Lazeum

Engine still runs strong and smooth. I did not make any progress in tuning yet but car is very driveable the way it is now. Today, I was passing somebody on forest road, going WOT up to 4500-5000 rpm. When I was just passing the other car in a loud Braaap! Suddenly,the Z made a huge BANG! from the exhaust while still at WOT! I've probably scared the hell out of the other driver who did not ask anything (but he was slow, way under speed limit). Car is still running strong with no side effect but I need to understand what happened. Next time, I'll plug the wideband and record. From my list, it could be: - too lean mixture (it was perfect at 12:1 before MJLJ switch) - not enough timing - 1st suspect in my mind - I'm running 32° max for now. - exhaust leak? - I've set up soft rev limiter at 5000rpm (still breaking-in) - could it be the reason?

I've been one of the "smart" engineers defining how much time it could take to perform some operations on cars. It is a task that OEM & system suppliers (me) have got huge debate (and tons of useless meetings). Me, as a supplier, had no gain or what so ever to change operation time but I was responsible for proper procedure (there're always many), proper tools & timing. I have found that final outcome is not always the smartest & most of the time, new tools have to be created (whereas job could be done with regular tools - but would require 5 extra minutes). New tools? to define if it is useful, OEM estimate how many cars official dealer would have to work on, take the cost of tools & divide the cost of tools per numbers of cars to fix. You get the answer if it is relevant to purchase new tools (at dealer expense of course - tool is having a license for one tool maker to produce at its given price ). With such process, you can start to understand why flat-rate are not always relevant. Of course time is defined with a skilled mechanic that can do the work blind which does not help either. A fair way of doing business would be to charge actual time and parts but with the mass of dealers, shops, mechanics where you cannot assume skills & problem solving accuracy, you have to find a way of being fair for customers. It is ruled out by OEM, at the end, it is not fair either... Imagine you go to a shop, they charge you $500 for exhaust replacement: parts & time. A friend of you with same car goes to another dealer & got charged $400 for the same exact work because shop #2 works faster. You would change immediately your shop. If those shops are auto dealer, OEM management would put tons of pressure on first shop to get better until they become faster than dealer #2. Then, dealer #2 would have to improve also their efficiency since shop #1 is now better, and so on.... It will not work on a large scale picture, especially when money & OEM are involved.

The bolts becoming loose overtime because of engine torque is a myth to me. We do not tighten every bolts on ZR1, GTR, Ferrari's (maybe not Ferrari's ), etc. whereas they've got torque. Lack of unibody stiffness is not a reason to explain either why bolts get loose. Most likely, bolts were not torqued properly. Reasons could be many: bolts already stretched a little, thread contaminated (rust, dust), improper bolt quality, etc. If you reuse bolts, this is probably the reason. I used also to retorque bolts (stock units), I've replaced them all with new bolts, clean threads, get them torqued properly. They never get loose now. Checking bolts after every event, as Mike is suggesting, is not a bad idea though. Our car are like prototypes since we all mess up with them in every way.

Here are the files modified with lessons learned since I've installed everything in the car to create your own VR sensor bracket. I've also driven the car, it was very nice with no issue. Car is smoother than before, power is ok (same level than before with Dizzy) but map is not done yet, I've change it once only. I've got "pop's" from the exhaust while going uphill under load, it needs more advance at low rpm & much more under load & low TPS angle. I also had to raise idle speed whereas it was ok with dizzy. not sure why, I haven't touched carbs in the whole process. Only mechanical change to the engine was e-fans instead of regular fan. So far I'm running idle timing at 20°, max at 33° @ 3500rpm. VR Sensor Bracket - Datsun 240z.zip

My dad had got a Z3 coupe with 3.0L. The car felt very close to the z in term of behavior with seats close to rear drivetrain. Power wise, it was close to my previous L28. It was just more refined. I had also a Silvia s14, 200 sx with sr20det in Europe. Handling, stock, was very bad. S2000 would have my vote also but I'm 6"2 with 210lbs. I don't fit inside. It is just impossible to heel-toe, double clutch. Same goes for Miata, fun but way to small inside. Over priced & very expensive to maintain but my best car was a Mitsu Evo, handling, power, 4 seats. It was great.

Power on engine is done with clean & efficient combustion at the right time. Timing is key! If you have poor timing management, you're not going to use full potential of your build. DCOE or SU, it doesn't matter. With a stroker (so $$$$ invested), it is a waste not to invest on something good to manage timing. - Either you get a dizzy recurved to proper specs (do you know them? ) with no excessive shaft play or wear in your system, of course! Mallory Unilite allows it but it costs some money. - or you go with locked mechanism and timing management such as MSD AL2 system. You can play with timing with the box. - or distributorless with full timing management - Megasquirt, Megajolt, Electromotive XDI, etc. For "race engine", you're only focusing on WOT (intake fully opened => Intake pressure = Patm, so no vacuum). What matters is Max total timing. Good Idle timing is also good to have while you're waiting to go For street engine, where WOT is only a part of the use of an engine, the lack of vacuum makes the engine burn air/fuel mix too late since mixture will burn slower. 2 choices to overcome this situation: - You run richer AFR - this is what you do with recurved dizzy with no vacuum advance. Fuel economy gets bad. - You increase advance timing - this is what stock dizzy with vacuum does, this is what distributorless system with full timing management can do also. Engine efficiency is best. Timing at idle should be set where engine run best. You should only limit the amount of air going inside the engine, you should set AFR where engine runs best, you should set timing where engine runs best also. Best means here most efficient combustion. With regular dizzy with no vacuum advance, it means you can get your dizzy a little loose, make the engine run and turn slowly the dizzy by hands until you've reached max rpm. To get back on DCOE, you should tune first idle, it should run smooth first. With 50f9 & 33mm chokes, you shouldn't be that far off. This is what I'm running with L28 with head job & 32mm chokes. You should also check everything on the carbs: fuel bowl level, shape of jets, etc. When I purchased the Z with Webers, they were supposedly fully rebuilt but fuel level were not even & in specs, needle valves were shot & crushed (so one needle jet never got closed = fuel level never stop raising with fuel flow), idle jets were having grooves at taper, etc. I've made the engine running "good" before I noticed all the defects, I had to start again from scratch. To set idle, there's 2 methods: - get AFR at 14:1 or so with a wideband - use best lean idle method - I've run this one with good results.

I've run the car today. Just for information, my tach is working flawlessly the way it is wired now. Tuning process will be able to start soon.

Sure, I will but regarding tuning and performance, I'll switch to my Megajolt ignition topic. If some noise occurs or some facts about rockers happen, I'll report here my feedback.

I've run the car for 2 minutes. The tapping sound is gone on my car also for now The engine is quiet (it I can say so with Triples & headers) I did not have time to run it for good, I nned to tune ignition first. So far, it is total success It is a Rebello cam with "tight valve lash". It is setup at 0.006" at cam lobe meaning 0.009" at rocker tip, where I'm doing measurement.

Me too, I'm knocking on wood. A French translation would be "I'm sqeezing my a$s up" There's also a small rake on the tips. It was also easy to do. Since the dremel tool was a cylinder, I just had to play a little with the angle I was holding the tool. I was able to see exactly what I was doing with the area being ground.

rockers are done! Tomorrow, they're going back on the engine. It was very easy to do. I've done it with a dremel, only the weight of the tool was enough to grind extra material. The rockers are not that hard. Since the load to be apply was very small, it is also easy to follow the current shape of the part. I've completed the job with a polishing operation to get smooth surface on rocker tip. Grinding operation on 9 rockers took me 20 minutes while taking my time to do it right. Polishing took me another 20 minutes. I've spent also some time to get them super clean since burrs were all over the rockers. So hopefully, it would work. Here are the 3 steps: before => ground => polished. ("Polished" picture is from a different rocker - I was more focusing about the job than on pictures...)

First, Tony, I'm sorry to have made an example with only 4 why's answered I could have named fishbone diagram with its real name but fishbone is easier to remember with its shape. Ishikawa is indeed the author of such tool. We do not have all knowledge to fix everything (I wish I could!), I think it is the benefit of a huge forum, such as hbz, full of knowledgeable people to help the ones who need help. I think it should start first with how to tackle situations. At least, we can refer to this topic or "HBZ not being automotive 101". If the tool are not appropriately used, we are many that could make sure to bring back on track the analysis to make it efficient. Sometimes I see posts, I don't even want to answer, only because of the way the OP tries to fix it. I see also too many posts with shotgunning operation; one small target in the "dark", a riffle of solutions to expect to fix the issue. On topic such as "Engine power is not good" could end up with new fuel pump, new regulator, tuning session, new alternator, etc. whereas issue is due to clogged fuel filter which cost $3. (then, "why was the fuel filter clogged?" becomes the next step) What about "car do not start" followed by "spark plugs were fouled, I've changed them! Issue is fixed!" without knowing why in the first place spark plugs were fouled (= it will happen again!) I think some discipline would save time & money to all. I wasn't convinced when I've graduated from School, now I am. I'm even spending time writing posts about it! The only topic where this method does not work is with women, there's something irrational that makes 5-why analysis irrelevant

I see a lot of topics: "please help!", "why it does not work?", etc. As a mechanical engineer, I've been following some basic methods to solve issues. As obvious as it could seem for some, it seems everyone is not following the same path. What about we try to gather methods to solve problem by ourself? I believe everyone should do his homework first prior to request some help. Most of the time, first answers from members are other questions. What about we try to provide some answers to questions instead? Of course, the first move should be to search for already known issues. there's tons of lessons learned to be shared on this board. OEM's are using some problem solving form such as 8D at GM. it helps to: - Define the issue - Prevent it (in the industry, it usually mean "check parts & scrap bad ones" ) - Find the root cause - Find a corrective action - Make sure it solved for good 2 very basic tools, one is a method "5-why", the second tool is to move forward in the process: fishbone diagram. 5-why. This is what I'm using when I have a problem: I ask myself why, why, why until I've got a root cause to solve. Usually at the 5th "why", we've got the answer. The goal is not only to solve the issue but also to prevent it to happen again. That's very basic quality process. Example: Issue: My headlights do not work. 1st why: Why don't they work? -> Bulbs are broken? - no -> Fuses have melted? - Yes -> Harness is damaged? - No, checked with ohmmeter -> Connectors are bad/corroded? - No, they look ok -> Headlight switch damaged? - No, it was in good shape -> etc. - because there's probably 10 more items to be added if we'd like. 2nd why: Why did my fuses melt? -> Fuses are too weak? - No, they were 15A (instead of 10A) -> Fuses holder is corroded? - No -> Corrosion in connectors? - No, I've checked earlier -> corrosion in headlight housing? - No + when I disconnect them, fuses no longer blow (hint!) -> I've got a wire grounded somewhere? - No, every ground is showing continuity with chassis & Engine -> I've got a short somewhere ? - I notice position light bulb (inside headlight housing in my case) is having 10V instead of ground & 12V from regular signal wire. 3rd why: Why do I have 10V & 12V at position light bulb? and why position light issue would interfere with headlights? -> Wire is damaged somewhere ? - No, everything is good as stated above. -> Because I've hacked my headlight harness to pass European regulation with +12V signal taken from side markers? Human related error? how could that be? -> Because I've hacked my headlight harness to bring a ground to position light bulb? I've got +10V instead of ground! I've added a wire going from a black wire labeled "ground" to position light bulb. 4th why: Why "ground" black wire is providing +10V instead of being ground? -> Nissan/Datsun did a mistake? -> Previous owner has hacked also the harness thus changing everything? - Obviously yes since no wire has the correct color coding when referring to service manual. -> Because I haven't checked proper tension before setting everything up? No need for 5th why here ! The causes of the issue: -> Harness has been modified -> I did not check everything while doing the work - Lesson learned! (hopefully!) -> Wires are improperly crimped together, I had to changed the way they were setup. I've controlled everything with a voltmeter during the process! Problem is solved & I'm positive it won't come back. Fishbone diagram or cause-and-effect diagram This one helps to get proposal for every "why". It starts with a consequence: "fuses have melted" for instance We should split then items into categories. the book is saying to split them into 5 major ones: People, Methods, Machines, Materials, Measurements, Environment. I don't usually follow exactly those steps. The point is to think about anything that could be the cause, it is a brainstorming step. This is where forum community could help the most. Image from Wiki: In materials, we would have broken wires & harnesses, corrosion issues, too weak fuses, etc. In Environment, we could also have corrosion, debris somewhere, salt in connectors In people, we could have fuses improperly clamped, etc. Management category here is useless With such process, we've got tons of stuff to do to make sure we don't miss anything. If everything is done right, nothing would be missed! This is how I've fixed headlights issue that was there for 3 years in my car in 2 days. I was just driving the car during summer time with day light to go around the issue Since it was pulling power from the system, my car was also stalling at red lights sometimes...call me stupid! These are also the basic tools that avoided my company to recall 300,000 cars because of issues....

Everything is running but I've got some side projects to take care of prior to run the car and tune it: gas tank, fuses blowing and engine tapping. Gas tank is done, I found why fuses were melting, I still need to take care of rockers. The car should be on the roads by next week

Your MJLJ ignition helps I'm sure. I can't wait to tune mine I'll be able to experience the different between "regular" mech advance system & full 3D ignition (I've chosen TPS for now)

Leon, how's your timing? Do you think it is optimized? I believe if you're using advance correction with MAP or TPS, it could also help when going at WOT in lower gears. Car sounds good & healthy too!

My location is a small detail . It was much easier to work on cars while I was living in Michigan! I would have been tempted to grind the entire width of the rocker. Filing down the edge only should not create any problem with geometry, that sounds obvious but I did not think about it immediately. Your picture makes perfect sense. Thanks!

I'll probably try to grind them down by myself. Money is not so tight on my side but I find it ridiculous to spend $100 in shipping for rockers. I've got a grinding wheel at home that should do the trick. I agree with you regarding wear that should self wear the tip to get proper contact. I'll have to keep track of valve clearance to compensate wear over time.

Thanks Jim for your answer I've been trying to find an engine shop which would be able to regrind the rocker tip with appropriate tooling locally in France. It is too specific, nobody can do it, even cam shop. Would it be an option to grind those rocker tip by myself? I'm anxious to proceed with such task without controlling parallism of tip surface vs. cam profile. I could try to make a fixture to help me with such task Only option to make a clean job would be to ship the rockers overseas to the US. I'll spend twice the money to grind current rockers vs. new units (that would require new custom lash pads most likely) As you said, we can see some wear on the middle of the lash pads showing that contact happens. parts would wear out until they get full contact. So filling down the edges could be an option maybe...

Since I was having the same noise on valve train as the one we can hear on the video, I decided to have a look at my rockers. I thought valve train noise was normal so I was living with it. The following pics are showing you how my rockers & lash pads look like. Out of 12, only 3 are in good shape with expected wear... All rockers on cam pad look good, shinny & centered. Some seem to not be perfectly straight; is it the result of poor lash pad contact? cam not fully broken in (engine is having 500 mi max since rebuild)? I'm not so concerned but I'll definitely keep an eye on them. One of them is having a contact pattern at rocker tip which is not symmetrical (pic #4). I think it is not normal so I'll get it modified also. Hopefully, grinding operation on rockers would not jeopardize lash pads dimension requirement. Each rocker is having one specific lash pad. For some reason, base diameter for every cam lobe is slightly different. Sourcing lash pads at correct thickness from where I am will be a never ended story This goes on Rebello cam with tight lash meant to be set at 0.005 at cam but adjusted at rockers tip at 0.008". Since I check cam clearance at rocker tip, looking at their shape explains why it was difficult to get consistent measurement & adjustments! Anyhow, I 'm good for a visit at my machine shop to check what they can do to help. Thanks also to Jim for his information, it helps to move forwards

I've wanted to do some as well on my car - just for fun. I've been looking a 70's race cars, they use brake duct over disk that surrounds the entire disk to enhance cooling efficiency. A little like what 1 Fast Z has done + proper disk covering. Which part also of the brake should be cooled the most? I see ducts going strait to the disks whereas it seems to me what we're trying to avoid is fading caused by too hot pads & fluid (in calipers). So I would try to orient air flow towards calipers. Regarding ducts on air dam, I come up with fiber glass units.

Good web shop to know! thanks for the tip! The ratcheting tool you're showing are for insulated connectors (the blue, red and yellow ones), you need one for non insulated connectors with a "W" shape in front of a "C" shape.

Jim, I remember your post. Your explanation is clear to me. I'll keep it in mind while I'll check my head. Thanks for your anwer I've read again the post (I was part of it - shame on me!) and it makes much more sense to me today!

Jim, do you have more info about the rocker grinding issue (or lack of)? I'd be curious to know more... Leon, Build is looking good. I'm following up this thread also

good point on leaks of course