L28 Rebuild Help For 1978 280z Honing vs Boring

[Racer X]

55 minutes ago, Ownallday said:

So more compression won't make any change power wise if I cant adjust afr?

There is more to this than just compression. Bore, stroke, cylinder head prep, camshaft lobe profile . . . . 

You can't go wrong by sticking with the same setup the engine had to begin with.

 

You're in California. There are a couple of knowledgeable and competent engine machine shops that are experienced with Datsun engines there. Rebello is the first that comes to mind. Also, the guys at Z Car Garage should be able to point you in the right direction. 

 

Edited June 23, 2023 by Racer X

[Ownallday]

1 hour ago, Zed Head said:

Similar conversations have happened over the last few years.  You better check parts availability before going too far.  Oversize pistons are not readily available.  You could end up with a freshly machined block but no parts to put in it.  Your engine will sit at a machine shop in out-of-stock parts jail, with a big bill waiting.

I see what looks like rust pitting in addition to scoring.  Looks like an expensive starting point.  Probably better off to find a different used engine.  They still pop up here and there.

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

 

Yeah I made sure pistons are which were my main concern are available. TopEndPerformance has 87mm forged pistons that can be made and rings are included. Main problem is forged pistons are overkill in my opinion and making the cost more than 1k. I went ahead and contacted three engines I see for sale, the blocks don't look promising though.

 

1 hour ago, Patcon said:

I agree with the others on the wall condition. Vertical lines would concern me. Possible ring scratches or skirt dragging. Also the mottling at the top of the cylinders concerns me. Not really sure what that is, possible corrosion damage?

I absolutely agree with Racer, that its hard to tell what the engine really needs with out Mic'ing it. Also be careful on grinding the crank. I had a hard time finding over sized bearings on a L20 build

After seeing everyone point it out, I see it better now, I though it was oil dripping. my nails are not able to dig into these lines however and feel very smooth. I am not exactly sure what it is either. It feels smooth to the touch.

thanks for the heads up, I will remove the pistons and crank next week. My co worker said he wants to hone it and see what the results are. 

1 hour ago, Zed Head said:

If it was my project I would put a list of parts needed together, with costs.  Add them all up and compare to what a good used engine will cost.  Evaluate against what your goals are.

I put a short list together of the various parts I bought for my car when I was getting it back in to shape and the final number was pretty big.  The small stuff adds up quick.

Here's the basic engine that you are starting with, for comparison.

https://www.ebay.com/itm/145108452163?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=743dF1EpST6&sssrc=2047675&ssuid=&widget_ver=artemis&media=COPY

 

I did do that, all the parts that I need not including new pistons is easily obtainable and not expensive. Once we add the pistons, it gets up there for me as $1000+ for pistons is a lot. All the engines for sale around me the outsides of the blocks do not look promising. The pistons seem to be the main thing holding me back from wanting to do a bore.

1 hour ago, Racer X said:

There is more to this than just compression. Bore, stroke, cylinder head prep, camshaft lobe profile . . . . 

You can't go wrong by sticking with the same setup the engine had to begin with.

 

You're in California. There are a couple of knowledgeable and competent engine machine shops that are experienced with Datsun engines there. Rebello is the first that comes to mind. Also, the guys at Z Car Garage should be able to point you in the right direction. 

 

You have a good point actually, I contacted one shop that does Z engines but they said they only build race engines. I have the same feeling that will be the same with Rebello which is actually out of reach for me anyways. They might as well be in another state with how far they are haha. I will contact Z car garage see if they can give me any insight if they are willing to.

[Zed Head]

Measurements after a hone should tell you something.  Does your friend have the tools to do proper measurements?

[Ownallday]

48 minutes ago, Zed Head said:

Measurements after a hone should tell you something.  Does your friend have the tools to do proper measurements?

He does not, but he can source them or I can bring it to a machine shop, either way I want to get the engine into a hot tank so it's going to a machine shop one way or another.

[Racer X]

Hot tanks don’t exist anymore, the solutions were hazardous waste. These days shops have a machine much like a dishwasher. Does the same thing, and is configured to filter the sludge and heavy metals to be removed for proper disposal.

Even if Rebello or the race engine shop that refuses to entertain doing work for you don’t do what you are looking for, they should be able to recommend a shop that will.

Also, you might consider a remanufactured exchange engine. Button your YouTube special back up, and order up a reman.

 

[Zed Head]

Actually, since it's open, some Scotchbrite, gasoline, and a rag will let you take the critical measurements.  I thought you were just going to break it down in a garage and run a ball hone through it. 

Why pay to get it hot-tanked if it's not what you want?  You'll be removing that protective film of oil and grime for when you put it in the back yard for storage.

Edited June 23, 2023 by Zed Head
it > if

[Patcon]

Zcar depot shows flat tops with valve relief. I don't know it those will play nice with the stock EFI. Maybe someone else can speak to that.

I would try to ask them if they can get a dished piston. You could probably also mill the flat tops some if you needed to to lower the compression. As long as you don't make the crowns too thin...

 

[Ownallday]

6 hours ago, Racer X said:

Hot tanks don’t exist anymore, the solutions were hazardous waste. These days shops have a machine much like a dishwasher. Does the same thing, and is configured to filter the sludge and heavy metals to be removed for proper disposal.

Even if Rebello or the race engine shop that refuses to entertain doing work for you don’t do what you are looking for, they should be able to recommend a shop that will.

Also, you might consider a remanufactured exchange engine. Button your YouTube special back up, and order up a reman.

 

Well, whatever method they use to clean blocks I want to have done. The original place I called TopEndPerformance actually led me to another shop but the guy I talked to said he wants to bore then hone too.

They have reman engines still? Where?

4 hours ago, Zed Head said:

Actually, since it's open, some Scotchbrite, gasoline, and a rag will let you take the critical measurements.  I thought you were just going to break it down in a garage and run a ball hone through it. 

Why pay to get it hot-tanked if it's not what you want?  You'll be removing that protective film of oil and grime for when you put it in the back yard for storage.

Not without doing measurements, I got the bearings out. It won't let me post the pictures with my phone but the main bearings are down to the copper while the connecting rod bearings look good. Almost no scoring on the crankshaft, very very minor a polish will clean it up nicely by the looks of it. Tomorrow I'm going to get thrust measurements before removing crank. The engine won't be sitting, either it'll get the work done with or without the bore unless I get lucky soon with another engine.

27 minutes ago, Patcon said:

Zcar depot shows flat tops with valve relief. I don't know it those will play nice with the stock EFI. Maybe someone else can speak to that.

I would try to ask them if they can get a dished piston. You could probably also mill the flat tops some if you needed to to lower the compression. As long as you don't make the crowns too thin...

 

That is for L24 and L26 I believe though as they don't show for 280z. I did contact MSA and they said they don't have anything. I'll try zcardepot next week.

That's not too bad of an idea, just would be scared on how much material can be removed from the top of the flattops and that would make the pistons weaker?

[Racer X]

1 hour ago, Patcon said:

 I don't know it those will play nice with the stock EFI. Maybe someone else can speak to that.

The method of getting the fuel/air mixture into the combustion chamber isn't relevant. What is important is that the quality, and the octane of the fuel/air mixture is correct for the application. If normally aspirated, a dished piston will only lower the compression ratio, and therefore the power output. If turbocharged, a dished piston would be more appropriate, as higher compression ratios don't work as well with forced induction.

 

1 hour ago, Patcon said:

I would try to ask them if they can get a dished piston. You could probably also mill the flat tops some if you needed to to lower the compression. As long as you don't make the crowns too thin...

 

Milling the tops of pistons that aren't designed and manufactured to be machined isn't a good idea. Custom made forged pistons are available with the potential for machining valve reliefs included in the design.

The dished pistons in this engine were used originally to lower compression and improve emissions at a time when manufacturers were under pressure to comply with the ever tightening emissions standards. Dished pistons were also used in the turbocharged L series engines used in the early 1980s Z cars.

 

[Racer X]

1 hour ago, Ownallday said:

They have reman engines still? Where?

There are a number of engine remanufacturers. Jasper is one that comes to mind. I believe someof the Z specialists also offer remanufactured engines.

 

1 hour ago, Ownallday said:

Not without doing measurements, I got the bearings out. It won't let me post the pictures with my phone but the main bearings are down to the copper while the connecting rod bearings look good. Almost no scoring on the crankshaft, very very minor a polish will clean it up nicely by the looks of it. 

This is sounding more and more like a very high mile engine that has not been properly maintained. I would bet that you will find excessive wear indicated by careful measurements. If it were mine, I would either go for a full rebuild, or an exchange reman.

Also, the cylinder block deck looks to be in poor shape, and will require a cleanup pass at the machine shop to ensure the head gasket won't leak. Have you checked it for flatness?

 

1 hour ago, Ownallday said:

That's not too bad of an idea, just would be scared on how much material can be removed from the top of the flattops and that would make the pistons weaker?

As I mentioned, machining stock pistons is not a good idea. 

Edited June 24, 2023 by Racer X

[dutchzcarguy]

16 hours ago, Patcon said:

Vertical lines would concern me

Ownallday wow! What a lot of responses! In just one day!  I agree with Patcon, those vertical lines don't look good.. You need a rebore (and a extra income.. maybe you can sell that coin collection) Also the worn bearings concern me.. 

If i tell you i haven't been on a vacation for the last 25 years.. (doesn't interest me i guess) Now you know where i get the money to restore some cars.. I always say: I'm on vacation when i'm behind the wheel of my own beautiful z(x) cars! 🤠

Maybe you could get yourself a good engine L24/L26/L28 with carbs (test it yourself, ask to do a compressiontest, if they wouldn't let you do it the engine is probably no good!)  There are a lot of ways that lead to your destination.. (I have seen engines cheap and you could take a look inside with a camera, those things are cheap (on your phone ones) endoscope.)

 

[Ownallday]

8 hours ago, Racer X said:

There are a number of engine remanufacturers. Jasper is one that comes to mind. I believe someof the Z specialists also offer remanufactured engines.

 

This is sounding more and more like a very high mile engine that has not been properly maintained. I would bet that you will find excessive wear indicated by careful measurements. If it were mine, I would either go for a full rebuild, or an exchange reman.

Also, the cylinder block deck looks to be in poor shape, and will require a cleanup pass at the machine shop to ensure the head gasket won't leak. Have you checked it for flatness?

 

As I mentioned, machining stock pistons is not a good idea. 

There is actually two Z specialty shops I will give em a call today if they are open otherwise I'll take a look at jasper too!

Yes, actually one of my other co workers stated it's a high mileage engine by the looks of it. I had another engine before this one and it looked a lot worse inside and was burning oil like no tomorrow. My co workers have the tools for the measurements, so either today or next week I will respond with some measurements of the crank. One person responded to me that is selling an engine too, going to look at it on Tuesday with an endoscope and see what the walls look like the the pics he took of the block does not look promising and he told me he had overheating issues and low compression from a blown head gasket.

I actually wanted to get the block decked. I wouldn't mind bumping compression closer to 9.1 if it wouldn't effect my chances of passing smog.

2 hours ago, dutchzcarguy said:

Ownallday wow! What a lot of responses! In just one day!  I agree with Patcon, those vertical lines don't look good.. You need a rebore (and a extra income.. maybe you can sell that coin collection) Also the worn bearings concern me.. 

If i tell you i haven't been on a vacation for the last 25 years.. (doesn't interest me i guess) Now you know where i get the money to restore some cars.. I always say: I'm on vacation when i'm behind the wheel of my own beautiful z(x) cars! 🤠

Maybe you could get yourself a good engine L24/L26/L28 with carbs (test it yourself, ask to do a compressiontest, if they wouldn't let you do it the engine is probably no good!)  There are a lot of ways that lead to your destination.. (I have seen engines cheap and you could take a look inside with a camera, those things are cheap (on your phone ones) endoscope.)

 

I know, very thankful for the responses and quick help with this. Taking everything into consideration and looking into possibly just getting the entire engine bored and machine if the measurements don't look good. However my co worker still wants to try an just hone the walls to see what the results are, he thinks the verticle lines are not a big deal because we can't feel them at all even with a very thing plastic gauge.

Haha, well my Z has been down for almost a year been saving up since then in hopes to get the car back on the road this year. I wish could say the same thing you do haha.

I'm actually going to look at an engine next week however the guy said he had overheating issues and a blown head gasket. For some reason he rebuilt the head but not the block, outside of the block doesn't look nice so gives me concerns the block is not good, but I will bring my endoscope to check.