Cam install/Spring height/Rocker dilemma

[2eighTZ4me]

If he's going to sink valves and carve out the head, he's reducing squish as well. The gasket just does it evenly across the bore, rather than concentrating it in a valve pocket. Your "mixing" would occur at the induction phase on its' way to the cylinder, although, I would imagine more mixing could occur in the cylinder as well, but the theory is to have the fuel/air charge atomized and mixed before it even gets inside the combustion chamber.

 

I'm not a professional machinist, nor a pro engine builder, but would like to hear a little more explanation on "lean spots" inside the cylinder. I need to be educated on this point.

 

Have you pulled your front cover yet and spun the block to TDC yet? If you have a stroker, you should have the piston sticking up out of the cylinder about .6mm at TDC.

 

I may not have read it in the post, but have you mic'd your pistons to find out the bore size? That will help narrow down half of the equation.

[Tony D]

That's a funy statement "It's not an L28 Head" and using buffed Nissan and Identifiers as a rationale for that is spurious.

 

It's a late-model L28 Head from the JDM, and if the combustion chambers are small, likely they have been welded. Usually based off an N42 head---which was the standard in JDM well into the 90's. They simply didn't have P90's there, the L28ET was not available domestically, and the P79 was not an emissions requirement. Almost everything in the JDM came with an N42, and in several variations that were not seen in America.

 

The options for the head would be from an L26 (one year, and recalled for the most part, bery rare in the JDM and not EFI notched to boot!) or an L28 with an N42.

 

It's an L28 head. It's just the chambers have been reworked, and the chamber volume dropped through the 3mm milling operation mentioned.

 

I used to buy Dashracer 100 for between 95 and 100 yen a litre, and drove around happily heavily boosting on 8.5 CR. The N/A guys ran 11.5+ on a regular basis for street cars. During gas wars, the price could drop to as low as 25 yen a liter! When the yen exchange was 131 to a dollar, it was pricey, but for the first three years I was there and the exchange rate was over 200/250 to a dollar, it was pure heaven! Why pay a $ a gallon for MoGas on base when Dashracer 100 awaits for the same price just outside the main gate. Dorm rats need not apply.

 

The mindset in Japan is different than elsewhere, and if you approach the work they did there from a non-Japanese point of view you will convince yourself of a lot of assumptions that simply are wrong.

 

I should go take some photos of some 'street heads' I have out in the shed... there are people who would swear they were 'full race' but I can personally attest they were in cars that were street driven daily, and simply maintained.

 

Then again, 50 mm Mikuinis were not a 'Street Carb' in the USA, either...

[Tony D]

Yeah, I'm pretty sure I have this exact same chamber configuration on an N42 out back in the shed. I don't know if I will have the time to access the thing to take a photo till Friday, but I'll make a note to try and do it. I'm going to be back home after dark today and tomorrow, and finding things in that shed is treacherous in the dark....

[Daeron]

I am going to ask something, a detail I am not 100% clear on....

 

Were all cylinder heads originally the same height, from firing deck to valve cover mating surface?

 

I'm not even close to sure on how to verify this guess, but after poring over the photos I am going to revise my guess to say EXTREMELY shaved N42

 

I KNEW it... what I would do if I were in your shoes, is get a stock thickness headgasket, and get pistons that be thick enough to allow you to machine a relief in the top that mirrors that combustion chamber, and still relieve enough compression to get you down to manageable range (whatever THAT should be, by your judgment/needs/fueling ability/etc).

 

The "mixing" you are speaking of I am fairly sure is "swirl" within the combustion chamber, and if I am not mistaken that is one of the parameters of the flame front expansion during the combustion event. You want nice, even expansion of the edge of the flame when the "kernel" pops, so to speak. This is also effected by your piston/cylinder head clearance (you need it to be VERY close to contacting those quench pads, I don't know the number off the top of my head) so spacing your head further away from the piston is problematic.

 

Let me interrupt this explanation to clarify that these comments pertain to CLOSED CHAMBER CYLINDER HEADS ONLY, such as the P90/79, the E31, and this shaved "N42" or whatever it is. Closed chamber means, it has those flush flat spots there, around the combustion chamber which is NOT a round opening the size of the cylinder bore, as you see in later E88s, and most american stock N-series heads (the MN47 being the major american-market exception to this)

 

Now, you want to leave a flat piston coming REALLY CLOSE to your flat quench pads, so you don't want to do TWO things:

 

1. Don't want a 3 inch tall head gasket to decrease compression

 

and

 

2. Don't want to have a piston DISH that misses quenching against this pad on the cylinder head either. You want flat top pistons, AT LEAST in the region where the quench pads are in the cylinder head. (I know, the turbo engines came with pistons that had a round dish in them, stock, despite the chamber shape.. "Why did Nissan do it wrong??" you want to ask. I don't know, probably money.)

 

So, draw an outline of your combustion chamber on the top of your flat-top piston, and start carving a relief that mimics the "relief" in the firing deck of the head that IS the combustion chamber. It can be somewhat smaller in overall "circumference" and a bit shallower; make it the volume that you need to to reduce the compression of the engine to your desired level. You are shooting for a face that is symmetrical with the face of the cylinder head.

 

This achieves your goal without losing the "high-quench" benefit that is typically assumed to be the performance key to building and tuning a high-comp engine with a closed chamber Z head. MUCH has been said, correct and incorrect, as part of an explanation or as part of an argument, about this subject; and *I* am by NO means a sagacious engine builder of much expertise.. but I HAVE grown up around these cars, and around men who knew these cars, and have been extremely critical and curious of all that I have seen or read, in person, in a book, or via the internet.

 

If anything I said was vaguely mis-stated, please correct me, but I am *pretty* sure I've hit this one.. am I right guys??

 

 

 

Edit:

Sorry to crow like a cock there at the beginning, but I was sorta proud that I was right, so don't read it as arrogance, read it as happiness.

[ozconnection]

Saw this cam and I thought I would post it. Reminded me of Babalouie's cam. I don't know what the letter 'F' means. I haven't seen that before.

[Babalouie]

That's a funy statement "It's not an L28 Head" and using buffed Nissan and Identifiers as a rationale for that is spurious.

AFAIK, it's not-uncommon in Japan to sand off the engine and head numbers, to hide the fact that you have up-engined your car. The road-tax over there is capacity-based you see, so admitting to 2800cc would have made the registration more expensive. The block clearly has N42 and L28 markings on it, so I guess it might just have been the shop practice of the place that did the cylinder head to machine off the head casting id.

 

The guy who's doing my head probably doesn't realise that there's a reason why ppl in Japan de-tag their engines and heads, so he's assumed that it's some sort of mystery-head.

[Babalouie]

Saw this cam and I thought I would post it. Reminded me of Babalouie's cam. I don't know what the letter 'F' means. I haven't seen that before.

My cam was machined much more than that I saw an article in a japanese mag of a 510 engine and the cam in that had the same amount machined off it. I've been meaning to ask someone japanese to read it to see if we can id the source of these cams.

[Tony D]

The block number really is all the Shaken-Sho goes by, they usually restamp it to get around the over 2-litre tax class fees.

The head numbers going away is more likely a 'clean work' kind of deal, cosmetic.

 

Really, in the JDM there wasn't a whole plethora of heads or blocks to be had. You got N42 for the 2.8's and that was about it. There were casting configurations within the N42 that we never saw in the states. I have a 1977 N42/N42 block head setup and it's flat topped pistons and 8.5CR...figure that one out. And I had all the maintenance records on that engine, and personally pulled it from the donor car (a corporate owned Cedric with 42,000 Km on it!)

 

It was a foregone conclusion that other than the E88 L26, and E31 L24 heads the N42 was what you got, and you simply welded and reworked it to get what you wanted.

 

It got busy this weekend, so no photos. It's raining today, but I'll try to make it out back with the flashlight and snap a photo of my head for comparison. I'm sure this head still has the casting number on it as well, and since it's been planed, you can see the reqork that was done to change it from the original N42 configuration.

 

After it's been in an engine and operating, without careful cleaning looking at a dirty combustion chamber would make one think it's a 'stock' setup, but in fact it's been welded and reworked extensively.

[Babalouie]

We have interesting new pictures!

Here's the latest reports from Tony the builder:

Got stuck in & found a few issues, nothing tragic tho.

The intake seats I had just intended to touch up & widen a bit - but several were not concentric with the valve guides, so I made the decision to re-cut them as well & while it was on the seat machine I re-cut the valve reliefs for better low lift flow & to unshroud the intake valves a bit more.

The seats have been set up to flow well at high lift, sacrificing some low lift flow to do so - so the bowl sizes are really a little large, I'll have to reshape the bottom cut of the seat by hand to boost low lift flow as much as I can & rework the short turns a little with the same in mind.

Pretty much the same story on the exhausts, except the bowl sizes are better. I sunk the exhaust seats .025" & re-cut the relief as well.

With the seats done & reliefs re-cut it's become obvious that the chambers are gonna need a bit more re-shaping than I anticipated.

The upside is that I'm gonna gain a fair bit more chamber volume than I thought & if the motor turns out to be stock stroke then a dish in the pistons may not be needed.

The only other issue that turned up was that the spot I thought had been welded turned ot to actually be 2-pac metal putty - discovered after bead blasting.

It seems to have been holding well tho, so not a major issue - I've blasted the old putty out & I'll re-fill the hole with devcon, let it cure good & proper & then pressure test to 40psi to be sure it'll be ok.

Welding is not really an option, the metal there is a bit too thin to weld reliably.

I've done 1 chamber to see how it's gonna come out - nice would be the answer.

Okey doke, all carbide cutter work is done, all port runners are final finished, 1 cylinders chamber, short turns & bowls done.

The area around the intake guide was not great - whoever ported the head did not remove the guides to do it, so there was a section that was a bit crappy. I bumped the guides down out the way & reshaped the guide boss a bit while I was in there with a grinder.

Porting finished, intake guides trimmed down a bit, head lightly milled on the top & bottom faces to true it.

Chamber volume has gone up to 35.5cc from 32.5cc.

With stock stroke & zero deck height that'll give approx 11.1-11.2:1, which is borderline with the 240/250 cam but would be ok with a good tune.

If the pistons are sitting a bit below the deck then setting deck height at .005" will give about 10.9-11:1, .010"deck height will give about 10.8:1.

So if it's stock stroke it won't need a dish in the pistons!

If its a stroker then comp with zero deck will be about 11.7:1 & will require a further 3cc dish in the slugs - which is quite small & very doable.

First the head is disassembled:

...where it is discovered that the valve seats are only 1/2mm (ie the valve seat only "seals" to the valve thru a thin contact patch 1/2mm wide). Tony said that was way too thin for longevity on the road, and is more evidence that this was a purpose built race head.

The head is bead blasted to clean it up.

Inpet ports are reshaped, you can see the valve guide boss has been trimmed down in size and made into a more streamlined shape. Also the surface finish of the inlet ports was deemed too smooth by Tony, and hence he roughed up the surface a bit to prevent fuel pooling on the port walls. One of the inlet ports had broken thru to water jacket by the head porter in Japan, and the hole was filled with 2 pack metal putty. It was holding ok, but Tony blasted it out, drilled out the hole and filled it properly with Devcon. He also said that the short turns (whatever they are!) were lumpy and ridged, so they're now smoothed and reshaped for better low-rpm flow.

Exhaust ports refinished too.

Almost the finished product....

...combustion chambers were opened up a little bit to unshroud and expose the valves, the valve were also not concentric in the seats, so he's recut them to be central, and also remachined them to widen the valve seat from the thin 1/2mm to more like 1mm.

The finished ports.

The head will be assembled, and then sent off for flow testing to see how much hp it will support...should be interesting. He said that if he were to start again, he wouldn't have the ports quite so big and the bowls would be smaller too, for better low-rpm flow, but just the same he's pretty happy with how it turned out.

[Drax240z]

Looks great... so did you pull the front cover and check the stroke yet, or did I miss that? You really need to know, and it's not a big deal from where you are at...

[Babalouie]

Looks great... so did you pull the front cover and check the stroke yet, or did I miss that? You really need to know, and it's not a big deal from where you are at...

No...still too lazy to have done that

[Daeron]

I cannot recall the specific clearance, but you need to get a flat top pistons (even one with a relief cut in it, if needed) VERY CLOSE to the firing deck to obtain proper quenching from that combustion chamber. 1fastZ is the one who I know knows that figure off the top of his head, any time I want to get it exact I embark on a search that involves his name and P90. something like .021" or .21mm, i think? Not sure if that is (+/_) deck height desired, or piston to head clearance, so I know I am not much help there, but I wanted to point it out nonetheless.

 

Secondly, I am curious about the angle left along the circumference in the combustion chamber.. At the deepest point its almost like a wall meeting a floor, rather than say, an emptied out swimming pool used for skateboarding (reaching for an illustration here) There is no radius, instead a sharpish turn.. Any experienced head porters want to comment on that? It seems unusual, but maybe I am mistaken.

 

 

BTW the "short turns" are the short side radiuses (radii) in the ports. The "roof" is the long side radius, and the floor is the short side radius. The reasoning is, the circle that the arc of each wall would form has a certain radius, and the upper wall would form a larger circle.

 

If you do cut reliefs out of flat top pistons to achieve desired compression, just take a peanut shaped bit off-center reflecting the combustion chamber.

[Babalouie]

Here's more updates from testing the completed head today:

 

Flow figures:

 

Intake

Lift Flow

.1 -- 58.8

.2 -- 113.8

.3 -- 153

.4 -- 187

.5 -- 215.8

.55 -- 223.6

.6 -- 226.9

 

Exhaust

.1 -- 43.2

.2 -- 80

.3 -- 102.1

.4 -- 128.8

.5 -- 144.1

.55 -- 151.5

.6 -- 156.6

 

in/ex ratio (%)

 

.1 -- 73

.2 -- 70

.3 -- 67

.4 -- 69

.5 -- 67

.55 -- 68

 

Average

in/ex ratio - 69%

 

Intake potential - 215.8cfm @ .5" lift = 331hp potential on a 6 cylinder.

 

Flow begins to taper off after .5-.55" lift - meaning that the head is pretty much ideally suited to a cam with around .5" lift' date=' if the flow was to continue to rise quickly above that lift then it's a good bet the ports/bowls are too big & the seat angle wrong.

 

So, basically, it's even better than I thought it'd turn out, although I would have liked to see a little more exhaust flow - but that ain't gonna happen without larger exhaust valves, the bowls & ports are pretty much maxxed out. It would seem the cam guys know that datto's aren't great on the exhausts, that'd explain the big forward split on the cam 240 deg on the intake & 250 on the exhaust - that'll make up for the not ideal exhaust flow nicely. I was initially thinking the cam may have a bit too much ex duration, but as it turns out it'll be spot on.

 

Babs - if you can measure the intake runner length (from end of carb stacks to manifold face) I'll run it through engine analyser pro & get an idea of the power curve.

 

Off the top of my head methinks it'll do 260-280hp, should make at least 200rwhp.[/quote']

 

Based on 38mm chokes in the webers' date=' 12" total intake runner length, 1.5" primary headers:

 

I musta got something wrong, EAP is predicting 401hp @ 6500rpm & 389ft/lbs at 4500rpm.

 

I'll put some smaller chokes in the carb & restrict the exhaust a bit to try to get a realistic figure out of it.

 

Ok, with 35mm chokes in the carbs & a street type exhaust it's still showing 370hp @ 7000rpm & 372ft/lbs at 4000rpm.

 

On pump fuel, with full exhaust system.[/quote']

 

Checked it again & again - can't find anything wrong with the sim' date=' if anything the values I've plugged in are conservative.

 

Even the knock values EAP is spitting out indicate that it'll be 100% fine on pump 98.

 

Gonna be a strong motor.[/quote']

 

Ooh that's promising

 

Okies....inlet is 28.5cm from air horn to manifold face.

 

Carbs are 40DCOE with 32mm chokes (I woulda thought this would be the biggest restriction).

 

Zorst is a dual system' date=' 43mm pipes. Headers are 6 into 2 (then it just goes dual, it never merges to 1) with 42mm primaries, 52mm secondaries.

 

BTW I think (got to take more time to measure it properly later) that deck height is negative 0.08mm.[/quote']

 

Ok' date=' with 32mm chokes etc she's still showing 345hp @ 6500rpm.

 

I had a chat with Peter Schaeffer coz I know he had a lot to do with dato's back in the day - I ran the combo past him & he said it'll make 300+hp on a bad day.

 

Stick a set of 45DCOE webers on it & it'll go 330-340hp without trying hard.

 

Any way you look at it the ♥♥♥♥♥♥♥ thing is gonna hammer.[/quote']

 

PS - the best Scaeffer has ever seen out of a dato head is 210cfm......

 

I may be able to source a set of 45dcoe's at a good price if you want them.

 

If you stick a set of 45's with 40mm chokes on it' date=' assume it's a 3.1L stroker & crank compression to 11.5 (which it would be if it was 3.1L):

 

Knock index is still fine, pump 98 no probs.

 

400hp @ 7000rpm - it'd do 360-370 in real life & should crank out 270-280hp atw.

 

Even with the big carbs & 7000rpm on board intake velocity tops out at mach .44 - which is real nice, damn near perfect actually.

 

I can't get those 45's - the guy sold them a coupla weeks ago.

 

But this motor will be begging for more carb - 45's would round out the engine real nice.[/quote']

 

Ok, everything washed up & laid out for some final checks.

 

I worked out how low I could grind the valve tips before lash cap clearance became an issue - I've left .020" clearance so the valves can be tipped again in the future if need be & ground them all to equal height within .002" so the rocker geometry is consistant between cylinders.

 

The valve tips still sit about 1.75mm higher than stock - so I was a little concerned about rocker geometry & decided to to a quick dummy up & check it.

Wipe pattern is nice & central & there is still plenty of adjustment left in the rocker posts = win.

 

Pics:

 

 

 

Refaced rocker arms refaced on both the cam contact pad & lash cap contact pad):

 

 

Th only potential hiccup left is valve spring installed height & seat pressure - as the valves have been sunk a total of almost 2.5mm into the chamber face the collet groove heights are around 2.5mm higher than stock, so spring installed height is gonna be up the ♥♥♥♥.

I'll have to put 3 sets of spring bases in to get it close to right & will check seat pressure from there - worst case I may have to make up a set of spring spacers.

Once I've got some retainers (no one wil admit to having any - everyone did the same as me & threw all the old datto stuff out a coupla years ago, bugger) I can also sus out what the old springs will give in the way of seat pressure & decide which way to go.

 

I just had a thought - I may be able to machine down the old retainers to allow the use of a stock lash cap & re-use the old springs - will go check.

 

Winnar!

 

With an old retainer machined flat on top (which still gives plenty of meat to retain a stock lash cap) it damn near fits, a little clearancing of the rocker arms & it does fit.

Rocker geometry is unchanged, old springs test up fine & will work with the higher installed height that is due to the valve seats being sunk so far.

There is still enough adjustment (not heaps, but enough).

 

Wins all round - Babs doesn't have to buy new springs & pay for me to machine up some spring spacers, I don't have the headfuck of making spring spacers & chasing down some stock retainers.

 

All good, just need a set of stock lash caps & some seals & I can put it together.

[Babalouie]

Latest Update:

 

BTW TK....would it be a big drama to punch in the values of the big jap cam into your Engine Analyser just for shitz and giggles?

 

You got the specs?

 

All I got is what I measured:

278 duration @ 50 thou

600 thou max valve lift

 

It dropped a bunch of torque through the midrange & only crossed over the power curve above 6000rpm - with the 40mm carbs.

 

The new cam with 45's shits on the old cam with 40's from a great height' date=' right through the rev range.

 

The old cam with 45's compared to the new cam with 45's - new cam shits on the old one up to 6500rpm, but old cam with 45's peaks at 440hp at 7800rpm.

 

BTW - comparing 40's to 45's with the engine as it will be shows the 40's are holding it back a fair bit from 4000rpm on - the 45's pick up a full 50hp at 6500rpm.

It doesn't drop any torque with the 45's either - the 40's won't make any more torque at all, even down at 2000rpm.

 

Hint - get 45's.

 

300hp may sound like a lot for now, but believe me, you'll get used to it pretty quick & want more - when that happens (notice I say when, not if....) 45's will fill the void in your soul.[/quote']

 

Interesting....I reckon I'll keep an eye out for 45DCOEs if any come up for sale, but I woulda thought that from a part-throttle response point of view the 40s would be better?

 

Nup.

 

People think that 45's are pretty big - & from a combined flow perspective they are' date=' but on an individual runner setup they're actually quite small.

With, say, a 750 holley on a v8 - each cylinder can draw through all 4 throats of the carb, but on an individual runner (IR) setup each cylinder can only draw through 1 throat of 1 carb - meaning that although the total flow capacity of 3x 45dcoe's is kinda huge each cylinder only see's 1/6 of that flow capability.

I don't think even a set of 48's or 52's would over carb it.....

 

The strong point of IR setups is very good intake pulse tuning - with no other cylinders drawing from the carb throat the pressure wave does not get diluted/mixed up & will reflect strongly from the end of the intake runner - hence intake runner length is a critical dimesion for IR setups & can be tweaked to move the torque curve around quite a lot.

 

ie.

 

shorter runners = more top end power

longer runners = more midrange torque

 

I just ran a coupla sims - it would seem that you would benefit from going back to 10" runner length, it'd smooth out the power curve, pick up some top end & would drop SFA torque.

The effect with 45's would be even greater, to the point that another 70hp on top of what it would produce as is with the 40's would probably be a reasonable expectation with 45's & 10" runners.[/quote']

 

So the simulation is telling us that the existing 40DCOE Webers are too small for the engine and we're choking peak power to the tune of maybe 50hp, and it seems that the bigger carbs won't even cause a loss of torque either, so it's all god. But just the same, it'll work well enough with 300hp and I've got bigger fish to fry with the rest of the car. So the 45DCOE Webers will be an upgrade we save for another day.

 

The huge Japanese cam got 440hp at nearly 8000rpm on the simulation, but was inferior to the new cam below 6k, which is no great surprise. No VTEC for me!

 

But now the head is assembled and complete!

 

Here it is with valves in place you can see the "shiny" bits of the combustion chamber are where it's been reshaped

 

The modified retainers. From this:

 

To this. The raised "collar" has been machined flat. Also the retainer edges have been machined down and given a bevelled edge to free up some space:

 

Rockers have been clearance lightly at the spot which used to touch the retainer too

 

Assembled with cam in place, and valve clearances set to 10 and 12 thou as per the cam card.

 

...and it's all done!

 

Soon we'll get the head back, and sometime in the very near future, the block will be pulled and we'll take that apart for a looksee.

[2eighTZ4me]

Drooooooooollllllll.......!!!!!!! That's one pretty piece there Babalouie!

[grumpyvette]

thats really impressive work

[Babalouie]

After a little hiatus...the engine is beig worked on again

 

It's at my friend Nathan's workshop. I figured since the head was full of custom stuff, the bottom end might be too, and so I better let a pro take a look at it.

 

The headline? It's a stock crank, so it's not a 3.1L stroker but only 2950cc.

 

But there's some interesting stuff. As expected, it's very fresh, and hasn't done more than maybe a thousand kms. It's also not very standard, but in line with the rest of the car, it's a weird mix of hi-end work and some very shocking shortcuts and laziness.

 

The pistons are a brand called ART, and are racing items, which very thin compression rings. Nathan says that as a result it'll have a somewhat shorter lifespan than normal, and also that we have less margin for error when tuning, as those thin rings will be more easily damaged than usual. It means that I might only have 100,000kms between rebuilds, but for a Sunday car this isn't a big problem.

 

Brass button clutch...

 

Balanced flywheel...

 

And a balanced crank. There's been quite a bit of material taken off it, so it's been lightened quite a bit, and is probably a new item since there's no wear on it. I think it's an N42 crank.

 

Here's a short cut though....after balancing, they didn't clean up the edges of the lightening holes....there are little curly bits of metal hanging off the edges, waiting to fall into the oil supply...

 

...which is undoubtedly what happened here. The bearings are all pretty new looking but two of them show that some metal has passed thru and scored the surfaces. Interestingly the Japanese builder built the bottom end with two sets of bearings. Both the upper and lower bearing have that groove in the middle, so they've used two top bearing shells on each journal (the other side is meant to be plain). By using two top/grooved halves, you reduce surface area and friction and hence make more power at the cost of a somewhat reduced lifespan. But it's not quite a "grenade" engine though and the clearances checked out perfectly with no wear on the crank journals. But when Nathan puts it back together, the engine will be rebuilt with conventional bearings for longer life.

 

Another short cut is balancing. Even though the crank and flywheel are balanced, there was a 10gram difference between the heaviest and lightest piston/rod! The whole set will be balanced before reassembly, but it's weird that you'd go to the trouble of preparing the crank and flywheel, and then undo all that good work with a very unbalanced set of pistons.

More dodginess awaits on the block...

 

As you can see here, the hole for the oil pickup is in the middle of the block. This is correct for a Z-car, which has the bowl of the sump at the back....

 

...but for a Skyline the sump bowl is in the front, so they modified the oil pickup tube to extend to the front bowl! Not exactly top notch workmanship...

 

The extended oil pickup tube also meant that they had to cut away the baffle in the sump to allow the pickup tube to pass thru. See that missing section from that plate in the middle of the sump? That plate is to stop oil from sloshing to the back of the sump under acceleration, where it will be frothed up by the crank, where it will not only cost power but also compromise the lubrication if the oil supply is full of bubbles.

 

Nathan will redrill the block to resite a new oil pickup tube at the front, where it can go straight down into the sump bowl. The old hole will be blocked up, and the sump baffle repaired. The bores are in great shape so they'll just be treated to a light hone.

 

The next step is for the block to be drilled, the welch plugs removed, and then it'll be tank cleaned and repainted before reassembly.

[blueking]

Mean machine. Would be be perfect in any weekend warrior. =D