Rebuilding Our LS1 Engine Again | Project LS-Swapped 350Z

Tom
Update by Tom Suddard to the Nissan 350Z project car
Jul 2, 2021

Photography by Tom Suddard

Five years ago, this project started with an engine. In fact, we didn’t even know what car we’d be installing our LS1 in. We just knew that buying the disassembled V8 for just $400 was a decision we wouldn’t regret.

Over the months that followed, we signed up for Daytona State College’s Performance Engine Rebuilding and Machining course, spending our evenings rebuilding the LS1 to turn it into the heart of our 350Z that’s now destined for time trials.

That destiny brought with it the need for more power, so we ordered a new set of Air Flow Research heads and two new camshafts from COMP in hopes of making enough power to be competitive in NASA TT2 competition.

With a pile of shiny new parts in hand, our next step was dyno testing, so we called up our friends at Very Cool Parts. Not only do the folks there have a Mustang chassis dynamometer and LS tuning talent in-house, they also have the patience for us to monopolize them for a few days while testing various cylinder head and camshaft combinations.

It was the perfect plan: Drive to Alabama with the 350Z in tow, spend some quality time changing parts, and drive home with at least 50 more horsepower.

We were determined to have a successful dyno session, which is why we did our homework ahead of time. We checked the basics: fuel, air and spark. We didn’t want something simple like a bad coil pack or a clogged fuel filter to burn valuable time on the rollers. But remember what they say about the best laid plans?

[13 Easy Tips for a Successful Dyno Session]

We also spent some time setting up our AEM CD-7L digital dash, making sure to wire up an oil pressure sensor. That data will be prominently displayed (as well as recorded) whenever the car is running.

Thanks to our LOJ Conversions wiring harness, the car’s factory oil pressure gauge worked well, but it wasn’t very precise: The 350Z’s analog gauge only has five marks and two numbers, 60 and 120 psi, which is fine for a street car but left us wanting more detailed information before doing back-to-back dyno pulls.

Sadly, hooking up the oil pressure sender to our AEM dash probably saved our engine: by telling us we’d already ruined it.

Our LS1 now had noticeably lower oil pressure than before—our HP Tuners logs from startup revealed the bad news. That’s not a big deal if you’ve been driving 200,000 miles. We’d driven less than 200.

Clearly something was wrong, and the only question was how much damage we’d done so far. We got nauseous when we cut open the oil filter and found it full of metal.

Our next step? Call for help, of course.

We phoned Very Cool Parts owner Wayne Presley, explained what happened, and asked what to do before coming to visit. His answer: Pull a main bearing cap and see what stories it has to tell.

So we did, pulling the engine, then the oil pan, then a main bearing cap. The wear pattern showed that the bearing journal was not round. We found a bearing that wasn’t ruined but had definitely seen some bad things in its short life.

Our LS1 officially needed to be rebuilt again, but we weren’t going to tempt fate twice and do it ourselves. Instead, we dropped the engine back into the car (sans oil pan), loaded it into the trailer, and drove to Very Cool Parts anyway. An appointment is a promise, after all, and we don’t have a trusted machine shop here in town. So why not make this Wayne’s problem?

After arriving, we yanked the engine back out and gave it a proper teardown. The news was better than we feared: Sure, there was some metal in the oil pan, but the rod bearings looked perfect, and the main bearings were all still in place, if a bit worse for wear.

Our forged crankshaft, a big-ticket item from K1 Technologies, was unscathed. Bottom line: We’d caught it in time.

But we needed to fix our engine, which meant a trip to visit the experts at Pilcher Automotive & Machine Shop in Chancellor, Alabama.

We knew we were in the right place as soon as we walked in: The shop is always littered with aluminum small-block Chevy engines, many making horsepower numbers well into four-digit territory. Our problem would be a cakewalk for them, at least compared to the billet aluminum block they were welding up when we arrived—a rod had punched a hole through the side of it.

After a quick inspection and a few measurements, Pilcher’s prescribed a course of action: They’d line-hone our LS1, install a fresh set of bearings, and blueprint the tolerances to build an engine that should hold up to racing.

Didn’t we already do that when we built the engine? Well, no. Because everything measured in spec, or at least we thought it did, we’d skipped honing our block’s mains and assembled it without any additional machining.

Pilcher’s theory for why it had broken revolved around this oversight: Substituting ARP hardware increased the clamping force compared to the OEM main bolts, which meant our main bearings were no longer round when we were racing our 350Z, causing the premature wear and drop in oil pressure. Of course, they added a caveat: “That’s assuming nothing else is wrong; are you sure your oil pickup is healthy?”

We weren’t, but we’ll get to that later. For the moment we left our LS1 at the machine shop and hoped rebuild number two would last longer than our first attempt. 

Just 36 hours later, we were back at Pilcher’s to pick up our freshly honed and cleaned engine block. A full set of shiny new main bearings were already installed and the main caps torqued to spec.

We felt good about paying the experts for assembly, especially after we learned that they’d used different thicknesses of main bearings to get the perfect tolerance on each.

How much for the work? Let’s just say that we need to profusely thank Pilcher’s for going easy on our wallets while doing a month’s worth of work in just a day and a half. Next time we need an engine built, we’ll head back to Alabama.

Back at Very Cool Parts, we went to work turning our block back into an engine. But we did it knowing there was a killer on the loose, and we needed to find it before it struck again: We still didn’t have a great explanation for the source of that metal in the oil filter.

Sure, we had our theories: Maybe the metal was left over from a machining process. Maybe it came with some oil we bought. Maybe it came with the oil filter? Maybe we’d just been too sloppy when cutting the oil filter apart.

But these were just theories, and Occam’s razor pointed to a much simpler explanation: We’d screwed up, and our engine was grinding itself apart every time it ran. We just needed to find our mistake before the valve covers were back on.

So we tip-toed through the reassembly of our LS1, installing a piston and rod, spinning the engine two full revolutions, then moving onto the next to start the process over again.

We did find one problem: a chipped bolt head on one of the ARP connecting rod bolts. We chalked that up to hasty 1 a.m. removal with an impact gun and grabbed a replacement from Pilcher’s spares pile.

After crawling through the rotating assembly, we installed our new COMP Cam and a fresh Melling M295HV oil pump. Factory LS oil pumps tend to cavitate at higher engine speeds—we’ve heard 6200 rpm is the safe upper limit—but this high-volume Melling part should offer less cavitation and more consistent oil flow even at high engine speeds. We’re hoping it will tide us over until we have time to make the switch to a dry-sump system.

So far, so good: Our engine spun freely and everything was happily returning to its old home.

Then we put the oil pickup on, spun the engine through its first revolution and… TINK.

Damn. A closer look revealed a slight nick in the oil pump pickup, which matched up nicely with the ARP connecting rod bolt we’d replaced.

Turns out we hadn’t knocked the bolt head off with an impact gun: We’d ground it down on our oil pickup. We’d found the source of our metal. These K1 Technologies rods are beefier than the stock parts, and that extra material raised the bolt just enough to interfere with our oil pickup tube.

But just because we found one problem doesn’t mean we’d found them all. Whacking your oil pickup with a spinning connecting rod isn’t great for its geometry, and some modeling clay confirmed that our pickup was pressed firmly against the bottom of our oil pan. Not only was our engine using its pickup tube like a mandolin, it was trying to suck oil through a closed door, too.

While the problem was bad, the fix wasn’t: Wayne spent 15 minutes with a welder and a grinder, returning with a pickup tube that cleared the rotating assembly and kept the proper distance from the bottom of the pan. Hooray for oil filters, but let’s not try this stunt again.

Now that we’d found the culprit, we could have some fun. We bolted on our shiny new Air Flow Research heads, topping things off with a new valley cover from Massive Speed System. This part saved some weight and potential failure points, as it deleted the extraneous Gen III knock sensor mounts in the middle of our OEM valley cover.

All that was left was the valvetrain, and we threw more shiny parts at our LS1 here. We’d originally assembled the engine with Scorpion 1.8:1 ratio rocker arms, which gave our mild cam a bit more lift and duration at the valve.

But now that we were aiming to spin past 7000 rpm—and do it with a burly new COMP cam—we decided to drop back to the gentler OEM rocker arm ratio, 1.7:1.

We couldn’t use OEM rocker arms, however, as they have a tendency to explode when spun quickly. That’s why we installed COMP cams part No. 1981-16, a $650 Max-Life BSR shaft-mounted rocker system designed for cathedral port heads like ours.

This upgrade is an improvement over the factory rocker arms in two ways: First, it features bigger, stronger bearings that won’t come apart with high spring pressures over high engine speeds.

Second, mounting the rockers on one big shaft keeps them pointed in the right direction and helps prevent broken pedestals. Just like we leaned on Wayne for support in these trying times, our rocker arms would lean on each other for support when being thrashed on track.

One problem with these fancy rocker arms: They interfere with the stock valve covers. That added another $215 to our shopping cart, as we needed a set of tall LS valve covers from Holley (part No. 241-164) to finally seal our engine. Unfortunately, they were backordered, so we dropped our LS1 back into the car and headed home to wait for a delivery truck.

We’d spent three days at the dyno without hitting the rollers, instead leaving the shop littered with tools. At least we made new friends at Pilcher’s, right? (Although they probably smiled when we stopped blowing up their phone.) At least we’d avoided catastrophic failure.

Back home, our valve covers arrived and we finished reassembling our 350Z. As promised, the Holley covers fit just like the OEM parts, but with enough room for our huge rocker assemblies. Bonus points for having the coil mounts cast right in place, too, meaning we could save about a pound of weight by throwing out the OEM coil mounts.

And since there was already a Holley truck on its way, we splurged and upgraded to a $450 set of MSD coils, too. We’re skeptical of any claims of increased power with a naturally aspirated application like ours, but we’d already rolled the dice on enough dyno sessions with the nasty 20-year-old coils that came with our engine and figured starting with fresh parts was worth it. Plus, they look great, and we saved about $150 compared to buying eight new coils from the local parts store.

With the engine sealed up again, we were onto the details. We took this opportunity to add some DEI heat insulation to the 350Z’s starter power wire as well as tidy our oil accumulator plumbing a bit with some new Earl’s fittings and tools.

Headers can be rough on plug wires, so we also added a set of DEI spark plug boot and wire protectors, which should prevent our new MSD wires from becoming as crispy as the OEM wires we removed with the engine.

With the odds and ends finally finished, there was one step left: pre-lubing the engine before its first start. It’s important to circulate oil through any fresh rebuild before starting it, and you’ve probably heard the old-timers talking about pulling the distributor to spin the oil pump with a drill on their small-block Chevy.

Since our LS1 drives the oil pump from the crankshaft rather than from the distributor, there’s no way to spin the pump while the engine is in the car, and cranking the engine with the starter isn’t the kindest way to introduce its new parts to each other.

Instead, we used a Summit Racing Engine Preluber. This $170 aluminum tank looks like an air bottle and holds a few gallons of oil and compressed air for pressure. We screwed an Earl’s adapter fitting onto its hose, hooked it to an oil plug on the side of our LS, and pushed oil through the engine for a few minutes.

Then we flipped the switch, pushed the “Start” button and watched the dash: Our LS1 fired right up, making a steady 48.7 psi of oil pressure at idle. We’ll call this mission a success.

What’s next for our 350Z? Now that it has oil pressure, the path forward is clear: We really, really need to hit the dyno. We’ll do that in the next installment.

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Comments
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CrustyRedXpress
CrustyRedXpress HalfDork
6/24/21 1:47 p.m.

What a ride.

So the oil pickup was causing low oil pressure, right? But what was causing the metal shavings? The rod bolt and oil pickup interference?

Jerry From LA
Jerry From LA SuperDork
6/24/21 2:36 p.m.

This better not be the last motor you build.  You made one mistake and you caught it.  That's all. 

Were it me, I might've started with a stock-ish rebuild of something.  Maybe a slightly hotter cam and some bolt-ons for a little extra oomph without altering the basic architecture .  Maybe the reciprocating /rotary parts would remain stock with some premium bearings.  That way, you can practice the vagaries of the basic relationships (like piston-to-wall, ring gaps, bearing clearances, and pushrod length) before getting into the exotica.  It's hard to eat a steak by shoving a cow into your mouth.

Find some derelict and forlorn engine with some parts availability in the boneyard.  Make it into a useful tool again.  Run it for awhile so you can get some satisfaction and sell it on or give it to somebody who needs it.  I built maybe four engines before I started messing around.  You won't have to do that many.

Streetwiseguy
Streetwiseguy MegaDork
6/24/21 3:00 p.m.

Oil pump pickups are important.  I've always looked sideways at the aftermarket style you used, because I  picture hitting the wrong pothole just the right way, and pushing the pan up to block flow.   I prefer the stock appearing one that is designed like a babies nose- it can breathe even when stuffed right into something soft.

Stefan (Forum Supporter)
Stefan (Forum Supporter) MegaDork
6/24/21 3:05 p.m.

I'm getting flashbacks of the ill-fated Camry V6 project.

wheelsmithy (Joe-with-an-L)
wheelsmithy (Joe-with-an-L) GRM+ Memberand PowerDork
6/24/21 5:51 p.m.

Nice recovery. Hopefully the omelet is worth the broken eggs.

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
6/24/21 6:10 p.m.
Jerry From LA said:

This better not be the last motor you build.  You made one mistake and you caught it.  That's all. 

Were it me, I might've started with a stock-ish rebuild of something.  Maybe a slightly hotter cam and some bolt-ons for a little extra oomph without altering the basic architecture .  Maybe the reciprocating /rotary parts would remain stock with some premium bearings.  That way, you can practice the vagaries of the basic relationships (like piston-to-wall, ring gaps, bearing clearances, and pushrod length) before getting into the exotica.  It's hard to eat a steak by shoving a cow into your mouth.

Find some derelict and forlorn engine with some parts availability in the boneyard.  Make it into a useful tool again.  Run it for awhile so you can get some satisfaction and sell it on or give it to somebody who needs it.  I built maybe four engines before I started messing around.  You won't have to do that many.

Some parts availability...like a Chevy V8 from a couple of decades ago? ;) Thing is, GRM is a magazine with advertisers that love to get their parts in the magazine, so it's kinda hard to avoid the big parts cannon. Heck, it's easier than finding stock parts.

So if I read this right, the failure was due to a poorly built or designed aftermarket pickup, which was required due to the non-standard engine install. The rest is just playing. It'll be interesting to see how it holds up, I think every LS failure I've had was due to aftermarket parts. It's no coincidence that every part in my engine these days has a GM part number.

Let's see how long it takes before that billet oil filler cap gets replaced with a plastic one because someone's tired of branding themselves to add oil. See Raiders of the Lost Ark for reference.

noddaz
noddaz GRM+ Memberand UberDork
6/24/21 8:04 p.m.

And this is why I love this place.  You came and almost got your butt kicked and moved on and saved the day.  No our junkyard engine had low oil pressure so we bought a new one from GM. You dug in, got your hands dirty building the engine and car.  Things go sideways and you dig in again and hopefully we all learned something in the process.

Worst meme ever.

Anyway, keep doing what you are doing!

 

Scott

CyberEric
CyberEric Dork
6/24/21 8:07 p.m.

I really hope the new engine is better. God speed.

I’m suspicious of the LS swap thing. Have been for years. It seems like I hear a lot of people with a similar problem with oil starvation. Vorschlag ran into it long ago. I hear about it again and again. Even the GRM Z06 has a wet sump now to avoid the issue. 

I get it’s a compact motor with great power, but yeah, I feel nervous. Guess that’s why I’m slow!

dean1484
dean1484 GRM+ Memberand MegaDork
6/24/21 8:16 p.m.

Looks like you got that one just in time. The rod bolt thing was really interesting!!!  Did you figure put how the pickup depth happened?  Could  the rod hitting the tube bend it down? From what I know there is not a lot of clearance when set properly but  I have never done a complete rebuild of an LS motor and as such I found this really interesting. 

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
6/24/21 8:36 p.m.

Lesson to be had:  The corollary to line honing a block with the bolts torqued to spec, is that if you change the torque spec, you have to line hone the block again.

 

And people wonder why I am super critical about "unimportant" fasteners like cam cap bolts.

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
6/24/21 9:19 p.m.

In reply to dean1484 :

I suspect that the problem was the original dimensions of the pickup, that put it into contact with the bottom of the sump and the rod bolt. Good thing it made contact with the bolt, really.

Jerry From LA
Jerry From LA SuperDork
6/25/21 1:06 a.m.
Keith Tanner said:

Some parts availability...like a Chevy V8 from a couple of decades ago? ;) Thing is, GRM is a magazine with advertisers that love to get their parts in the magazine, so it's kinda hard to avoid the big parts cannon. Heck, it's easier than finding stock parts.

So if I read this right, the failure was due to a poorly built or designed aftermarket pickup, which was required due to the non-standard engine install. The rest is just playing. It'll be interesting to see how it holds up, I think every LS failure I've had was due to aftermarket parts. It's no coincidence that every part in my engine these days has a GM part number.

Let's see how long it takes before that billet oil filler cap gets replaced with a plastic one because someone's tired of branding themselves to add oil. See Raiders of the Lost Ark for reference.

What I meant was doing a couple of stock motors on the side until he gains a level of familiarity with the process beyond the book-learning aspect.  It doesn't have to be a V-8 or it could've been a bone-stock LS.  Whatever it takes to build the muscle memory.  If I recall, Chevy has been known to buy advertising too so a recent motor with gennie GM parts (plus a few bolt-ons or a mild cam from their catalog) might pique their interest.  Then the side project becomes a front-and-center project.  There's plenty to check on a stock build without worrying about the relationship between new rods from Manufacturer A, a crank from Manufacturer B, pistons from Manufacturer C, a wild cam and lifters from Manufacturer D, and all held together with bolts from Manufacturer E.

jharry3
jharry3 GRM+ Memberand Dork
6/25/21 7:58 a.m.

Note to self: Next time put the clay in a baggie so it doesn't gunk up the oil intake screen.

Tom Suddard
Tom Suddard GRM+ Memberand Director of Marketing & Digital Assets
6/25/21 9:12 a.m.

In reply to jharry3 :

Yeah, learned that trick on the second test-fit. laugh

And we did measure the pickup and pan when we originally assembled the engine, but either we measured wrong, we didn't account for something during assembly, or something changed. The rod bolt was definitely interfering from day one, though. Missed that and we were in such a hurry doing the swap that we didn't spin the engine after installing the pickup.

Overall, though, it was a great learning experience and I'm happy I caught it in time. All part of the process! 

Robbie (Forum Supporter)
Robbie (Forum Supporter) GRM+ Memberand MegaDork
6/25/21 9:44 a.m.

My first engine rebuild lasted about 17 miles before it threw a rod (mgb 1800). I'm mostly certain it was incorrect torque on the bolts. 

But I also think that until you try and rebuild your own, it is easy to not have an appreciation for how good a factory engine actually is. 

frenchyd
frenchyd UltimaDork
6/25/21 9:54 a.m.

In reply to Robbie (Forum Supporter) :

We should start a separate thread about early rebuilding experiences. But chances are your MG rod failure  had more to do with a rod bolt failure, than anything else.  
      First engine I actually "helped" rebuild was a 270 Offenhauser sprint car engine. The lessons  I learned  set the foundation  for all subsequent rebuilds/ modifications. 

Jerry From LA
Jerry From LA SuperDork
6/25/21 10:44 a.m.

My first was a 1608cc FIAT twincam I was getting paid for.  It took me like three months because I checked everything 362 times.  The only non-stock item was a set of oversize pistons and rings.  There was a FIAT parts distributor operating out of his basement about a mile from my place so I was lucky to have access to original parts.  The engine came out fine due to the great fear level in screwing it up and having to refund the money.  However, I also rebuilt the carb which need a couple of passes to get correct.

The most problematic was a Triumph Dolomite engine (essentially half a Stag motor) found in pre-'73 SAAB 99s.  The biggest issues were around casting porosity and it being a Triumph Dolomite motor.  That one I did for myself.  After months of struggle, I got it back together and drove it across the country.

f1carguy
f1carguy New Reader
6/30/21 7:24 p.m.

I need help! Where do I find the rod bolts on my Mazda 13B?

amg_rx7 (Forum Supporter)
amg_rx7 (Forum Supporter) SuperDork
7/1/21 1:01 a.m.

Should have rotary swapped it. :)

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
7/1/21 12:03 p.m.
f1carguy said:

I need help! Where do I find the rod bolts on my Mazda 13B?

They're hidden by the cam caps.

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