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L28 Rebuild


C.A.R.

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CAF-final.thumb.jpg.2ada405c3e99b9f4796c502e6c44c27d.jpg

I thought the community might be interested in an L28 I’m rebuilding for a 240Z that belongs to a customer of mine.

I’ve been asked to supply and rebuild a L28, and include some minor performance upgrades where possible, with a modest budget of $6,000.

As the cost of triple side-draft carburettors is not in the budget, I can’t go too crazy with lots of performance modifications.
The owner – by his own admission – is more of a ‘cruiser’ than ‘boy racer’, and therefore the 240Z will retain its original twin Hitachi’s, along with it’s HM Headers and a 2.5 inch exhaust.
Therefore compression is going to be set around 9.0:1 Static, so it won’t get close enough to be able to detonate (ping).
No ‘hot’ camshaft either, as it will simply make it a pig to drive with a narrow power band, dictated by the twin Hitachi’s not being able to supply enough air.
I am however fitting a Performance Ignition (Scorcher) distributor as I suspect the current 280ZX electronic item fitted currently is worn out and causing running issues.

Les at LCR has been gracious enough to allow me to build this engine at his shop, to use his VAST wisdom in L-series engine building, to-wit I am VERY grateful to him.

Specs are:

L28 (F54) block, bored to 87mm.
Prepped Std stroke crank.
Std con-rods
New 87mm dished pistons with cast rings.
Reconditioned N42 cylinder head.

Clive (Wade) 733a camshaft (very mild).
Performance Ignition (Scorcher) distributor.
New timing chain & guides.
New Std oil pump.
NDC bearings.

Payen gaskets kit.

So, on with the build!

The block:
I actually purchased it as a complete motor, hoping it'd take a 89mm bore for my new L33 build but sadly it was only good to 88mm. 
It's a late F54 casting, that had done a lot of kms & had a rather large lips at the tops of it's bores - which were too large to hone out, so it had to be bored to 87mm.

 

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As you can see I'd already started to strip it down when I took the photo, hence removal of the cylinder head.
First step is to check the top of the deck for major cracks - it was crack free, so on I progressed.

Next the rest of the short motor is pulled down: timing case, chain & guides. Then the rods & pistons are extracted, the crank is removed & the Welch/Freeze/Core plugs knocked out.

post-100072-0-21046100-1503269875_thumb.jpg

Next step is to remove the Oil Pressure relief valve by punching out the ball & extracting the sleeve by turning in a 3/8 tap:

post-100072-0-36928400-1503269933_thumb.jpg

Ta-Da!

post-100072-0-05198600-1503269969_thumb.jpg

Next up I removed the gallery plugs at each end of the block.
This is done so the crud that collects in the ends of the oil galleries can be removed.
If this isn't done the crud WILL dislodge, & go through the bearings & bores damaging both when the freshly rebuilt motor is started for the fist time...
The centre of the steel plug is centre popped and then drilled to 5mm, then tapped to M6. 

post-100072-0-49634700-1503270282_thumb.jpg

 

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I then used Les's special works plug remover to extract the plug, but if you are doing this at home, you can just use a LARGE nut & couple of M6 penny washers & a suitably long enough M6 bolt to get the plug out.

 

post-100072-0-50934800-1503270055_thumb.jpg

 

Rear plug:
 

post-100072-0-16857900-1503270019_thumb.jpg

 

post-100072-0-99270900-1503270041_thumb.jpg

 

After this it was given another visual inspection, sonic tested & then taken to the engine shop to be hot-tanked, bored & decked.

While that was going on, I started prepping the crank.
The journals were checked by Les for condition & then measured with a micrometer to make sure they were round within a few tenths of a thousands of an inch.

It was pronounced fit for use, so then the core plugs in the crank journals have to be removed for the same reasons as stated above.
The trick is to carefully centre-pop the plug, then drill a hole into it the right size for a self tapper to be screwed in.

IMG_20151207_095319_617_zpsncshhcjd.jpg

With the self tapper screwed in, a claw hammer is used to leaver out the plug like so:

IMG_20151207_095508_533_zpswvtzq6n7.jpg

With all 6 plugs removed I, tapped the holes to 5/16 UNC so grub screws can be fitted in place of the pressed in plugs.

 

IMG_20151207_101931_543_zpsyknoytkq.jpg

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I then took it around to the engine shop to be hot tanked & the journals given a good polish.
Indecently the engine shop reported that it had a small 4 though bend in it, but they were able to peen it straight for me.

To be continued...



 

Edited by C.A.F.
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The screw plugs in the crank, a positive retention method, ie centrepunch edge f thread/crank metal ?

No. Because they'd never be able to be removed again if they were staked. Doing them up tightly will be fine.

 

Rather than stock rods, why nt 240Z or 1& 1/2 L16's worth f 133 rods, and some flattops?

That will liven it up a touch!

Clearly you haven't read my post accurately mate...

 

For pistons, look at the 87.5 Isuzu G200 units, they suit the longer rod, will poke out the blck a bit, ( mill down to suit) and are an affordable cast type piston.

No. Because it'll have to much static CR with the N42 head, the twin Hitachi's & it'll detonate.

New .040 over dished pistons with cast rings were less than $500, so why would I go to the expense of fitting Isuzu items? 

It's a NOT a race car Jason!

Edited by Lurch ™
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Hi Mate

 

Looking forward to following this build. I have being waiting for someone to post a build in this budget range.

 

Cheers

PB

Edited by PB260Z
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Should we run a pool on the final HP output?  I'll start the bidding at 95rwkw.

Roger

You'll be waiting a long time for a dyno readout Roger. It's not going on the dyno - just straight into the Z & will be road tuned.

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The N42 head that I removed from the engine was (happily) in very good condition.
But before any machining work was started on it, I stripped it down to the bare casting, knocked the gallery plugs out from the ends of the head and sent it off to Woody's Hydrobasting for it to be water-jet blasted.
This  is a highly effective form of cleaning and removes ALL traces of oil, general crud & staining from ferrous and non ferrous metals, leaving a sealed finish like this:

IMG_20151218_172853_272_zpse860vxpg.jpg

 

The finish is so amazing that it looks like it's been painted.
It's also very resistive to staining, so it's easier to clean & keep clean.

 

It was then sent off to have the valve seats re-cut, valves refaced, valve guides honed, straightened (it had a tiny bend in it) and the top & bottom faces surfaced.

When it came back (in disassembled form) I asked Les if it'd be beneficial to clean the ports up - specifically the bowl area behind the valve and the short turn radius.
Cue an impromptu porting lesson from Les!

 

DSC_0538_zps1cid2ozp.jpg

 

2 HOURS LATER I had a cylinder head with reshaped bowls, sort turns AND chambers. My hands were also jelly from holding onto the Burr Grinder :(
It's hard to see from the photo, but a significant amount of material has been removed from the intake short turns.
I invested WAY more work into this than was really necessary - esp considering the relatively low CR & mild cam, but it makes for a really good cylinder head - and I learnt a LOT to...

DSC_0537_zpsmk26tudw.jpg

After this, I washed the head down & began reassembly.
The valve spring (hardened) base washers were re-installed, new valve stem seals, then the original valves with their lubed guides were pushed back into place &

the standard valve springs & retainers re-installed.

FWIW the 733a grind cam doesn't require upgraded valve springs or thicker lash pads.
Next the rocker post inserts were installed, then the camshaft towers were carefully installed & torqued down. I lubed the bearings up & slid the cam in - to my relief the cam spun freely!
Following this, the rocker posts were re-installed, std lash pads (taking note to check they weren't badly worn) then a set of refaced rockers, clips & springs.
Last but not least, new gallery plugs were knocked back into place, and a replated timing chain inspection cover & bolts.

DSC_0539_zps3nuvamyf.jpg

 

I then CC'd the No1 chamber and it measured at 44cc - bang on the money ;)

So it's moving along! 
Next up the block comes back from the engine machining shop...
TBC!

 

 

Edited by Lurch ™
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Hi Lurch

Nice head job..... the hydroblasting certainly does a great job.... sadly my nearest one is 300km away.... you mentioned fitting new gallery plugs..

are you reffering to the threaded ones that go into the water jacket? I have a couple of heads here ( E88) and they have thread tape on those plugs .. I assumed that is not from the factory can you tell me if I'm correct in thinking that?

 

Cheers

Pete

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Hi Lurch

Nice head job.....

 

Errr... Thanks Pete....
 

 

sadly my nearest one is 300km away.... you mentioned fitting new gallery plugs..

are you reffering to the threaded ones that go into the water jacket? I have a couple of heads here ( E88) and they have thread tape on those plugs .. I assumed that is not from the factory can you tell me if I'm correct in thinking that?

 

Cheers

Pete

Postage / freight isn't that expensive Pete - heck, send items down to me & I'll get it WJ Blasted for you.
No - not those ones. They stay put & are installed at the factory with that thread tape. Don't remove them.
I'm referring to the OIL gallery plugs at the END's of the heads - about 10mm in dia.

 

DSC_0539crop_zpsvadl0he7.jpg

And for those wanting to know, the cost to water-jet blast a head is around $130.00

Edited by Lurch ™
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Thanks again for the information.....I paid about $350 to have carbies ( they were dismantled ) and manifolds done....great job ...not sure haow that would compare with you blaster. I didin't notice the oil gallery plugs but they are obvious now....solid aluminium plug by the look of it. As for the thread tape ..again thanks...but I was surprised to straggly pieces of it after the head was cleaned. I thought they would have used a chemical sealant of some type.

I'll follow your rebuild thread with interest.

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The rebuild continues! 

The machine shop  did an excellent job; the block was hot tanked, then 'Simon the Borer' strainer plate bored the block oversize and then Diamond honed to get the bores bang on 87mm.
Then the block deck (with timing cover) were milled (square with the crank tunnel) to produce a perfectly smooth finish.

 

When it returned to LCR's shop I noticed some casting flashing in the crankcase, so out with the pneumatic air linisher & burr grinder and
I set about removing high spots from the crankcase that could lead to them breaking off in the future. It also helps with oil drain-back.
On a scale of 1 to 5 (5 being REALLY bad for casting flash) this block would be a '2', so it was pretty good.

DSC_0554_zpsiyeo5hwg.jpg

 

Next I tapped the oil pressure releif valve port to 3/8 BSP. (3/8 NPT is also fine - just make sure the correct gas plug is used. They are NOT interchangeable!)

Before I screwed the plug in & pumped some brake cleaner down the oil gallery from the front of the block, pushed a barrel cleaner up the gallery, then blew out any remaining swarf that had accumulated there after tapping the thread.

Once that was done the gas plug was screwed permanently into place.

 

DSC_0555_zps2jox3lys.jpg

 

With the block thoughtfully washed inside & out to remove any grit or swarf, I could paint the outside with engine paint and install the Welch/Freeze/Core plugs,

not forgetting the two small steel oil gallery plugs at the ends of the block. Then the dipstick & oil filter adapter.

DSC_0557_zpsgbz2h2cu.jpg

 

DSC_0558_zpsrvjhrmsh.jpg

 

With the block painted it was time to gap the rings.

This is a time consuming job to to, so much so that many people forgo this step if they can see a gap when the ring is installed into the bore.

I hope it is obvious by now that I wasn't about to do that!
Each piston rings was slipped into the top of the bore, pushed 40mm down and the gap inspected.

 

My aim for the minimum gap for top ring - which is double cast sided molly item -  is: 14 thou/inch
My aim for the minimum gap for second ring - which is a plain cast ring - is: 17 thou/inch
Oil control rings simply need a visible gap & the scraper ring has to touch ends but NOT deform when inserted into the top of the bore.

 

Most of the rings were above minimum tolerence, but a couple needed a lick on the rings grinder:

 

IMG_20151218_083808_244_zpsx0c47hqm.jpg

 

After which the gap was checked with a feeler gauge:

 

(Light refraction makes it look like the ends are misaligned, but it is not)

IMG_20151218_083405_781_zpshayixtez.jpg
 

Done!

 

IMG_20151218_083241_487_zpsapi9pbh0.jpg

 

6 top rings

6 second rings

6 oil scraper rings

12 oil control rings

It took a while!

TBC...

 

 

 

 

 

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Next I tapped the oil pressure releif valve port to 3/8 BSP. (3/8 NPT is also fine - just make sure the correct gas plug is used.

Question about this, usually there is a 1 way valve/ball bearing in this slot. Can you tell me why it's now plugged up and what impact this might have on the motor? Does it increase oil pressure or is it redundant now with new oil filters etc..?

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The valve is there in case the filter gets blocked, so the oil can bypass the filter.

By removing the valve, the filter see's full oil pressure & flow all of the time - the downside is IF you have a oil pressure spike or you don't change the oil and the filter clogs, you can blow the filter off...

 

IIRC You can buy the bypass valve assembly new from Nissan, if you want to reinstall it.

 

As this motor will be getting serviced every 5000kms with a fresh Castrol Edge and a new filter, this won't be a problem.

Edited by Lurch ™
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The valve is there in case the filter gets blocked, so the oil can bypass the filter.

By removing the valve, the filter see's full oil pressure & flow all of the time - the downside is IF you have a oil pressure spike or you don't change the oil and the filter clogs, you can blow the filter off...

 

IIRC You can buy the bypass valve assembly new from Nissan, if you want to reinstall it.

 

As this motor will be getting serviced every 5000kms with a fresh Castrol Edge Synthetic and a new filter, this won't be a problem.

That's one damn lucky motor!

Fantastic work Lurch, It will be a really strong build and it will treat every owner kindly thanks to your thorough work! Looking forward to the finished product.

 

Andrew

Edited by Andrew_L26
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That's one damn lucky motor!

Fantastic work Gav, It will be a really strong build and it will treat every owner kindly thanks to your thorough work! Looking forward to the finished product.

 

Andrew

 

Think you mean Lurch? This isn't my motor.

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Unless your the customer in question Gav. ;)

 

It's definitely not me, hand on heart. The hint is that this is an L28 rebuild. I'm likely going to be building an L24 bottom end.

 

I know who's build it is though, and only because of a clue I got before Locky deleted the post ;). That's all I'll say.

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Next I installed the main bearings into the block and torqued the main caps down, so the bearing size could be measured.

Les measured all these for me & the size fell between 2.2thou & 2.5thou, so we were good to continue.

Then we did the same with the rods (I didn't get a photo the std rods, so here's a H-beam being measured in the same way.)

IMG_20151219_103357_783_zpshftlwcnl.jpg

 

Next the crank was installed, making sure EVERYTHING was PERFECTLY clean. Any fluff or lint was picked off each crank journal, so it was spotless.
Then the bearing shells were oiled up, and I carefully lowered the crank into position, oiled the bearings in the main caps then installed them, torquing them up to 40ft/lbs. 

 

Pistons then needed to be installed onto the rods. The washed con-rods had their little ends heated to a 'straw' colour with the OxyAct torch, & the Gudgon pins pushed into place locking the pins in place on the rods with the pistons.

DSC_0521_zpsfnra0nsy.jpg

Once they cooled down I began installing the rings - unfortunately I forgot to get a photo with the rings installed, so just use your imagination...

DSC_0524_zpsh5fkhzwf.jpg

Then the bearing shells were installed into the rods, the shells oiled, the ring pack generously oiled & then slipped into the ring compressor (The ring pack is oiled so that it slips into the bore easily). 

 

DSC_0522_zpsh8es9zyy.jpg

 

I solid push & into the bore it goes:

 

DSC_0523_zps7wdjbvrx.jpg

 

Notice the notch on the piston is facing forward.

The rod is carefully guided onto it's crank pin, the rod cap installed & torqued up to 40ft/lbs as well.

This process is repeated for the remaining 5 assemblies, until I had this:

 

DSC_0525_zpsuxdfqafg.jpg

 

The short motor was then turned over, so the timing chain setup could be installed.

 

DSC_0527_zpsuyxvzmzy.jpg

 

First the front steel oil gallery plug had to be installed:

DSC_0528_zpsrtrc2yzr.jpg

 

Mmmmmm blurry....

 

DSC_0530_zpstehwvgns.jpg

 

Next the lower timing sproket was checked for wear, pronounced fit for use & installed onto the nose of the crank.

Next the Dizzy  drive gear was ready to go on, but  it was found to have excessive wear, so I went & hunted through my spares & found a matching spindle & drive gear.
This was washed up & installed onto the crank nose.

 

DSC_0533_zpse2p83qap.jpg

 

Then the Dizzy drive spindle was checked for end-float in the timing cover (with the oil pump installed).

The end float was excessive, so I went looking for a suitable hardend washer of the correct thickness:

 

DSC_0534_zpsxivzmenx.jpg

 

Bingo!

The end-float was now less than 2thou, so I was good to continue.

Next the head dowels, gasket & head were sat on (cam lobes 1 & 2 set to fully open or 'rock'), which allowed me to set up the timing chain.

New Japanese chain, guides & new hydraulic tensioner was installed with the original cam sprocket. 

 

DSC_0535_zpshbgt08kz.jpg

 

After all the timing gear was installed & done up tight, I installed the front timing cover & gaskets, and the water pump with the re-plated bolts.

I then torqued the head down.

 

DSC_0536_zpsvevedqtt.jpg

 

A little 3-Bond is wiped around the WP 'through bolts' to stop them potentially weeping coolant.

 

DSC_0537%202_zpsvzbikivb.jpg

 

Finally the oil-pickup & repainted sump was bolted back on.

Then the (primed) oil pump & dizzy drive spindle were installed, along with the new Scorcher Dizzy. Not forgetting the front oil seal, Harmonic balancer, lower Alternator mount & water outlet:

 

DSC_0542_zpsvq4yfl9n.jpg

 

DSC_0538%202_zps6fl7ruz6.jpg

 

DSC_0541_zpsbi3rxnoq.jpg

 

DSC_0539%202_zpso86cqf3l.jpg

 

DSC_0540_zpsajzutz7a.jpg

 

DSC_0545_zpsfjevlg5u.jpg

 

DSC_0544_zpskbuaopie.jpg

 

And that's it!

Well not quite - I still have some ancillary components to install on the engine, but that will happen when the customer brings their 240Z in to have the engines swapped.

 

While I haven't covered every little detail in building this engine, I hope you enjoyed this little tour of PROPERLY rebuilding an L6.
I shall update this thread when the engine is installed, around March.
Any questions, please feel free to ask :)

 

Again a HUGE thanks to Les at Les Collins Racing for allowing me to build this engine at his shop!

Cheers,

Locky.

Edited by Lurch ™
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