-compatale item, the spark rotor from a 280zx is too tall to fit in the 4 cylinder distributer cap. I mistakenly hasseled an autoparts store employee by insisting that he sold me the wrong distributer cap since the cap was "too short" and hit the rotor. Problem was that I was using a non-compatable 280zx spark rotor. Otherwize, feel free to mix and match parts from different dizzys as needed to build one with the correct trigger, drive tang and best advance mechanism for a 4 cylinder L series, the parts from these dizzys are usualy interchangeable.
The EI dizzy from a L20B is a direct bolt on for any other L series 4 cylinder engine, just be sure to get and use the thin steel "L" shaped adjuster plate and aluminum dizzy pedistal from the donor engine. The only drawback to the 4 plug NAPS-Z dizzy is that it is not configured to directly bolt up to the L series timing chain cover. The actual body of the NAPS-Z dizzy is identical to the '79-'80 L20B EI dizzy, the difference is that the aluminum dizzy pedistal that bolts to the NAPS-Z timing chain cover wont fit a L series timing cover and the matching "L" shaped steel timing adjustment plate is different. To bolt a NAPS-Z dizzy onto a L series motor, use the aluminum pedistal from another a L series EI dizzy. Just get the aluminum stand and steel adjuster plate from a 280zx, maxima or L20B motor and use it. You can also use your stock L16 aluminum stand and modify the NAPS-Z adjuster plate to fit. This requires flipping over the steel "L" shaped adjuster plate and moving/enlarging the adjustment slot to fit the new dizzy and stand. If you need to modify the "L"plate, just make sure that with the dizzy on the motor and crankshaft around #1 cylinder at 10deg BTDC (check that both camshaft lobes are pointed upward to verify #1 cylinder is on compression stroke), you should be able to adjust the dizzy so the triggers star/wheel prongs align up and fire the coil. If you need to reposition the range of dizzy adjsutment at the adjsuter bolt between the "L" plate and pedistal, you can remove the oil pump, pull out the drive spindle and re-install spindle positioned on a different crank gear tooth. Figure out wich cap termianl the rotor is pointing at when #1 cylinder is firing and route the plug wire to that cap terminal. Then route the rest of the plug wires, rotor turns CCV viewed from above and the fireing order is 1-3-4-2. Even when used with matching pedistal and adjsuter plate, some EI dizzy comes setup with the upper rotor oriented 180 degrees different from the drive tang (as compaired to the stock 510 points dizzy, so the cap teminal closest to the radiator is now #3 instead of #1 cylinder). Check and verify where the rotor is pointing, you mayl need to swap the spark plug wires 180degrees on the cap so the spark goes to the correct cylinder. Alternatly, to retain your "stock 510" plug wire routing, you can dissasemble the dizzy to remove the upper mechanical advance rotor, turn upper rotor180 degrees on the mechanical advance weight pins. (so the advance weight pins fit on the opposite rotor slots).
The electrical connections are really simple when you have the dizzy with black matchbox sized tranzistorized ignition module. There is a "T" shaped connection formed from two plug terminals labeled "B" and "C". For the "B" terminal connection (verticle leg of the "T" shaped connector), use crimper end connections to make a new jumper wire that goes from the "B" matchbox terminal to the + terminal of igniton coil. This jumper wire supplies the matchbox ignitor with ignition key switched + current. The "C" terminal, the horizontal top terminal of the "T" shaped matchbox connector gets wired directly to the - ignition coil terminal. This is the grond path for the ignition coil, ground connection intermitantly disrupted by the matchbox ignitor to fire the coil. Rather than using the stock electrical harness breaker points wiring for the matchbox "C" terminal to -coil terminal, I strongly suggest splicing in a new jumper wire directly berween -coil terminal and "C" terminal. I encountered coil failure that I traced to a short to ground in the stock harness when I was using the stock breaker points ground wire. Possibly the increased voltage of the EI system overloaded the stock harness wire?? Simply bypassing the stock breaker points wire(s) with a single new ground wire also simplifies conversion from a dual points dizzy if you are still running it. Use the "T" terminal+wires from the donor car to make a nice plug together terminal connection at the matchbox. Sometimes there is also another ground terminal that screws into the body of the dizzy but I have found this ground is non-essential, dont worry if it is missing.
In order to get the full benefit of hotter spark with the EI dizzy, you should remove the ballast resistor from the ignition coil circiut. The ballast was there so that only 6-8 volts of current went to the coil windings to reduce energy of the igniton system and lessen breaker points pitting. Removing the ballast resistor will supply the coil with constant 12-14 volts for hotter spark all the time, not just while the starter is cranking. You should use a coil that was designed for EI as it will give a stronger spark and because using the old breaker points coil with EI may cause the old coil to overheat. Get the coil from the EI dizzy donor car or get a EI specific aftermarket coil such as the MSD Blaster 2 coil. Do not use a coil with internal ballast resistor such as the Bosch blue coil. (Popular with air cooled VW crowd). To finish off your high output ignition, use plug wires with spiral wound metal core (spiral windings supress radiio noise). Do not use stock type carbon core wires that use high wire resistance for radio noise suppresion and are prone to burning out. I have run my EI dizzy without ballast on both types of factory tachometers (parallel and serial) and the tach works fine and has suffered no damage from the increased voltage. Factory spec for EI spark plug gap is .041" so open up your plugs to take advantage of the stronger spark.
The transistorized ignitor matchbox is very reliable. (Much more so than breaker points!) I have not experienced a failure with my junkyard harvested unit in over 70,000 miles of additional use. I have heard of sudden failures however so carrying a spare ignitor is not a bad idea. New from Nissan, the ignitor module alone cost over $150 so try to keep a junkyard spare on hand. A cheap fix for a dead or missing module is to use a Chevy HEI module from a '77 Corvette (about $15 new), There are a bunch of websites with the HEI module instalation directions, take your pick from: Dime Quarterly, ugly datsun webpage , or Kyle's Ztech.The HEI module is also usefull if you get one of the early "remote ignitor box" single pickup type dizzy but dont have the ignitor box.
I once tried using a ignitor module from a '83 280zx. This had not one "T" shaped terninal but two"T" terninals (4 external wires connected). The extra set of terminals is there to somehow tie in with the EFI brain. When i tried using the 280zx module, I found that it produced approximately 20 degrees of RPM dependant timing retard. The more the motor reved, the closer to 0 TDC the timing light marks moved, opposite of the mechanical advance mechanism! Nothing faulty with the mechanical or vacuum advance mechanism, the retard was coming from the ignition module. Ive since learned that these were used on '81 to '83 280zx and maxima motors.This module should not be used on a 510 (since it has no EFI brain). Make shure your module only has one of the "T" terminals. The 280zx ignitor controlled timing retard might make a interesting boost retard mechanism for a turbocharged engine if a way of controlling the retard could be linked to the boost level?
You should dissasemble your dizzy to check the condition of the mechanical parts. If the dizzy has never been dissasebled then some of the screw may be frozen in place, use a good screwdriver and avoid stripping out the screw head slots. To remove the breaker plate assembly, you first need to remove the trigger star wheel and the vacuum advance arm. To remove the trigger star from the rotor shaft, remove the plastic spark rotor and then use two flatblade screwdrivers to simultaniously pry upward on opposite sides of trigger wheel. Remove the vacuum advance canister before removing the breaker plate assembly. The screw that attaches the vacuum canister actuating rod only threads into the moveable advance plate, the special screw has a unthreaded end just sticks into the hole of the actuating rod. When reassembling a dizzy, use small needle nose pliers or magnetic phillips head screwdriver to install the special actuating rod screw, the rod must be held in place while the screw is threaded in to the advance plate so the unthreaded portion engauges the actuating rod hole. Only after the actuating rod is attached can you screw the vacuum canister to the dizzy body. To fiddle with the mechanical advance parts, you need to remove the upper portion of the rotor shaft (see photo below). To remove the shaft, pry out the rubber plug at the end of the shaft hiding the retaing screw. Remove the retaining screw and the upper portion of the shaft should easily slip off. I have encountered upper shafts that were corroded to the lower shaft. If the upper shaft cannor freely slide and rotate the mechanical advance will not function so clean and lube upper shaft before reassembly.
Advance Mechanism Problems
Before you harvest a JY dizzy, check the condition of the vacuum advance canister. Approx 2/3 of the canisters I find in JY leak. (check vacuum with a mity-vac or suck by mouth). New vacuum canisters cost approx $25 from nissan, part number 22301-7901 (a 280zx parts listing). Check the condition of the breaker plate assembly. The plate that mounts the trigger wheel should rotate freely. There are two sets of ball bearings that keep the breaker plate sliding smoothly. The 3 bearing on the bottom of the breaker plate assembly (below the fixed plate) are held by a metal cage and are trouble free. The 3 bearings in the middle of the assembly, directly below the moveable breaker plate are retained in a plastic cage that usualy is broken. The grease that lubes the bearings dries up and the feeble plastic bearing cage gets brittle resulting in "floppy cage syndrom". The cage breaks, the bearings are no longer held in place soslip out and the upper portion of moveable plate will be able to "rock" side to side giving imprecise timing and can evetualy damage the magnetic trigger. New replacement breaker plates incorperating the plastic part are supposably available new from Nissan for $35 but I have been able to fix them myself. Dissasemble the breaker plate assembly by removing the circlip holding the bottom metal cage. Pay carefull attention to the position and fit of the various metal plates sandwiched together. These are thin spring-steel plates that the bearings roll on, these shouldnt be worn or grooved by the bearings. It is fairly simple to fabricate a new bearing cage to replace the broken cage. I just found a flat piece of soft plastic with thickness slightly thinner than diameter of the bearing. Using a pair of scissors and a knife, I cut out a new bearing cage to replace the broken cage, works like new. Once assembled, both sets of the bearings are held in place by the "spring" tension of the metal lower bearing cage, it is not terribly important that the homemade replacement bearing cage hold the 3 bearings precisely, you just need the plastic cage to hold the bearings in place while assembling. To re-assemble the breaker plate mechanism, install the lower steel bearing retainer cage without the 3 lower bearings and install the circlip holding the metal retainer in place. Once the circlip is in place, pry each of the spring cage arms upward to slip each bearing into the cage.
For optimum performance with any dizzy you should check and re-curve the mechanical advance curve as necessary. There are literaly hundreds of different stock advance curves used, check my dizzy specs page for further info. For emmisions reasons, not much timing advance is used by factory at idle/low RPM. Better low/midrange performance can be achieved by recurving. A "typical" recurve strategy when using high performance carbs/cams/high compression would be to limit the mechanical RPM advance to15 crank degrees (7.5 dizzy degrees) and then set the initial advance to 20 degrees (for total 35degrees advance). Higher performance engines require even more initial advance and less total (initial+mechanical) advance so the mechanical advance portion becomes really small. Do not just increase your initial advance setting without limiting the mechanical advance or you will likely run too much advance at high RPM (like more than 35-36 degrees) resulting in detonation and engine damage. Swapping springs and weights from a different dizzy (including 6-cylinder) can change the slope of curve of plot for RPM vs degrees advance. Typicaly, you want fairly rapid advance at midrage RPM, with most or all of the mechanical advance finished "early" by around 2500RPM-3000RPM.(crank). Some IE dizzys have two springs on each of the advance weights (4 springs total). There is usualy a stiff spring that returns the weight to 0 advance at low RPM and another spring that is set "loose", without tension at low RPM. This produces a dual slope advance curve with fast initial advance and a more gradual advance at higher RPM. Testing has shown this can be good for HP if the shallow high RPM curve allows gradual advance past the peak torque RPM (where detonation is most likely o occur). I have noticed different orientations of the advance slot for the upper rotor shaft, some slots are aligned radial to the rotor while others dizzys have them angled diagonal to the radial orientation. In order to reduce the amount of mechanical advance, fill in the inner end of the slot that the weight pin travels in with JB weld epoxy. This puts more pre-load on the weight spring to ensure the weight wont bounce at idle speed creating unstable idle. Low RPM throttle response is better with 15-20 degrees of initial advance. By filling in the slot, you limit the amount of mechanical advance so that when the initial advance is increased, you wont have excessive total advance (mechanical + initial). The slope of the advance curve is unchanged by filling the slots, it just effects RPM where the mechanical advance begins to kick in and the length of the advance curve.On the dizzys with radial slot orientation, I have measured that 2.9degrees of mechanical advance (at crank) is added for each 1mm of slot travel. The weight pin in the slot is 5mm diameter, subtract this measurement from the slot length to find the effective slot travel and calculate the degrees advance, confirm any recurving efforts on the running engine with a timing light and tachometer.
Above picture shows the mechanical advance upper rotor shaft with radial orientation advance weight slots. Retaining screw is hidden below rubber plug on upper end. By changing the length of the two slots the amount of mechanical advance can be altered. Turn the shaft 180 degrees in relation to the drive tang to change the spark plug wire arrangement on the cap.
You should have a functional vacuum advance canister for street driving. The vacuum advance canister alters the ignition timing in response to engine load. The vacuum canister does not produce advance under full throttle operation, manifold vacuum is much too low so canister shouldt effect tendancy for engine to ping under full load.. Under partial throttle operation, on the intake stroke the piston pulls against the blockage of the throttle plate so vacuum is produced in the intake manifold and the cylinder receives less than a full charge of air/fuel and retains more of the burnt exhaust gas in the cylinder. This causes the fresh (partial) intake charge to burn slower when ignited so earlier ignition is needed to extract maximum energy from the fuel. Not using vacuum advance will give you no real increase in performance and will decrease your gas milage and increase emmisions unnecessarily for street driving. The vacuum advance canisters can also be recurved. All the EI dizzys use the same canister that is adjusted at the factory for desired advance characteristics. To re-adjust, remove the putty blob on the end of the canister with a high speed grinder to expose the adjustment screws. Inner coaxial pin limits vacuum advance travel, outer grub screw adjust the spring pre-load on the diaphragm. Turning the outer screw counterclokwise reduces the amount of vacuum necessay to initiate advance. If you are using sidedraft carbs and the vacuum signal is decreased, use a gauge to measure vacuum under cruise conditions and then re-set the advance canister to give full advance at this vacuum level. It may take some trial and error to find the correct amount of vacuum advance, I would think that between 15-20 degrees (crank) at 10-15 in Hg would be a good starting place. Advance beyond the initial + mechanical limit of 36 degrees is needed with under high manifold vacuum (low engine load). For each 1mm of travel of the vacuum canister actuating rod, the timing is changed by 4.24 crankshaft degrees. Once you have finished adjusting canister, you must re-seal the threads of the adjusment screws with paint or hardeing silicon putty or air will leak past the threads.
Above picture shows a vacuum advance canister with the travel adjusment pin and spring preload screw removed. If you need to order a new canister, they cost approximatly $25 new from nissan. Part number 22301-7901 as speced for a 280zx dizzy.
For the basics of distributer instalation and adjustment, check this article from Bryan Feldmans website.