Zed Head

Actually the early 5 speeds are the one with the gap between 2nd and 3rd. The later "close ratio" boxes are well spaced. I've used a 3.54 behind a close ratio with the tall first gear. It just takes more attention to the clutch. If you live on flat land it won't be a big deal. If you live around some hills you'll put extra work in to your starts from a stop sometimes. Don't overlook tire size in your calculations. And, like Dave said, you might find that 5th never gets used. Why do you think 5th is "short". Does the engine get buzzy? I found that once I got my engine squared away, cruising at high RPM was much nicer. An unbalanced engine is annoying.

Don't forget that you'll need to have the 71B case machined to fit the 71C oarts, in order to use a 71C on an L6 engine. Also, the 71C 3rd gear is probably the same as your 71B third gear if it's an early 71C So, really, the fastest way to get back on the road is to just swap in a used 3rd gear. There is little strength benefit to the 71C unless it is a late 90's 71C with the wider gears.

Seems like you still have a problem. You tried a new gauge and still got low pressure. But the engine is running rich with 190cc injectors. Something is causing the injectors to stay open too long, Could be the AFM, the ECU, one of the temperature sensors, who knows. At least you know which parts are good though, so you can focus on the the other possibilities.

People use "short" and "tall" differently and many use them incorrectly. Not sure what you mean by short. A 3.54 will give you the "tallest" 5th you can get with any transmission, unless you find a 3.36 diff. If you install a 3.9 5th will get shorter. I'm using tall and short as I understand them Tall is lower RPM, short is higher RPM, or faster acceleration. With short you run out of RPM sooner. There are only three 5th gear ratios available. 80-81 is in between the other two. After 81 gives you the lowest cruising RPM. "Tallest" 5th.

There are fairly simple things that people do for minor improvements. Paint the inside of the block with glyptal to seal it and any casting sand that might still be there, and for quicker oil drainback (after you have it hot-tanked). Clean up the coolant passages of casting flash with a grinder (before you have it hot-tanked). Apparently there can be quite a bit. Smooth the crankshaft weights so they don't hang on to oil. Balance things, generally. The "How to Modify" book is worth a look for ideas. Since you have time.

21 and 26 here show a difference. Nissan calls both "flywheel"s and considers them part of the crankshaft. http://www.carpartsmanual.com/datsun/Z-1969-1978/engine-280z/piston-crankshaft

All I hear is an engine that seems to be at high RPM, but I'm on a computer with bad speakers. A "chime" is like the noise a wind chime makes when the wind blows. Dainty. Didn't hear that. What is the idle speed RPM?

Your engine is looking more and more like just a high miles engine. That glued on badge is an odd thing now. Aftermarket sprockets only have to match the tooth pattern and shape. They're not rebuilt like alternators, they are brand-new parts, but made from the aftermarket manufacturers' tooling. Look for a good brand name. Cloyes seems to be well known in timing sprockets and chains. Often you'll find the same exact part for different prices from different suppliers. Sometimes there's only one company making a part so you might as well just buy the cheapest, unless there's a warranty.

Are you using copper tube from the pump to the carbs? That's interesting. The tube looks of small diameter. Is it a new thing or has it been running fine like that? There's not much to gauge placement. The fitting needs to be between the pump and the carbs. Describe a gremlin and you'll get more ideas.

My 81 engine had steel gusset brackets. I've read that they were for NVH reduction. If you look at the engine-transmission assembly from the side you can see that there's some leverage there. There's a lot of weight hanging under the last bolts in the engine, without those brackets.

Aluminum usually cracks as it bends. You probably have the mounting surface machined to run true to the tire surface by a good machine shop. Probably expensive to do though.

I had a warranty just like that so I hooked up my spare EFI system to make sure it ran right. You'll be well past 30 days by the time it runs so really you don't have a warranty. Probably fine, they're tough engines. I was just trying to get a feel for how detailed your plan is. You could run a carb and go crazy and have more flexibility.

Just to fill out the possibilities - you don't have to remove the head to replace the timing chain and sprocket. On the other hand, the chain and sprocket might have been replaced when the head was rebuilt, so the head might have that amount of wear. And, to speedroo's point, a counterpoint - don't assume that you can do the best job possible. Really, just do the cost/benefit analysis and be aware of the rabbit holes...

The notch and groove are a better measurement of chain wear than the finger test. Even looking at how far the tensioner is extended will tell you more I think. As far as performance improvements you probably want to consider your engine management system. The stock EFI system is designed to work with a specific engine. These aren't like the old carb'ed engines where you just bump up the compression, put a cam in it and some headers and you're done. You might get more power with some bolt-on mods but it will run like crap for daily driving. I like a full plan myself, but doing things on the fly is still fun.

It's already broken in. I'd just fill it with the oil you intend to use and go right to whatever oil change schedule you normally follow. The only new wear surfaces are the valve ends and the lash pads and they don't see the same sliding wear that the cam lobes do. One opinion..

They're all good. Although I was actually hoping for clouds the other day. too much UV for me. To Av, it's easier to evaluate somethings when the engine is assembled. If you want to keep the unworn parts. If you're just replacing all of the wear parts then it doesn't matter as much. You can drill two holes in a piece of flat steel bar and bolt it to the crankshaft to lock it down, for removing the various bolts.

Nothing wrong with that. The notch and groove is what Nissan created so that you could evaluate chain wear.

Somebody must have modified the Nissan rebuild then. Not arguing, just pointing out that the "M"N47 head is designed for the Maxima L24E engine, Nissan did not put them on L28's. . You have a rebuilt short block with a different head on it. Or, you actually have a Maxima L24E engine, not a 280ZX engine. Does it have L28 stamped by the 5 and 6 plugs, on the block. It would also be nice to start your own thread instead of filling up madkaw's build thread. Here's the thread where CO talks about CR's.

Are you sure that your heat gun isn't catching some of the head and it's cooling passages? The FPR would have a steady flow through it, it doesn't pulse like the thermostat does. The thermostat has a chunk of wax in it that melts and solidifies over and over. That's why it pulses. The FPR has a spring and a diaphragm that just move based on vacuum and fuel pump pressure. If you put a piece of cardboard behind the rail and measure again it might stop pulsing. If it does pulse it seems more like a fuel pump thing, with the flow rate changing. Maybe a voltage pulsing causing the fuel pump to pulse. Who knows it might actually go all the way back to your alternator/regulator. Maybe it's dying or engine RPM has it on edge.

So the question might be are you rebuilding it for fun or to make it better? I'd at least check valve lash and the cam sprocket notch and groove, just to see what the wear is on the valve train. If it's freshly refreshed you'd be wasting money to mess with it. The cam lobes look new. It might end up in worse shape when you're done, no offense. Sorry to the guys looking for internet entertainment. I'm one of them...

164k is not a ton of miles. Normally a person would measure pressure, do a leakdown test, look at oil consumption, check the cam sprocket notch and groove, etc, You're kind of jumping ahead Av.

The P79 and P90 heads have the temperature sensor in the head also. What is cast in to the head up by the 1 and 2 spark plugs? It's probably a P79. Nissan would not put the L24 head on an L28. You can use the various calculators to estimate CR. Plus there's another thread by CO discussing the topic.

Did the car have 164K or the engine. That emblem glued on to the engine is not a Nissan factory thing. It looks like it's a fairly fresh reman. You might find that everything is almost new. Might be ready to go as-is. Stop and think. Someone ot there has probably seen this before. @240260280z

It's over 9 MB also. Pretty bulky.

A YouTube link would be better. Microsoft's trying to get my credit card number...