Engine Rebuild Preparation

[cronoz78]

I have been told that the most experienced engine builders are on this forum so I thought I might get some help and direction.

I am considering doing an engine rebuild on the 78 280z this May.  It is only a street car, I drive in traffic and highway.  It is mostly stock except for Headers, Fujitsubo exhaust, ZX distributor.  I have had it for 8-9 yrs. 
The goal is a cost effective, reliable, healthy bump in power and fix leaking oil seals as the ODO says 27k. Now is that 127 or 227 miles??? 
I've done everything else myself but left the engine work to the last, now that I have time and space to mess around with it.

Reason: leaks from here and there, need fixing so why not just get it over with...
This will be my first engine rebuild (it doesn't look to difficult) 
Yes, I have the shop manual and the 2 books.

Does anyone have any suggestions on things I should change while I'm in there? (N47 head)

My loose plan:

- Do a leakdown, compression and dyno test so I can have a baseline.
- All Gaskets (Felpro full kit)
- Block to be decked/faced, honed and head to be decked/faced
- Cast Pistons - Flat tops any recommendations?
- Head rebuild?  decked/faced, ISKY 718147 Stage 1, ********What should I change here to accept the new cam? Springs?, lash pads?, retainers?, rockers?, shorter valve seals***** Recommendations?
- New bearings, rod bolts, frost plugs, timing chain kit.
- Ignition plan to keep the OEM (any benefit to a new ignition system?)
- ZX Turbo oil pump
- Adjustable fuel pressure regulator (suggestions?)
- While I'm at it... flywheel faced and new clutch OEM or Exedy OEM Replacement Clutch Kit 06009.  No lightwieght flywheel as I dont want a "blippy" thottle response.

Any info would be helpful if you have done this before 
Where should I buy these parts because there are good parts and CHEAP parts
If you don't feel like typing I can call you just PM me.

Thank you in advance.
D.

Edited March 28, 2019 by cronoz78

[S30Driver]

Get new Nissan head bolts (turbo if you find them),  OEM for front & rear seals, ITM pistons have a good reputation for your application,  new water pump, & liberal use  of assembly lube.  Zcar Depot is a good source for many of the needed parts.   Japan parts are always best vs china. 

Since you are in Canada, one of the northern experienced guys might be able to point you in the right direction for sourcing parts.

Nice looking 280 ....

[AK260]

^^^ wot he said ^^^

 

Let's not forget rockauto ;)

 

https://www.rockauto.com/

 

 

 

[rcb280z]

...and if you are going with a different cam you'll need an adjustable (program-able) fuel management system.

Edited March 28, 2019 by rcb280z

[siteunseen]

Tom Monroe's "How to rebuild your L series motor".  I'd never built a car motor, read that book about 4 times and now have a great running healthy 2.8 in my '77 280Z.  Easy to understand and everything is explained in simple terms which was great for me. 

https://www.amazon.com/Rebuild-Your-Nissan-Datsun-Engine-ebook/dp/B006VUICHG

[Av8ferg]

I’m looking forward to this thread. I’m about to do a full L-28 engine rebuild (my first ), so I’m interested in the same considerations. I’ve done some preliminary research and have read the first book “How To Rebuild Your Datsun Nissan OHC Engine”. Just bought the other book, “How to Modify Your Nissan Datsun OHC Engine”.

My thoughts here...BTW I’m no expert. Why waste time doing a leak down test before teardown. Compression test makes some sense but your be pulling the head anyway and you’ll find out quickly if you had a bad valve or leaking head gasket. Leak down would be if you hadn’t decided you were going to or needed a rebuild. Sounds like your moving forward regardless.
So my thoughts what’s the best bang for the buck after deciding what is the “End State”. You said a good street driver. With that in mind why would your replace the pistons to forged? That’s not going to make a performance difference unless you plan on boosting or really trying to make the engine high performance. Cams while able to increase power, reduce daily drivability and will require a change to the EFI to compensate.
From what I’ve read on the interweb here are some good options.
1. increase displacement. If you’re set on getting new pistons then bore out the cylinders. I’ve decided not to go this route. A good honing is my plan.
2. Porting the intake and head to smooth out airflow.
3. Header and exhaust. (You’ve done that)
4. Upgraded ignition.

Basics should do:
-rings, bearings, valves, all seals and gaskets, timing chain kit, new hardware. (Head bolts etc..).
-Good idea with turbo oil pump

Shaving the head to increase compression is good option but like any mod like that needs to be done with care. If you overdo the CR upwards to 10:1 your begin to experience possible pre-ignition which will not be healthy for your engine. Unless you live near an airport and want to use 100LL aviation gas. Be prepared to pay ~$8 a gallon.

For a basic rebuild, I priced all the parts and it was around $730.
This included all the items I put above in “basics should do” to include new freeze plugs, complete new engine hardware, and water pump.
I look forward to people who have more expertise to chime in and you’re in luck because this is where the L28 experts live.




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[cronoz78]

17 minutes ago, Av8ferg said:

The place I'm getting the dyno test I will get them to do the compression test and while I'm at it the leakdown I guess - that was my thinking
I will get cast 280zx flattop pistons to increase the compression. No need for forged as I will never turbo this car.
Regarding the cam. I have been in contact with a Z shop up here and they recommend the Isky Stage 1 as it enhances the existing power-band.  Nothing is drastic about it. This is their experience and I trust their input.
I don't plan on boring out the cylinders ect... I am trying to keep everything close to original so that the OEM ignition system can still be used. Basically, from what I understand the flattops and the new cam are the only things being changed from OEM and the adjustable fuel pressure regulator is the only thing that is needed to "keep-up."

 

 

 

I’m looking forward to this thread. I’m about to do a full L-28 engine rebuild (my first ), so I’m interested in the same considerations. I’ve done some preliminary research and have read the first book “How To Rebuild Your Datsun Nissan OHC Engine”. Just bought the other book, “How to Modify Your Nissan Datsun OHC Engine”.

My thoughts here...BTW I’m no expert. Why waste time doing a leak down test before teardown. Compression test makes some sense but your be pulling the head anyway and you’ll find out quickly if you had a bad valve or leaking head gasket. Leak down would be if you hadn’t decided you were going to or needed a rebuild. Sounds like your moving forward regardless.
So my thoughts what’s the best bang for the buck after deciding what is the “End State”. You said a good street driver. With that in mind why would your replace the pistons to forged? That’s not going to make a performance difference unless you plan on boosting or really trying to make the engine high performance. Cams while able to increase power, reduce daily drivability and will require a change to the EFI to compensate.
From what I’ve read on the interweb here are some good options.
1. increase displacement. If you’re set on getting new pistons then bore out the cylinders. I’ve decided not to go this route. A good honing is my plan.
2. Porting the intake and head to smooth out airflow.
3. Header and exhaust. (You’ve done that)
4. Upgraded ignition.

Basics should do:
-rings, bearings, valves, all seals and gaskets, timing chain kit, new hardware. (Head bolts etc..).
-Good idea with turbo oil pump

Shaving the head to increase compression is good option but like any mod like that needs to be done with care. If you overdo the CR upwards to 10:1 your begin to experience possible pre-ignition which will not be healthy for your engine. Unless you live near an airport and want to use 100LL aviation gas. Be prepared to pay ~$8 a gallon.

For a basic rebuild, I priced all the parts and it was around $730.
This included all the items I put above in “basics should do” to include new freeze plugs, complete new engine hardware, and water pump.
I look forward to people who have more expertise to chime in and you’re in luck because this is where the L28 experts live.




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[Av8ferg]

Do you know the compression ratio you’re going to get with an N47 head and flattop pistons, I’m just not sure what it would be? Looks like right now with dished pistons you would be 8.29:1.
I’m going to go with the P 79 head and flat top pistons.

Your chamber will be 9cc smaller than with the P79 and flat tops and that head has 8.82:1 CR.




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[Zed Head]

The ignition system can be used on anything.  It's the EFI system that will give problems.  You might be fine with your power increases, or you might find that it runs a little rich at the low end, or it pings at the high end.  Or it won't pass emissions.

The adjustable FPR is a crude way to add fuel at the higher RPM so that the cam has what it needs to make power.  But then you'll have to make adjustments to other parts at low RPM or you'll have a gassy smelling car.  That's the basic dilemma.  The EFI system has no O2 sensors so does not self-correct anything at all.  It's designed to produce a certain amount of power at each RPM range.  But it actually runs pretty rich at WOT, 27% extra fuel, so there's a little room there without doing too much.

[Zed Head]

And, this has come up before, piston choices are really limited these days.  Rockauto has one STD size piston available.  One piston.

https://www.rockauto.com/en/catalog/nissan,1978,280z,2.8l+l6,1209260,engine,piston,5620

Datsun Spirit sells custom pistons.

https://datsunspirit.com/shop/

[cronoz78]

Av8ferg - no I do not
Zed Head - good point i found this:
https://zcardepot.com/products/fuel-injection-retrofit-kit-fast-efi-280z-280zx

Totally out of the budget lol.

[Av8ferg]

Here’s a post on the topic from hybridz.

https://forums.hybridz.org/topic/70335-n47-head-on-a-flat-top-l28/


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