Engine Rebuild

[HDAtom]

Hello everyone, first post!

I am starting a restoration of a 1977 280z. I am interested in doing as much as the project I can at home to learn as much as I can, even if quality does not come out perfect.

I am interested in rebuilding the L28 that came in my car, but I don't know the condition of it and what to really look for. The previous owner took a lot of necessary parts out like battery, fuel tank, and some other things, so I decided to just take it apart and try and figure out if anything is wrong inside the engine. I figured engines are simple (lol), fuel, air, and spark right?? It is already out and I can't do a compression test.  

I am trying to gauge the condition of my engine to see if this one is worth rebuilding. This is quite a black box build as the only thing I know about it is that it turns over by hand and the odometer is at 43k (I am assuming 143k). I think the carbon buildup is quite substantial and there seems to be some scoring marks, is this balancing or some other problem?

How does my engine look? What else should I post images of to see if the engine is alright? I know I have a lot to learn and will continue stripping the engine to look for problems, let me know if there is something I should look out for!

[grannyknot]

Yes it's worth rebuilding, if it is the original engine and you don't plan on putting something else in there.  Your cam looks like it has some scoring on a few of the lobes, closer pics would help.

143k is nothing for these engines, a compression test would have been helpful, if you haven't disassembled anymore then you could throw a starter on with a fresh battery and get some readings.  At a minimum it will need a refresh, gaskets, seals maybe rod and crank bearings.

Take lots of pics while you dismantle, bag and label everything.  The top of the head bolts are full to the brim with sludge so you can be pretty sure you are the first one to open it up.

Oh, and welcome to the forum, you found the right place.

Edited September 10, 2020 by grannyknot

[AK260]

On 9/10/2020 at 2:04 AM, grannyknot said:

Take lots of pics while you dismantle, bag and label everything.  The top of the head bolts are full to the brim with sludge so you can be pretty sure you are the first one to open it up.

 

 

 

Wot he said

 

That sludge also scoring suggests to me that the oil may not have been changed very often, BUT as grannyknot said, these are incredibly hardy engines.

 

The L28 is to some the best iteration of the L6 engine and has loads of room for performance upgrades, for more displacement, higher compression etc.

 

I second the idea of starter motor compression testing. But a part of me feels that if you have the time and inclination to open her up, you may as well do it properly and get rid of the sludge you can’t see.

 

Buy two books and study them well ...

 

 

How to Rebuild Your Nissan & Datsun Ohc Engine https://www.amazon.co.uk/dp/1931128030/ref=cm_sw_r_cp_api_i_rrCwFb4KTD7MQ

 

https://www.amazon.co.uk/Modify-Your-Nissan-Datsun-Engine-ebook/dp/B0092WMDCK/ref=nodl_

 

If you take the head off, you can measure the bores in several places and check if they are in spec. My 200k engine had the honing marks on the bores without any obvious signs of wear!

 

But if you are taking it apart, I would heed the advice given above with photos, bag and tag etc and also add that you may wish to consider a some mild modifications.

Edited November 10, 2020 by AK260

[HDAtom]

Thanks a lot for the replies, I really appreciate it!!

I will try and get some more closeup pictures tomorrow and share those.

I know this car has been sitting for at least 5 years and that was when the previous owner took it on as a project car (He didn't do anything to it though), so its probably been sitting for a long time. There was only about 1 qt of oil inside of it as well and it was crazy black. I was worried about putting any strain on it with the starter and cranking it, is thing something I shouldn't be worried about?

I am hoping to get the block inspected, hot dipped, bored, ect. I would like to add some displacement if possible and prep for higher HP in the future (maybe turbo? Still in the beginning stages of thinking). I know these engines have good forged guts. I have a lot of time to think and listen to books as I am sanding and painting the body first ?.

I have been taking tons of picture and have had a chest mounted gopro to make sure I can get it all back together...

I have taken off fuel rail, spark plugs, and other hoses since then, is it worth putting it back together to get that compression test? If I am planning and really messing this much with the block is it worth it to do a compression test?
 

[AK260]

I think you have the right idea rebuilding.

 

Now then, beware that the whole modification thing; it is a rabbit hole and can very quickly get very expensive.

 

The question you have to ask yourself is, do I feel lucky? Well do ya? But seriously the question is: what it the car going to be and how you will want to use it. No good having all that power with a turbo if you can’t put it down. So plan the car as a system. Some people get excited by what looks great on the internet and end up with something that just doesn’t work well together.

 

Some easy mods that don’t cost a lot and give the best BHP/$ are a sensible overbore, properly gapped rings, flat top pistons, a shave of the head, porting the head, a fast road higher than stock lift cam, better valve springs and seats and an appropriately sized exhaust manifold (header) and free flowing system (bigger is definitely not better here, it has to match the gas flow and the ports). Oh and decent ignition and fuelling. The power in these cars is made in the head, so focus your efforts there. However one of the things that makes my engine great is the attention to detail of the engine builder. Each cyl was bored to the exact dimensions of each piston and rings. The rings were gapped to perfection and so and so on.

 

It’s easy to get carried away with big duration lumpy cams etc. For example you don’t necessarily need forged pistons and rods to make good power in an NA road car, but if you like the bragging rights and have the money to throw at it then go for it.

 

My NA L28 on 240 SUs, cast flat top pistons with +1mm, is doing a shade over 240 BHP at the flywheel so roughly around 190-200 at the wheels. But that is a little irrelevant as peak torque of c. 210lbft arrives at 5k rpm - so while I can light up the 195 section rear tyres in 1st if I wanted to, the power is progressive and builds nicely the harder you go, so I don’t really need an LSD diff or big wheels / tyres with coilovers etc. But a stroker or turbo engine would be shredding those tyres all day long and will need significant spend on suspension, diff, wheels / tyres etc.

 

My engine pulls very hard from 3.5k to 7k RPM if I let it go that far and can pull nicely all day from 1.5k around town and in traffic. But some prefer less revs and more torque lower down so they build a stroker or go for a different cam etc. What is your driving style? What do you want out of the car? Will you drive fast twisty roads where you sit between 3k - 5k rpm for most of the time and like to cruise in towns or are you a racer who needs power at the top end? My engine cost £2.5k sterling to build - I got a superb deal, then I spent another £1.5k on stuff around the engine like light weight flywheel, electronic ignition, crank damper etc. If i want to get to 300bhp NA I have to quadruple that budget. If you go turbo, depending on how hard you hit it, you’re in for forged pistons and rods which immediately adds another £1k-£2k, better bearings, etc etc.

 

So in short, what I’m trying to get at is, take your time, do some serious thinking about what you want the whole car to be, do homework on your options within your budget and build a well executed engine that suits: the car, your driving style and your budget. Then add 50% to your budget unless you can exercise soldierly self restraint.

 

Don’t get carried away by the internet mechanics, big talk / big numbers and fancy kit which you can throw a lot of money at for small gains. But most important of all is to do it right and only once!!!!

 

Many people talk horsepower at the bar but in the real world, behind the wheel we all enjoy driving a decent torque curve.

Edited November 10, 2020 by AK260

[grannyknot]

You don't need a fuel rail or spark plugs to do a comp. test, just a starter. In your case a comp. test and and or leakdown test would just tell you where a problem lies before you open it up but if you're going to tear her down any way then just make sure your measurements are accurate.

Some specialized tools are needed to properly measure the bores and journals so check into the cost and use of them before you commit to doing that yourself.  Those two books will answer most of your questions and give you a very good idea of what you're getting into.

[Reptoid Overlords]

You will need to look into programmable EFI if switching to anything bigger than a stock cam.  At least that's the way I understand it.

[Dave WM]

ditto on the leak down test will tell you a lot about the engine.

I built an engine test stand, just to run the engine. I like to base line things before tearing into them, that way I know at least what I have got.

 

[Dave WM]

here it is on the test stand

 

[HDAtom]

I am absolutely blown away by the responses! Haven't posted on too many forums but I usually get blasted on the first post no matter where it is.

 

6 hours ago, AK260 said:

Now then, beware that the whole modification thing; it is a rabbit hole and can very quickly get very expensive.

 

I looked a lot more into things last night and wow do parts get expensive! Not to mention machining and other things. I think I am going to cool it on my thinking about hp, I know these cars are light and do well with "lower" hp numbers.

 

7 hours ago, AK260 said:

The question you have to ask yourself is, do I feel lucky? Well do ya?

I am NEVER lucky....

 

6 hours ago, AK260 said:

So in short, what I’m trying to get at is, take your time, do some serious thinking about what you want the whole car to be, do homework on your options within your budget and build a well executed engine that suits: the car, your driving style and your budget. Then add 50% to your budget unless you can exercise soldierly self restraint.

I usually approach car stuff with a take it apart now and then price as I go, but I see with the engine I REALLY need to make a spreadsheet and plan for everything I am going to do and then execute later. As well as adding 50% to that and then probably spending double lol.

 

6 hours ago, AK260 said:

Many people talk horsepower at the bar but in the real world, behind the wheel we all enjoy driving a decent torque curve.

 

I agree! 

 

4 hours ago, grannyknot said:

You don't need a fuel rail or spark plugs to do a comp. test, just a starter. In your case a comp. test and and or leakdown test would just tell you where a problem lies before you open it up but if you're going to tear her down any way then just make sure your measurements are accurate.

 

Alright, next step will be getting it ready for a compression test and hopefully leakdown as well.

 

1 hour ago, Dave WM said:

I built an engine test stand, just to run the engine. I like to base line things before tearing into them, that way I know at least what I have got

That is an awesome stand, loved the videos, I may be interested to do it!

So much more to think about......


In terms of my plans for the car, this list also goes in order of operations. I hope to finish the car with about 15-20k. This leaves about 3 or 4k for the engine, power is not my main concern atm and can be revisited later as I know these cars are fun stock and its simple enough to pull the engine and really get it done if I choose to in the future. I prefer suspension and tires over power as there are a lot of fun curvy roads out here and I don't like speeding tickets... Everything in this list is fully DIY except for the engine.

• Got the car for $1,000
• Currently fixing body (its not too bad, almost all the usually non-structural rust spots) for hopefully ~$500-1,000
• Painting at home for ~$2,000 (already priced out liquids and know where I am buying it) lets hope I can do it well ?
• Fix engine... ???$
• New wiring harness - ~$400 (I'm actually excited for building this, thinking about templating and trying to sell some to earn little bit of cash for the build as well as helping other with a high quality harness)
• Rebuild transmission - ~$500 (hopefully)
• Rebuild differential, maybe OBX LSD - $500-1,000 
• Hoping for a full Techno Toy build as almost everything under the car looks shot and I hate money. $8,000-10,000
• Interior - ~$1000

This is quite an ambitious project, but I have about 3 months till my next job starts and look forward to putting 40-60 hour weeks into this. Please let me know if my plan is dumb lol. I look forward to asking for lots of help and learning a lot...?

 

[AZDatsun]

You want all that done in 3 months? If so that’s probably not going to happen unless you know all the parts you need up front and order it all now, between shipping, taking things apart, putting the new stuff on, then more shipping because you forgot little things that’s not going to happen. Don’t want to be a Debby downer but that’s very ambitious for a single person and not a full time resto shop that can work in multiple areas at one time


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[siteunseen]

I rebuilt a '77 about 8 years ago. The Tom Monroe book AK260 mentioned is the first money you should spend in my opinion. Read it a couple of times then start the work. 

Bag and tag is the next best advice. I can add my experience with that too, write the description on a piece of paper and put it inside the bag. A sharpie on the outside will smear and rub off after being handled a few times. Buy a gallon of lacquer thinner for cleaning and soaking parts as you remove them. A couple of 5 gallon buckets with the lids will be useful too. Brass wire "toothbrushes" work great with the thinner.

I could go on and on but like Grannyknot says "you found the right place". There's always someone on here to answer any questions or offer advice from experience.

Here's a couple of the most helpful things I've read on the internet. The tech tips from 240260280 is a money saver. He also has a '77 so it'll be extra nice.

http://www.atlanticz.ca/zclub/techtips/

https://www.datsunzgarage.us/

Oh yeah! The forum has a lot of info too. 

https://www.classiczcars.com/forums/forum/184-build-threads/

 

Edited September 10, 2020 by siteunseen