DAW

I'm setting up a five lug/big brake budget conversion on the front of my '75 280ZT and I'm about to fabricate caliper mounting brackets.

The A/T car uses an oil cooler that the M/T car doesn't have, thus the higher flow. I was thinking the A/T pump cost more than the M/T. If not, then I'd go with the A/T pump, with or without an oil cooler. DAW

There's a book, ISBN 1 901295 64 8, "How to Build & Power Tune Weber & Dellorto DCOE & DHLA Carburetors", Veloce Speed Pro books. Get that book, then ask for supplemental suggestions. The book will walk you through proper jetting and tuning. I lived in Naples, Italy for a couple of years and I used to peruse the junkyards there looking for Webers. I brought back many dual sidedraft setups, some from Alfa Romeo police cars. I picked up Weber, Solex, and Dellorto 40mm duals. I was surprised to find that many of the Italian mechanics preferred Delorotos, as I always assumed Weber would be the top dog. DAW

At the risk of sounding oversimplistic, I'll offer some possibilities. The sudden onset narrows the troubleshooting scope some. A arb linkage problem could have put the two SUs way out of sync, including the fast idle/jet retractor linkage stuck on one carb; a suction piston could be stuck down in one carb due to varnish build-up; you may have a bad tank of gasoline; you may have a carb float stuck partially shut or a gummy restriction in the fuel supply line to one carb, you may have an ignition system problem (which shows up under load and throttle blips, idles but won't accelerate). To crudely narrow this list down some, you could remove a plug wire, put a phillips srewdriver tip in its end and hold it 1/4" from a ground with the car running, spark should be blue and stout, if it's feeble and orange or won't jump the gap, you may need ignition system work. Pull the air cleaner and lift an SU piston with your index finger: same effort to lift each? Do they drop about the same if you let them go from top of travel? Check the linkage for missing screws, etc, and work the choke: do you have full travel at the carbs for each carb? Push off choke: are both jets returning to the off position? You may have to run the car and individually to each carb, apply some choke (...wait a minute, did you say 260Z? If it's stock, then you'd have HIF squaretop SU/Hitachis and have a choke plate, not a mobile mainjet...oops) DAW

I think the POV is overkill for even the stock engine. What other OEM setups use a POV in addition to the wastegate for boost regulation? None that I know of. The BOV (compressor by-pass) has a different function and is on the other side of the throttle plate. The POV is a fail-safe, last resort mechanism; while the BOV relieves power robbing, impeller slowing pessure build up between a closed throttle plate and the turbo. BTW I've bought an expensive BOV before and found the one from an OEM Eclipse/Talon from the wrecking yard works as well. I haven't removed mine yet but plan to. Did you use a pipe plug and, if so, was it a standard pipe thread of what size? DAW

Jeff, I can't get my scanner to cooperate, which is frustrating because the schematic is sitting right here but no image. Sorry, try your local library and sometimes they'll surprise you by having Mitchell Repair Manuals for reference. Two other options: Haynes (look for wiring diagram before purchase), or the CD Nissan Service Manuals available on this site/Hybrid Z Store. DAW

Is it intercooled? An intercooler and a compressor bypass valve are always good to have. External wastegate? Once you've intercooled, it's too easy to bump up the boost by playing with the wastegate. See Corky Bell's book: "Maximun Boost". DAW

combustion chamber size (Maxima is smaller); at least that is what I've read many times on this and other forums. DAW

I may be wrong about Jeep as a source of 5-lug wheels/hubs. I noticed the other day that Cherokees and Comanchee (pickups) come in 2WD and that '89 Comanchee spindle/inner bearing race diameters match 240/280Z. DAW

It's on the scanner as we speak but scanner not cooperating. This thing is big, folds out to about 6 pages...is there any area in particular of concern? DAW

I'm considering my options for a five-lug conversion coupled with brake upgrade. Budget constraints limit me to salvage yard parts sourcing. I looked at

I've got a '77 Factory service manual and I'll plan on scanning & sending but it'll probably be 12-24hrs before I can DAW

I'm not sure of the exact cc's of the Maxima N47, I've relied on the specs in "How to Modify Datsun/Nissan Engines" book and that head is not specifically mentioned, just the N47 head from the 280Z. I have seen the numbers before in these postings and it's a modest difference. One could work backwards if the Maxima L24 dish and c.r. were known, and knowing the 280Z c.r. of 8.3 and dish of 10.9 with the comb chamber cc of the 280Z with the N47...it can be calculated. As to the alteration of the compression ht and removal of dish on the '75-'78 L28 pistons, I had my machinist take down the dish edge carefully until it was just gone. The last pass left machining marks across the entire top of the piston but so superficial that you could still read the factory "oversize" markings on the piston tops. I wrote down the new compression ht measurements which, with a recent move, I can't find at the moment...however, they were approximately the same change from stock 38.1mm as the change from L28 rod = 130.4mm and L24 rod = 133mm, giving no significant change in deck ht, loosing 10.9cc of combustion volume, and increasing rod/stroke. The key question is whether the top ring is placed too close to the deck by this change. I think that distance has been growing less anyway on newer cars as this space is a source of emmissions from what I remember reading somewhere. I'd like to know the Maxima combustion chamber cc too, anyone?? DAW

Honda, Mazda, Toyota, etc all have a variable runner system in some form on some of their performance vehicles, including SUVs. The design I'm describing accomplishes the same end result, but I believe possibly in a smoother, simpler fashion that is directly meshed with the load demands of the engine so that it creates the "type" of power curve needed by the vehicle at any given driving condition. The fact that the SU is a carburetor is incidental to some extent. The needles could be removed, main jet plugged, fuel bowl removed, etc and a fuel injection/engine mgmt system (for fuel delivery at the intake port) added to dispense fuel. What the SUs are being used for is their airflow regulatory properties. The feature of the SU which makes it such an elegant, self-contained, induction modulator in the first place is being expanded upon in this variable-intake design. Instead of throttle plates, solenoids, and vacuum diaphrams, this design directly uses the engine's own flow to maximize/tailor...it's own flow. If one were to suck on two straws in a glass of water simultaneously and one straw is twice the diameter of the other, The smaller straw would have the liquid up to you much faster, responsively; than the big straw. However, with a big pull, the small straw would hit some limit of how much liquid it could supply, while the big straw (although not quick) can deliver huge amounts of liquid flow. Changes in suction at this high flow state effect almost entirely the large straw side because the small straw has become, essentially, a fixed orfice/resistance value. We're just applying the fluid characteristics of air to do the same thing the water would. DAW

Thanks, yeah I know I'm talking ignition only on the salvage parts, but that's what I'm after. I've got an optical trigger (Crane) set-up on my Solo II Street Prepared early Z, (high compression, triple Solexes, 4.44) and I just want to bump up a notch on the ignition. Has anyone used a L28ET engine mgmt (computer) system, including knock-sensor retard, on a high compression na L28E? DAW

There are a whole bunch of those Buicks & Saturns out there that I'm referring to and I haven't seen an inordinate number of those cars off on the side of the road, which bespeaks Electromotive dependability and reliability. SDS is fine too, although GM didn't buy rights to their product. What I want to know is how can I get something for nothing?? i.e., pull a scrapyard Electromotive system and use it on my hotrod Datsun Z without spending an arm and/or a leg? DAW

That's what I suspected, that Electromotive licensed their product to GM, etc. Has anyone pirated one of these factory systems to use on a hybrid Z car? If so, is the wiring schematic available? DAW

The latest generation cars are pulling more horsepower and torque by incorporating variable intake manifolds. Most have a regulator valve of some sort which directs induction charge from long runner for low end torque to short runner for high end flow/horsepower. This system uses internal control valves (SU suction pistons) to accomplish the same thing but more simply/directly. This design began with an attempt to build a tri-SU L6 and evolved from there. I have many of the pieces for the prototype and it does not depend on a cast aluminum manifold. I'll post pics when it's ready. DAW

The L18 carbs are smaller, unless they were changed from SSS setup. If they have two mounting bolt flange, rather than four, they're too small for your Z. DAW

I've noticed that several car mfgs use a sensor-triggered distributorless ignition system (e.g. Buick 3.8 V6) whose components look just like TEC-II externally. Does anyone know if these systems are functionally the same? Did Electromotive sell the design to Buick, Saturn, etc? I picked up a Buick set-up at no cost and was thinking of using an '81 L28ET damper & TDC sensor unit to put together an ignition system for my na L28. Any experience with these ignitions, altering maps, etc? DAW

So I'm designing this and I wonder if anyone has done a similar design? Basically a two stage induction system with a few key features: for L6 application, paired small diameter runners are grouped according to ignition intervals, i.e., 1&6, 2&5, 3&4. Each pair (all 6 runners are equal length) joins briefly at a small plenum to which a small SU is attached, sans throttle rod and plate (rod holes capped). SU piston spring set low tension, quick response. Each of the three pairs configured same so 3 SUs (small, like 1 1/4" or smaller), without throttle plates. Each airhorn side has a flexible air intake hose joining to a plenum which has mounted to it a large throttle body/air filter. Also attached to this main plenum via flexible air hose, is a large, single (maybe double later) SU serving the log-type plenum immediately near the cyl head, with short runners which each "Y" connect to the long, primary, runners. The single SU is a large unit fitted with an emissions-type piston weight, a strong piston spring, and a rich needle. This SU also has the throttle plate and rod removed and ends sealed. Operation: One throttle plate is actuated by accelerator, low speed airflow can't lift heavy secondary SU piston so the secondary/short ram system isn't activated until high progressive engine speed. Low speed airflow is, however, well balanced due to ignition interval match-up, and charge speed is optimal. High charge speed enhances fuel atomization, and produces great torque and responsiveness. The key to this system is that the same factors that allow the primary system to respond quickly (column/pressure-effect), become limiting (flow-restricted by small diameter SUs and long, narrow runners), such that the primary system becomes effectively, a pneumatic plug that the engine can't move as R.P.M. increases. However, as that occurs, the engine can move/decrease another plug which activates the secondary system: the large SU serving the short ram/runners manifold. So, the 3 small SUs are pegged open now and heavy duty, high flow tasks are via this large SU (or two, maybe) augmenting the wide-open primary; and all are in response to the accelerator pedal. When power/rpm falls off, like on a hill, the secondary system automatically cuts itself back (as its heavy piston is the first to fall when airflow drops); which puts acceleration back into the high-torque/lower-flow primary system, just where it needs to be to get the rpm back up. SU calibration is done by needle choice, piston spring choice, and size of primary SUs used, with respect to tuning for primary/secondary transistion at given R.P.M. (different for rally vs road vs autocross). So, for those waiting for a tri-SU set-up on the Nissan L6, here it is plus one or two more SUs to boot. DAW

I dug up the photos and I guess I forgot just how bad they are. Let me shoot some more, in better light, and I'll get in touch. Thanks, DAW By the way, I noticed that CA20E pistons share bore size with LD28 = 84.5mm; does anyone know pin size, compression ht, & dish of the CA20E piston? Also, there is a good discussion of rod/stroke ratio and effect on peformance in "How to Hot Rod & Race Datsuns", author is Waar, I think. DAW

Thanks. I'm more interested in doing the technical experiments than in trying to squeeze through trackside inspections. I'm more likely to run an autocross for "time only" than to hassle with Street Prepared or Street Modified rules. Solo I is also a great place to flog the car. I've got a few engine bay photos around on Kodak disc but I don't have an html. I'd welcome someone to help me post these. DAW

Thanks, and yes I'd like some info on the build-up. I presently have one E4N71B from a normally aspirated 300ZX, and one from a 300ZXT. My info says the na has 2150-2450; and the turbo 2500-2800 stock stall speed. I was going to fit either with the Lseries A/T bellhousing. I guess if I get the urge to run an autocross course I'd be better off with the higher stall speed even with na engine. I'm not a big A/T type, but I know the '82-'83 280ZXTs were faster than the 5spds (turbo revs are kept up better with gearshifts in an A/T vs M/T), either one benefits from a compressor by-pass valve (left off by Nissan along with the intercooler). If you have any budget-minded tips for the L4N71B, please pass them along. I can fix the tran(s) up before installing in the car. DAW

You lift up the engine (mounts unbolted) in order to drop the pan and, with the head off, can push the piston/rods out through the deck. You are going to have to pull the front cover because you'll need to rotate the crank and therefore can't block the timing chain. Remember, the top-end of the engine can be removed as an assembly, there's no need to unbolt components, i.e., intake manifold, exhaust manifold, etc, just pull it as a unit. DAW