Zed Head

I wanted to separate the "upgrade your wiring harness if you upgrade your alternator" issue out completely from the discussion. It comes up a lot and it kind of jumps in to people's thought process, and kind of makes sense. Basically confusing voltage with current/amps. The alternator is irrelevant to burning wires unless it shorts out. Even then it's the battery doing the damage. Many people probably add all of the extra loads at the same time they add a higher capacity alternator. Then when wires melt or fuses blow they blame the alternator instead of the loads. There's the whole other side discussion also about alternator idle speed supply versus maximum possible. Another important detail that gets overlooked. Kind of like peak horsepower versus usable horsepower, or power under the curve. Details. I bumped my idle speed up about 100 RPM and made things a lot better.

A point of reference that could help people mentally get hold of the capacity, or supply, versus load, or draw, difference - a typical battery has 500 - 600 amps available at an instant. CCA. That's why when you connect a wire wrong, and create a low resistance path to ground, or high draw, you can vaporize a wire in a flash. In other words, we all have a 500+ amp power source sitting in the engine bay right now, that dwarfs any alternator you could find.. So it's not the supply side that matters, it's the draw side, Any discussion about wiring harness weakness should really never even mention the alternator. The battery power will do the damage.

That's often from running lean. If you wanted to get tricky you could disconnect the coolant temperature sensor, either at the sensor itself or unplug one of the bullet connectors in the harness over the manifold. That will make it super-rich but it might run right for a while until it gets warm. A clue. You can get fouled plugs from lean misfires. You're kind of in a search for cause/effect right now. If you can make something change reproducibly it will give you a direction to go in.

Are you positive that your plug wires are installed correctly? 153624 counterclockwise. The engine will start and run with them installed clockwise. Strange but true. Backfiring is usually caused by spark happening at the wrong time or lean fuel-air mixture. I've seen bad front-fires from exhaust valves staying closed due to bad cam lobes. Is it popping through the intake manifold or out the tail-pipe? Easy to get back and front mixed, description-wise.

JSM asked a good question. Can you keep the engine running at all, or are you focusing on just idling? Not clear if it's a running problem, or and idling problem. Also can't tell if it backfires just once then everything is okay, or if it backfires once every time you rev it. And is this when it's cold, or when it's hot, or both? Seems like you're making progress. Have you had it out for a drive yet? Maybe it needs a slight thrashing.

If you called MSA and asked nice you might get somebody to pull a part off the shelf and measure it. I put your intake number in MSA's search box and this came up. Even though it's not actually in the visible text. So it's in their database somewhere. They can find it, but will they measure it for you? Since it's just going to be the same numbers that are in the FSM. Good luck. http://www.thezstore.com/page/TZS/PROD/10-5001 http://www.thezstore.com/store/merchant.mvc?Screen=SRCHM

Actually I think with good contact made the current wouldn't jump a decent-sized gap. Look at how an over-gapped plug can cause misfires. You have to leave some work for the doer, once you supply the idea. There are also solid-state switches, which don't use gaps. I know that they exist but I don't know much about them. Or the dielectric filled type, used to be PCB's, don't know what they use now, probably silicone fluid. Personally, I'd just find a different way. The question is interesting to discuss though. I had a reason to go browse around high voltage switches. http://www.behlke.com/separations/separation_b1.htm and dielectric fluids https://en.wikipedia.org/wiki/Liquid_dielectric How about killing the points ground or ignition module side? The negative side of the coil, instead of positive. Or the trigger circuit for electronic? No circuit breakage, no magnetic field collapsing, no spark happening. A switch on the wires (green or red) to the module from the variable reluctor maybe. That would work and the common thief would have no clue where to look. Or isolate the distributor body and use a dedicated ground wire, with a switch in it, for points. You can supply all the power you want, but if the coil current doesn't make and break, you get no spark. Just brainstorming now...

The dimensions are also in the FSM's, by car and year. Same info that site provided though. How many people are going to have some valves, out of the head and available to measure, for which they know the part numbers? Google says that they might not be 240Z valves though - https://www.nissanpartsdeal.com/parts/nissan-valve-intake~13201-a1100.html and https://www.nissanpartsdeal.com/parts/nissan-valve-exh~13202-n0401.html You might find the FSM's at http://www.nicoclub.com/datsun-service-manuals

With a solid path to ground through the switch, you'd end up with two possible low resistance paths, one to the distributor or one directly to ground. So the gap would easily be jumped only if the easy path to ground wasn't there. Right? That's where I ended up. The same thought did enter my mind though. But I kicked it out

To be clear - I went in to detail because Takhli writes like he would want to discuss these things. If you're going to describe how you finessed a a part down to 0.0005" precision you should be happy that there's someone out that can appreciate it. That's a measurement that will change if you breathe on it. It's surprising that he wouldn't appreciate the suggestion of granite surface plate. The proper responsive would have been "I wish I had one of those". The response that came instead makes one wonder. That's what these forums are for. To discuss these things and learn some new things. Alright. Moving on now.

I made a point. I'll stay out now. Always disappointing that people can't engage in a simple adult conversation though. Makes me feel alone. People are so sensitive about their reputations these days, with likes and follows and reputation scores. Happy happy joy joy only. No critical thinking allowed (as opposed to criticism - they're not the same thing). Like my opinion even matters that mcuh. We could have had a really interesting side conversation about measurement techniques and their importance to high-quality engine building,. Instead we're talking about a guy's epoxy-coated door work bench, as opposed to a solid granite work surface. The heart of this thread is about expertise and we had a chance to talk about it. But it won't happen now. Your guy will probably get your engine working just fine. Enjoy it.

I think that several guys from CZCC were out there a while ago and ran through the EFI tests at the ECU connector. That's the place to start, the ECU connector, I'd say. Then dig deeper if the numbers are off. Still, Jai said that she never changed the plugs after the ECU replacement. So the earlier suggestion of a complete tune-up before getting carried away still seems reasonable.

Arcing, or discharging to ground, from the coil won't hurt it. You could make a T off of the center wire that runs to a switched ground. Close the switch and coil discharge just goes directly to ground. Open it and it passes to the distributor.

You're trying to defend the indefensible. You said you used a board as your flat surface. That's your error. And you haven't shown that you achieved any precision. You said they were good but didn't show anything. More detail about the process doesn't mean more accuracy. And you didn't even recognize the Starrett surface plate. People get confused on measurement principles all the time. I still do and I've studied them. Wanting to be an expert and actually being one aren't the same thing. Sorry. Looks like fun, but you're really just a guy with some tools and a nice project. Let's see how the engine does when it's done. No need to get defensive, just say "thanks" and carry on. Not trying to get in a pissing match. You're writing like you're an established expert but it really seems like you're just working out of Tom Monroe's book.

Have you seen that Fast N' Loud program where they used the cheap oil and the zinc additive? It cost them a motor. Made entertaining TV though. For all of the money you're spending on the engine parts, why take a chance? Use a high-quality proven oil with zinc already added, designed for breaking in these types of engines, I'd say. There's no magic blend you can make yourself that will be better. And it's not "synthetic" that matters, it's the zinc. To be clear. You haven't described your valve train pieces. That's where the problems happen. Cam lobes and rocker arms. Make sure that those are right, otherwise the oil used won't matter. People still wipe cam lobes with good oil, but bad parts.

Good luck. I'd put the car together and give it a drive before buying any engines. The little L6 can make plenty of power. The 280Z 2.8 liter engine is 1/3 bigger than what you had. If I read the pictures right, it's an automatic? You could add clutch pedal and gear to your to-dream list. You'll need that for whatever engine. I just spend a week encased in snowy roads here in Oregon so I understand the need to dream. I don't know how you guys survive (mentally) up there.

He might be suggesting what he showed in the picture. Starrett makes high precision measuring tools. http://www.starrett.com/ (Grammar note - Starrett uses "precision" imprecisely in their web page. Word nerd) Wood is compressible, and flexible, and absorbs moisture and other liquids. The moist side will expand, causing a bow. Pressure will bend it slightly. Even a piece of glass will bend. I think that if you swapped "flat enough" or very flat for "dead flat" you'd be okay. You still wouldn't "know" though. Unless you checked with some Starrett measuring tools.

Indeed.... Those are both expensive starting points, in general. But they make power. So your plan is to build a hot-rod Z? Drag-racing? The 5.3 alone gives a super power-to-weight ratio. The turbo would make it ridiculous. What's your plans?

One last chime - I have a 280Z with big bumpers so my measurement will be farther from the body than a 240Z.

Wait. My other answer was not "literal". The answer, where the tip ends, is 3/4". But wait...a re-read has me thinking that I can't give an answer. The "tip" by definition does not "exit". It's just the tip. I think the question assumes a round, square-cut end. So mine doesn't fit the question. Good luck!

You're right CO. Here's a direct, literal answer from me. - 1 7/8". That's a negative sign. Where the exit hole begins.

Is the connector different than the Z car connector? Not a T plug? Still not clear. Is it an adapter or is it a plug that needs to be wired up? Just trying to help out. You didn't really answer any questions. No offense. It's looking like a late Maxima alternator with a pulley swap, that doesn't use a T plug. @zcardepot.com

Z Car Depot should really have more wiring info on that page. I'm sure that they're missing sales because of non-clarity about one of the most confusing parts of the alternator swaps. You'd need one of Dave Irwin's (or MSA's) adapters for your 240Z, since yours came with an external regulator. @zcardepot.com

The questions are answered on the web page. No core charge. Cases cut to fit. Belt info supplied with the belt so that you can replace it in the future. He wires the Sense and Lamp wire directly to the charging wire. So you'll lose your Charge warning lamp (described on the page). It's basically a bare-bones primitive charging system, with high capacity. A person could probably wire it up to work correctly and still get the high capacity. He's both reducing and increasing the value of the product, one by losing the Charge lamp and adding the special belt, and the other by making it almost fool-proof to install. The belt is probably necessary for the same reason that manufacturers went to the multi-groove belts. It takes more torque to spin the little pulley when it's putting out the high amps.

Don't forget direction. I have one that curves slightly downward. It blows the dust off the road when I hit the gas. And think about bumper style, if you have one. I don't think that just length is going to be the full solution. (This post has some unintentional double entendres, I know...).