Building A L28 (Na)

[TheCrazySwede]

UPDATE: 2/14/15

 

After a rather long hiatus, the build returns with updates! As some of you may know, I decided to go with the professionals with this build. 

Looking at some local shops around my area, most notably Rebello Racing, and also some other shops across the country, I've decided to send my dear L28 out to Eiji Hosomi at Datsun Spirit Inc. (https://datsunspirit.com/)

 

There are three main goals that I wanted my motor to achieve.

1. Speed > Power. I want my motor to run like a hot knife through butter. It needs to be quick and very responsive. Power is nice, but a quick revving motor is what I seek.

 

2. Character. My beloved Z will eventually be my weekend car. I don't want the motor inside of it to just be a fast engine. It needs personality and character. Something that sets it apart from, let's say, a Honda Civic. This is why I went for triple Weber 45's, a flywheel that weights less than 10lbs, and my desired cam (more info on those later.) There's a certain character I want this motor to display, and I believe this build fits the bill just right.

 

3. Reliability. It might seem like an oxymoron, having a fast and reliable sports car motor, but I've seen time and time again how these motors, when built by true artists of their trade, can withstand almost anything you throw at them. My new motor will be running on pump gas, will idle smoothly and will barely break a sweat with the granny-like driving I put my Z through.

 

Engine Specs:

Bore/Stroke: 89mm/79mm

Pistons:  29mm Kameari (280g)

Rods: 139.5mm Kameari (~575g)

Crankshaft: Polished, Stock L28

Camshaft: .290 Duration / .490 Lift

Valves: New valves (stock size) Upgraded springs and retainers

CR: ~10.5 to 11:1

 

Now, time for some photographs!

 

Here's an album with all the photos I've gotten from Eiji thus far. I'll update it as the build continues:

http://imgur.com/a/Fyqtv

 

 

 

ORIGINAL POST:

 

Dear Forums,

I've been a long time lurker of these forums and of the community, but just recently, I've decided it was time I popped my Z cherry and got involved. I own a '77 280z (Motor has EFI; Transmission has 4 Gears)

I'm currently working on another L28 that I picked up (Carbed, N42 Head) along with a 5-Speed, but due to my lack of knowledge regarding these motors (We are a family of Ford Mustang owners) I seek your help in order to make sure this build isn't a total disaster.

To start off, hello; My name is Mike
I am 20 years old and I'm a computer tech. This is my first engine rebuild, so experience is not really something I have in my corner. Luckily, my brother and my dad are both mechanics, but they decided to pretty much leave me to learn how to swim in the ocean with this build.

My goals for this motor are pretty simple and straight forward, but I would still love to get some help from some of you more knowledgeable L-Series petrol heads.
Let me start by saying that I am not power hungry. We have the pony cars for that. What I want is a responsive motor, not a powerful one.

Engine Goals (Might get redefined as I learn more about these L-series motors)

1. I would like to hit 200HP at the crank (Although not necessary)
2. I want the motor to be naturally aspirated.
3. I love the look and sound of triple Weber carbs.
4. I don't think I need a stroker motor to produce a descent amount of power, so unless it's necessary, I'd rather not go there.

Things that I am considering (Please correct me if I'm wrong!)

1. Balancing the Crank
2. Lighter, flat-top pistons (I would like to keep the stock 86mm size)
3. Stock valves look good enough! Probably just stay with those.
4. I've read a few posts where people mentioned using L24 rods. Why is that? Weight?
5. A Mild performance Cam with upgraded springs.

As I mentioned above, I'm just learning about these motors, so your help is very much appreciated. I wouldn't know what to do without you guys. Also, I'm gonna post this thread over at HybridZ and see what those guys think. I'm gonna need all the knowledge I can get.

So that's pretty much it so far. Cheers guys, and thanks a lot for the help!
Not that it matters much, but here is the car: (It is currently undergoing bumper surgery!)


http://imagizer.imageshack.us/a/img716/8786/014wzu.jpg

Edited February 15, 2015 by TheCrazySwede

[siteunseen]

I held the flashlight for my Dad and fetched tools throughout my childhood. That was my mechanical education. I bought this book, How to Rebuild Your Nissan/Datsun OHC Engine: Covers L-Series Engines 4-Cylinder 1968-1978, 6-Cylinder 1970-1984: Tom Monroe: 9781931128032: Amazon.com: Books, and with the help of the good folks on this forum rebuilt a '77 motor, alone. Buy that book and don't worry about the crank, it's balanced already.

Great looking car too!

[HaZmatt]

Just out of curiosity, why dont you do a stroker?

[Diseazd]

http://www.classiczcars.com/forums/engine-drivetrain-s30/31001-new-l-28-goes-1970-a.html

[Diseazd]

http://www.classiczcars.com/forums/engine-drivetrain-s30/42488-new-engine.html

[Diseazd]

http://www.classiczcars.com/forums/engine-drivetrain-s30/34448-new-l-28-my-72-a.html

These should answer most of your questions.....N42 head doesn't need the head work that the P79/p90 heads need. I've had 0 problems with Isky cam/ spring combo. I've never done an N42/n47 head, so consult someone else for help there. Remember.....when putting performance higher lift cams.....1) use new rockers 2) use correct lash pads to center wipe pattern 3) use shorter valve seals if interference from retainer and valve seal is a problem. Have an expert check valve spring retainer to valve seal clearance.

Edited April 19, 2014 by Diseazd

[madkaw]

You might think about flat top pistons instead of the dished. Triple carbs or modified SU's will help reach your HP goal. There's no reason why you can't get 200 at the crank with modest upgrades. I think I have about 200 at the crank and it's fun.

Don't forget about gearing and trans to add to the fun

[TheCrazySwede]

You might think about flat top pistons instead of the dished. Triple carbs or modified SU's will help reach your HP goal. There's no reason why you can't get 200 at the crank with modest upgrades. I think I have about 200 at the crank and it's fun.

Don't forget about gearing and trans to add to the fun

Yup, flat tops and triple weber carbs are on my wish-list!

I've seen a few builds with L24 crank and rods, with flat tops from the L28ET. What's the reason for the L24 crank and rods? Is it the stroke ratio? I don't know what differences the ratio will give. If want a rev happy and responsive motor, would I benefit from the L24 crank and rod? Or should I be fine with my L28 equipment and just get the flat tops?

[Diseazd]

Your first motor.....go with what you've got....L28 crank and rods. Keep it simple and cheaper. Get someone who knows what he's doing (good machine shop or local Z nut) to put together bottom end and head. Assembly's not too hard after that if you read the FSM and follow tothe letter. SU's are much simpler than trips.....you can always add triples later. IMHO

Edited April 19, 2014 by Diseazd

[TheCrazySwede]

Thanks for the replies everyone.

I should note that I am in no rush with this motor, so I can take my sweet time learning everything I need to know before purchasing and swapping parts. That's why I wanted to consult you guys, first.

Your first motor.....go with what you've got....L28 crank and rods. Keep it simple and cheaper. Get someone who knows what he's doing (good machine shop or local Z nut) to put together bottom end and head. Assembly's not too hard after that if you read the FSM and follow tothe letter. SU's are much simpler than trips.....you can always add triples later. IMHO

Price for me isn't too big a factor. Money = Time. The more money I spend, the slower the build, haha.

A part of me doesn't necessarily want the simplicity. I already have an L28 in my 280z that pushes enough power (completely stock) to satisfy my needs. Want I want is a build that is different, behaves and acts different, from my original 280. That's why the idea of the L24 crank sounded intriguing. Wouldn't a setup like that alter the compression ratio dramatically? I may very well do what you suggested (Stay with the L28 parts) and move onward, but I don't want to brush off other build ideas only because this way was "easier." I want the build to be something I want, rather than something I had to go with, if that makes sense. I remember boring my 289 in one of our Mustangs and going with bigger pistons. I didn't really notice much of a difference, honestly. At least, not for how much money it required. I guess I wouldn't have much of a choice if I wanted the higher compression from the flat-top pistons.

[TheCrazySwede]

Again, thanks a lot, gentlemen, for your inputs and suggestions! It really means a lot. I'm glad there's such an awesome community available out there that allows us new-comers to pick up and learn the ropes.

Thanks guys!

[madkaw]

Keep what you got and get a lighter flywheel for quicker response . Add that to triples and lower gears=fun!

Seriously - most folks wouldn't be able to discern the difference in these engines(rod/stroke ratio), but a lightened flywheel would be more evident.

Go over to Hybridz and look for at thread 200rwhp and street able