DAW

Z-gad, it's not just the ultimate rpm to consider. Rod/stroke has an indirect bearing on cam duration & overlap effects due to the amount of time the piston spends around TDC vs its rate of acceleration on the stroke portion of the cycle. Check that out because certain tuning approaches can take advantage of high or low ratios. I'd follow Norm's advice on cam selection, cam timing, tuning, etc. e.g., I think he likes to run his cam somewhat retarded vs advanced, and this is empirically arrived at by his timeslips. Trust his tips more than generic advice for engines (with longer rods). DAW

I know how that goes with the cart ahead of the horse sometimes. I don't think the 0.030" shaved L28 dished pistons are no good now because you could shave them more, (until they are flat-tops) and run them with L24 rods and an L28 crank (or sell them for that purpose). The low rod/stroke doesn't mean it's a lost cause but since that provides some low-end advantage, you might want to tune and gear in that direction rather than going for a super high redline. DAW

Re the damper springs, they are color-coded by pressure. Their pressure pushes the piston (and needle) down. If you lighten the spring, you can improve the throttle response FOR A GIVEN AIRFLOW. That's why you don't create over-lean by letting the piston raise more swiftly, the more significant factor is the piston's weight and it takes larger increases in carb/engine airflow to lift the piston so much that it creates a lean bog. Altering the rate of rise or initiation of rise raises the needle faster and covers the throttle opening with fuel supply vs inertia of rest piston lag. I believe this is why you saw improvement when you removed the oil-damper plungers...because it let the pistons initiate rise more quickly. If you've got yellow-code, e.g., springs, don't go out and buy some more but if you aren't sure what springs you have, then try the lightest springs and go from there. You'd be better off using light springs and oil-plungers than removing the plungers. I use ATF but I've recently tried synthetic multiple weight (low temp range) oil. I'm not sure if it's better than ATF but it's no worse. The needles you start with when custom tuning should be slightly thicker than what you will end up with, i.e., you are going to remove material to richen...you can't add it back (so remove sparingly). Most recently I used needles from smaller SUs from an L4 SSS dual SU setup. I liked the profile on these vs stock 240Z needles which tend to be lean at cruise rpm. Remember, a smaller carb may have a smaller jet and when you transfer the needle to a larger jet it will be richer but you retain the profile. The tuning of the needles is an empirical endeavor and can't be done without the car. The companies you refer to are good and reliable but no one can tune your car without your car. You can't assume that out of the box the carbs are going to be perfect for your car. Did the carb source ask for your altitude and outside temp range you operate at? DAW

I think that you'd be better off with L24 rods (133mm) instead of L28 (130.4), and better off using a piston with a lower compression ht. than the 38.1mm of the L28. Actually, you'd be better off with an LD28 block bored from 84.5mm to 86mm, Z22E rods (148.6mm) and L28ET pistons for turbo or F54 L28E pistons for na, either way with P90 head. I've described how to do this conversion in previous posts. I've been driving an LD28 shortblock/N42 10:1 engine for a couple of years. DAW

Does anyone know the pin diameter and compression ht (pin ht.) for these pistons? Thanks in advance. DAW

Three things come to mind: 1) Your damper spring may be too stiff for the low-end response you need. You can get SU damper springs from a company called APT. A lighter spring is like shaving weight from the piston; it's easier for the initial tip-in airflow to lift it, which richens and improves throttle response. 2) The SM needle may be too lean at low speeds. I've tuned SU's including custom modifying the needles and SM needles aren't universally the place to start. In some applications the SM's are too lean at low end and too rich at top end. This can be dealt with by turning them down carefully using a drill press and extra fine sandpaper (technique described in "How to Power Tune SU Carbs") in specific increments which correspond to the physical location of the needle in the jet where the over-lean condition occurs. The SM isn't always the place to start due to the transition profile. One thing you could try as a primitive test is to raise both needles into the pistons slightly. The shoulders of the needles are set flush with the base of the piston. You could try retracting them slightly (like 1mm). This will richen across the board. This is just a test, but if 1 or 2mm improves the low-enf response, you know you need to tune the needles. Related to this is the position of the jet. Idle stoichiometry may not ensure that throttle response will be good 1,000 rpm above that. I've found that it's better to put up with an idle quality that is a bit rough in order to have a symmetrical, optimum mixture at higher speeds. Count the turns on each jet setting and record, then run them fully in and set both at 1 1/2 turns and work richward by equal increments of 1/4 turn. Once you stop noticing improvement, stop or you will over-richen at high speed. 3) Vapor lock is a possibility. Are you running the fuel return line? The vapor cannister could help you. Tee the vent lines from the carb bowls and run the line to the carb port of the canister. Fuel tank goes to the marked port on the cannister and dist. vac port goes to the port on the carb that has it for the source of ported vacuum. I'm not sure that these suggestions will do it, but I've tuned out similar problems using them. Good luck! DAW

Dan, I wrote you that I kept getting rejected via the "invalid session" route. After my note, it was remedied for about 10 days and now it's back. I've given up going back and reproducing the posts as I don't have that kind of time to do them 2 or 3 times over again, so I just abandon it. This didn't happen with the old format so I can't help believe it is associated with the transition. I have no assurance that this post will get through; or if I'm just wasting more time. DAW

Dr. Inferno, back to your question...there are a few things you can do to deal with your situation, i.e., high compression engine with EFI: First off, the N42 is an EFI head so you're set there. Newer cars often run 11:1 c.r. but they do it with engine management computer systems that control more parameters than the earlier ECUs, and the cyl head designs, variable cam timing, and multi-valve heads all contribute. So, if you can pull an entire management system of a modern 6-cyl (doesn't matter if it's I6 or V6) with compatible injector impedence & cc flow then you could set up a crank trigger and might be able to go that route. A stand-alone programmable system, although expensive, would be the best solution. With proper tuning and a knock sensor in the circuit you might get by without lowering the c.r. using the above solutions. If funds don't allow and you've got to go with the stock EFI/ECU there are a few tricks that can help performance and protect the engine from detonation. A rising rate fuel pressure regulator will leave the idle mixture alone but increase fuel pressure/flow/richness at higher rpm based on demand (this vs larger injectors which flood it out at idle). EFI mixture is tied to engine temp. Get rid of the 195 degree OEM thermostat and use a 180. Don't run a 160 with the aluminum head, 180 is better. Given that mixture is tied to the water temp/cyl head temp signal (same thermistors, different locations), and lower engine temps are shown as higher thermistor values (cold engines get richer mixtures), you can select a resistance value and add that resistor in line with the sensor so that you richen the mixture. This richens across the board so don't get carried away but you know you're going to need to be richer overall once you increase compression. Another trick, to approach methodically or suffer the consequences, is to adjust the spring tension slightly on the AFM door. Higher airflow/engine speed gets richer mixture than when the door is just ajar. So if you make the ECU think the door is open due to a higher flow than is actually occurring, you get some enhanced enrichenning. These budget measures are a compromise but the'll be a world better than trying to leave a stock system stock with higher compression. If you find you need to enrichen a lot across the board, you might try swapping in L28ET injectors right at the start. In fact, I've wondered about modifying an entire L28ET system (crank angle, knock sensor) for use with a high compression na setup but haven't explored it. Finally, an HKS 2mm head gasket may be the easiest way to lower your c.r. but they're about a hundred bucks. DAW

Here's my $.02: 1) Check around your area for a wrecked 280ZXT and buy the motor with the electronics/ECU intact with the motor. They vary depending on your locale I've seen an engine complete (except for an intact harness and ECU) go for $250 but you've got to be ready to jump on a deal like that. Put the engine in and hook up an intercooler and bump up the boost a bit, then take it from there. 2) Find a '75 (preferably, due to N42 head) or '76-'78 (second choice, due to N47 head) 280Z engine, locate a set of L24 (or L16) rods with 9mm bolts. Remove the dished L28 piston/rods and remove the pistons from the rods. Discard the L28 rods. Have a good machinist turn down the rim of the dish (converting it to a flat-top) just so that the Nissan markings in the base of the dome are barely visible on each piston. Weigh the pistons individually and the rods (L24) individually. Match the rods to pistons for the most consistant unit weights and have the pistons (pins) pressed onto the matched rods. Match piston/rod units by weight with the best corresponding unit matched to it according to how much the two will weigh when they are at TDC when their counterbalancing piston/rods are at BDC. That may be hard to follow but think dynamically about setting up the rotating mass. So, taking down the piston rim allows the use of the 2.6mm longer rods which restores the deck ht.; makes about 9.8:1 c.r. (vs anemic 8.3:1 stock); and converts your engine to a more favorable rod/stroke (133/79 vs 130.4/79). These changes will really wake up the engine, then come header/exhaust, camshaft and induction (look for 2" SUs, triple side drafts, or fuel injection with some mods). 3) There's another approach that involves the use of an LD28 shortblock, but that's a little involved for the stage you're at. Good luck and have fun. DAW

That would be me. The engine runs great. Very smooth, great low-end power, reliable, and starts easier than any car I've ever had in any kind of weather (the LD28 starter probably has more power than an L28). It's in a daily driver for now. I used an N42 head to make about 10:1 c.r. I may omit something since I built it about five years ago...whatever L6 head you use you'll drill the headbolt holes from 10mm to 12mm, preferably using a drill press. In some places you'll use the LD28 headbolts with an extra washer, in others you'll use early (70s-80s) BMW headbolts (from either an I4 or I6). Torque to LD28 specs. I may have drilled some water passage holes in the block deck to match coolant passages in the head (I can't remember if it was this engine or an LZ4 block with L4 head that I did this on). Drill block at dipstick boss in block for rear sump pan use if motor is going into a Zcar. I used an LD28 head gasket (which come in different thicknesses). In fact, it's a sturdy gasket and I reused the same one. You'll need to remove the timing cover section of the head gasket and replace it with an L4 or L6 section. Use a timing cover and chain from an L20B. I wanted to use the LD28 water pump as it obviously had more capacity than an L4 or L6 pump. In order to do this, I had to grind some clearance between the impeller and L-series timing cover. You could use a stock L6 pump without any grinding. I think I also had some minor pulley alignment problems when I retained the LD28 water pump onto the L20B timing cover, but this was partially due to power steering pulley. I used the hefty LD28 alternator. It has a big vacuum pump integral to it. (Might be useful in a turbo car) I removed the impeller to disable it and blocked oil flow to it. I believe doing this also increased the capacity of the oil pump because the oil system to the vacuum pump appears to be of significant volume. Given the larger volume of the complete oil system of the LD28 I used the LD28 oil pump as I figured it was closer to an L28ET pump than an L28E pump. You can use the entire f.i. intake and EFI system from an L28E for starters. I lightened the AFM door spring pressure slightly and placed some added resistance into the water temp sensor circuit to enrichen and I think I set initial timing to 12 degrees. Timing is read off the flywheel and it only shows TDC (because it's a diesel block) so you'll need to figure out 12 degrees. I think that's about it...I'm using a 3LN71B trans behind it using the lower stall speed torque convertor and have no problems, it jumps forward when you apply power off idle. This trans has a hydraulically locking convertor which is nice because it drives like a 4spd a/t. There is a significant difference between the tooth profile of the LD28 ring gear and starter gear than that of the L6s. For a m/t car, you'd probably be happier with L6 driveline than LD28 pieces. Well, you asked so there it is. Good luck. BTW, the oil inside the LD28 is pitch black...you're going to be a mess. DAW

Did you drill oiling holes into the small ends of the rods to provide lubrication to the now-mobile piston pins? DAW

McAdam, if you really want to keep your long-rod L6 project on a budget you can leave the LD28 short block basically intact and use an N42 head for n/a or a P90 for turbo. You'll end up with 83mm stroke, 84.5mm bore, 140mm rods with large floating pins, sturdy pistons with c.ht. = 46.5mm. That's a bit tall on the comp. ht., but with a turbo you won't need high rpm to get power. With the n/a setup I'm using an N42 which should be around 10:1 and I've never heard a ping. Compression cranking pressure is 210-220 already but I'm considering switching to a Maxima N47 head to boost compression higher, or to turbocharge it with the N42 using low-pressure turbo. If you want to go for more hp and higher rod/stroke, you can do the overbore and swap in shorter pistons with longer rods as you are considerring. Use 184.5mm as your working length for rod + comp. ht. That's what zero deck ht. stock is (140mm + 46.5mm = 186.50mm). The Z20 rods aren't very meaty looking. One budget possibility would be Z22E (not S) rods (148.6mm), and L28ET pistons (38.1) for a distance of 186.7mm and a good r/s and a good c.r. with a P90 head (a bit higher than the stock L28ET due to the displacement increase over 2.8L from the overbore). Even if you go n/a and use a Maxima N47 head, the turbo pistons will be sturdier than the non-turbo stock Nissan pistons you're considerring. Finally, don't let anyone talk you out of what you're ponderring as it not only can be done; it's not that difficult to do. DAW

How heavy is the Volvo 3 liter 24-valve I6 (used in 960 GLEs)? Motronic engine mgmt, etc. European market Volvos use M/Ts in many cars that are offered in the U.S. with A/Ts only. I had a 960 Turbo wagon with a 2.3 liter intercooled 8-valve I4 A/T that I bought from a dealer in Italy then picked it up at the factory in Goetenburg, Sweden. It was surprisingly strong but that's not the point. The point is that when I road tested the car in Italy the dealer only had the European market version of the car which looked the same but had a 2 liter intercooled 16-valve I4 with a 5 spd and it hauled ***! So I've got to wonder if there is a European version of the multivalve I6 with a M/T that would be a nice fit into an early Z. If you have a friend in the U.S. armed forces in Europe, maybe they could start sending you the pieces via A.P.O. U.S. Mail. DAW

Jeff, I missed the earlier discussion on this system...what is the price? Thanks. DAW

I've seen these in a Japanese Replacement Engine warehouse...JDM na engines using the P90 instead of the P79 head. I suspect Japan doesn't have our emission regulations which dictate use of exhaust port liners (ala P79). DAW BTW, I suspect there is a "Maxima" type N47 closed chamber head from JDM which would have square ports instead of round/liners ports...anyone know for sure? DAW

There is a way to do a 1/2 link shorten, it involves removal of one roller only; not two, by using a special side plates that are wide at the end attaching to the outside of one end of the chain, and narrow at the end with the roller which attaches to the other end of the chain. You would remove a full link from the chain and install a 1/2 link. I'm not saying that this is sure to work, but I've not seen the idea discussed before. However, the 1/2 link approach may still be too much distance to remove from the chain...I haven't measured to see. The needed chain length change would not equal 0.080" of course, the easiest way would be to check a stock chain on a shaved head with the cam in place but without the tower shims in place. Tensioner modifications don't help because the stock chain is just too long if the towers aren't shimmed. BTW, you don't need to buy new lash pads if you do the 0.080" shave/shim technique as long as you swap in N42/47 valves, their added length is the same as the added thickness of lash pad you'd need if keeping the P79/90 valves. DAW

You should be OK and the same clearance as using an N42/47 head with flat tops because the P79/90 valves are 0.080" (int) and 0.090" (exh) shorter than the N42/47 valves and you are cutting 0.080" from the head which moves the valve edges to where they would be anyway with respect to the piston top using an N42/47. The reason that the longer N42/47 valves are transferred into the shaved P79/90 and thick valve spring shims placed, is to restore the cam geometry since the towers and cam had to be shimmed up 0.080" to take up timing chain slack. Now that I think about it, when I set up my son's go kart chain I used a 1/2 link to obtain the needed chain length. Maybe the P79/90 could be shaved 0.080" but instead of the accompanying cam tower shimming, valve swapping, etc. the chain could be shortened by 1/2 link...or an alternate diameter cam/crank sprocket could be used. This would greatly simplify building a flattop piston/closed-chamber-head engine. DAW

TempeZ hit it right on the head, so to speak. You'll want to swap cam and intake valve springs with those from an L28 head. For use on a 2.8, especially with an overbore, you'll need to have the 44mm L28 intake valves and new seats installed into the L24 head to replace the 42mm intakes. I'd suggest you find a core/useable L28 head, either N42 or N47 (not P79 or P90) as the source for your donor valves, springs, and cam. P79 valves will be too short to use in the Maxima N47 head. BlueValoZ, I'm not sure about that early L24 810 head...if the same part# pistons and the same c.r. match up then I'd assume the head uses the same chamber as the later Maxima L24 heads. DAW

The thing is that the engine harness is absolutely essential and is the heart of the swap...just leave it intact and you're halfway there. There is an interface, if memory serves me, with another harness but it is minimal and I think that may be what the others are referring to re "only three wires" to hook up. Once I stripped a zxt and cut the whole car up with a torch, leaving only the engine/trans assy with the electrical harness I'm referring to, as well as the ignition/alternator harness, the fuel lines and tank, and a battery...and I could fire the engine up at will; and it was all ready to drop into a 240Z as-is. DAW

The harness you need is basically intact as one unit. Start at the fuel pump and remove the harness (dark green wire) from there forward to the ECU, push the ECU connector through the firewall hole (along with the fuel pump wire) and leave this harness on the engine (connects to injectors, sensors, distrib, etc. I would strongly suggest that you not unwrap, cut, separate or alter this engine management harness. You will be way ahead of the game if you transfer the L28ET with this harness intact, into the 240Z then transfer the fuel pump and ECU from the zxt; hook it up and start it. Once you've fired it up then go back and alter the turbo or whatever you want to do to it. DAW

Get rid of the POV, most turbo engines don't have one. I used a pipe plug which threads right in (1" or 1 1/4") but it's galvanized steel and looks crude I'm sure you could find brass. A member suggested that there is a manifold plug on the VG30ET that fits...you could check it out. DAW

About the roll bar, in SCCA Solo I and II you don't have to have a roll bar. In terms of fun factor, you can go out and race as-is. Find yourself a helmet and have at it. Beef up your brakes for Solo I. DAW

Run a compression test on the 280ZX motor (preferably hot). If it's fairly even and within spec across the board, then there's no problem. I agree with the others above, 120K is nothing for a Nissan L6 if it's been maintained. DAW

It's not the valve spring strength that's the big problem with brass seats as in the E88 head, it's that they are for use with leaded gas which has lubricating properties vs unleaded which does not. You need hardened seats as in post-'74 heads (N42, N47, P79, P90). Since you need to replace seats anyway, you could have L28 seats put in the E88 head and use the larger L28 valves to upgrade the valve size too. However, be aware that 280ZX valves (P79, P90) are shorter than 280Z valves so don't plan on swapping out those from that P79 you have. I think you'd be better off in the long run if you found an N42/N47 to put on your 280ZX. There is a way to shave and shim your P79 by 0.080" to increase compression, but it requires the transplant of a set of 280Z valves which are longer than the 280ZX valves. DAW

Weber side draft have chokes but they aren't butterfly valve type. They provide enrichment and fast idle and, since Webers have accelerator pumps, they generally have better cold-start characteristics than the stock SU carbs. The car sounds good (depending on the price) but I'm wondering about the diff. With that many mods, one would expect a good, strong, LSD diff. To not have info on it may suggest that it was sold or blown up and replaced with a stock diff. With a 1:1 5spd you should have the ratio info too. Given the vintage of the mods, an R190 LSD would not be surprising. You didn't mention a roll cage so I assume it's not road race ready but it sounds like a fun Solo I or II car. DAW