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1995 L67 junkyard engine exploration


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2seater

     A short preface: This topic has been a long time coming and may be somewhat slow moving. I always wanted a supercharged engine for comparison to the turbocharged iterations I have experimented with for many years. None of this is hardcore performance, just what can be done with a little work and optimization. Originally I planned to add a supercharger to an LN3, our stock N/A engine from 88-90, or the 91 L27. With that in mind, and the spare block and heads I got from Daves89, I had it bored, and decked to end up with a 9:1 compression ratio and purchased pistons of an unusual design for an Australian Holden V6. I also purchased a S/C damper and had the rotating assembly balanced with the S/C damper. Moving forward, a couple of years ago, our largest local junkyard got in legal trouble and it looked like they were going to have to liquidate and shut down. With that in mind, the time to act took on more urgency, and thanks to Dave's help, I secured a complete take out '95 supercharged engine from a Riviera. Since it was listed as non running on their inventory, I bought it for the core engine price of $175, complete with alternator, power steering, a/c compressor and even the torque converter on the flexplate. It turned out they did not go out of business but it does seems prices have increased a bit and they are less inclined to let things slide.

 

     I finally started looking the engine over and noted it turns over freely and appears to have compression. All of the accessories also spin freely although the a/c compressor has since seized, probably from being open to atmosphere? My original intent was to just to salvage the supercharger but of course my curious self wonders if the entire package may be salvaged, either supercharged or more highly boosted turbocharged? The other engine is still in pieces but before I commit any more work on it, I intend to at least partially tear down my junkyard core. 

 

     I just spent a couple hours today stripping off the leftover wiring, belts, hoses and other misc. stuff, much of which had been cut or disabled by the removal crew at the junkyard. I noticed immediately the front motor mount is completely different, being bolted on the front corner of the engine rather than being part of the A/C compressor mount on ours. There is a massive aluminum casting bracket that covers the entire front (belt end) of the engine to the rear of the crank centerline, It carries the alternator and power steering pump as well as a single and double idler and a belt tensioner.  Unfortunately this bracket is cracked and the tensioner is broken. It is right at the bottom so it likely was more prone to damage. Attached is a photo.

 

    It appears the charcoal canister venting is done differently through a vacuum/electric valve on the intake manifold. The EGR is a totally different type and is located on the front of the intake manifold and attached to the front exhaust manifold. I suspect I could adapt our EGR to this location but it is in a butt ugly location. I would prefer to keep a functioning system rather than deleting it, but that is to be determined. When I removed the EGR I noted the intake manifold end of the feed pipe was slathered with a blue silicone (photo) as was one of the water pipes for the heater? Clearly not a stock repair. One of the fuel injectors was missing the clip that secures it to the fuel rail but otherwise everything looked pretty good and came apart smoothly. The fuel injector part number indicates they are 28# vs the 19# for the n/a engine. I need to investigate the proper removal procedure for the crank damper. It appears to have a plastic shield on the backside and if there are tapped holes, they are hidden inside three open slots on the front.

 

I don't know why the photo of the large bracket is turned sideways? I t should be rotated clockwise 90* to place the crack and broken tensioner at the bottom.2101562857_IMG_16891.thumb.JPG.a7e7062ce5c688f51429bd033bba06d7.JPG530735085_IMG_16871.thumb.JPG.a027e83e548ab080aeac8a90097d42d8.JPG

 

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Ronnie

 

 

1 hour ago, 2seater said:

Since it was listed as non running on their inventory, I bought it for the core engine price of $175,

You can't beat that price. Any ideas on why it wasn't running?  Did you get a starter, and if so would it be possible to spin it over on the engine stand to check compression before you tear it down so you will have some idea of it's mechanical condition?

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DAVES89

This is going to be a great thread to follow...

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2seater
11 hours ago, Ronnie said:

 

 

You can't beat that price. Any ideas on why it wasn't running?  Did you get a starter, and if so would it be possible to spin it over on the engine stand to check compression before you tear it down so you will have some idea of it's mechanical condition?

I do not have a starter for it and I have no idea why it didn't run. It actually was an accident victim, and I simply chose the engine out of several cars that were lined up, which I pointed out to the worker with the giant payloader who scooped it up and carried it away to be relieved of it's heart. It was a somewhat uncertain time for the yard and the counterman originally quoted me a little higher price, like $225. He lowered the price when I came to pick it up and called it a core engine, but I am not sure why? There is no doubt their familiarity with Dave has a positive effect on their attitude?

 

I intend to pull the heads and maybe a few bearings to look inside, even if it was a runner. I already know the crankshaft is different for two reasons, it has a one piece rear seal and the flexplate bolts on with eight bolts rather than six. I also know the rocker arms in the head have roller trunnions rather than the sled type pivot, but the arm itself is just stamped steel, similar to ours. The internal condition will determine what becomes of the longblock. 

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    I found out what it takes to pull the crank damper and I have M6x1.0 bolts, 4" long coming tomorrow which should work with my existing pullers. Until then I started stripping the top of the engine.

 

I pulled the supercharger first of course. If I hold the rotor inside the s/c and turn the drive pulley back and forth it I cannot detect any appreciable play in the drive system at the front. I do see the coating on the actual rotors is flaking off, which decreases efficiency by increasing clearance slightly. The intake manifold below the s/c is full of oily residue and what almost appears to be oil dry?? Not a lot, but it is filthy. I noticed the design of the lower manifold seems to be about as poor as I could imagine. Perhaps some day I can get a decent photo of the inside. I set a stock LN3 manifold on top of the lower for the s/c and it is easy to see the LN3 manifold is a form of what would be a short ram manifold with the runners angled straight down to the ports and valves in the head. The s/c lower actually angles slightly upwards to the entrance to the head. Compounding this is there is an empty recessed area between each pair of ports in the manifold, essentially an empty pocket with straight walls that protrude into the air stream. Hard to describe but I will see if I can figure out how to illustrate. Of course the supercharger sits where the intake plenum is for hood clearance so I understand some of the design but all the internal junk in the way makes little sense.

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When I received the engine initially I noticed the exhaust manifolds were a similar design to ours with some notable changes. They are tubular  and very similar up front except the front manifold also includes the crossover pipe to the rear as a single piece. In this case it also has the fitting for the EGR on the front manifold. The rear manifold is a different design while still being tubular sheet metal. It is definitely more efficient than ours. The construction is such that it appears as an upper and lower half with a seam along the entire length on both sides. The opening to the exhaust is completely clear and actually has a bit of a funnel shape for smoother flow and the stub pipes from the exhaust ports do not extend into the main log to introduce turbulence. The down side is there is no EGR tap but that could be added easily. The rear manifold is an exact replacement for ours in all other respects and I actually put it together with our front manifold and crossover pipe. Interestingly, the outlet stub is exactly the same as ours even though the rest of the exhaust system is supposedly larger diameter? It sure starts off as 2.25" even on the latest Series 1 supercharged.

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Moving on to the valley under the intake manifold, I was relieved to see it is generally clean with little residue and other associated debris from sitting in a salvage yard. I noted that the lifters are aligned using a plastic glove type arrangement. The steel dogbones and spring loaded spider holddown is no longer used. I believe LS engines use something similar? Not much else to report until I take them apart.

 

I removed the rocker arms on the front head as well as the cast guideplate for the pushrods. As I have mentioned previously, the rockers have a roller trunnion and the center bolt is a smaller diameter. The guideplate is a casting, maybe aluminum, rather than the hardened steel design of the previous. The inside of the valve cover and head are clean with almost no residue present. I intend to compare this mounting system to the LN3 to see if they would be compatible if a thread insert were added to shrink the thread size for the rocker bolts. More to follow on that. I did not see any appreciable wear on the rockers or the valve stem tip. 

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I then pulled the front head from the engine. The intake ports are full of junk and debris but the cylinders are fairly clean. The piston tops are dark but no huge deposits and I simply wiped them with a paper towel before photographing. I did the same for the cylinders, wiped them with a paper towel only. There is no discernable ridge at the top or scratches in the bores. The bores are stained and discolored but close inspection reveals the crosshatch is still visible. It would probably run just like it is but if this is to be put back in service, it will get a dingleberry hone job and new rings. No machine work. I didn't measure but the pistons are well below the top of the cylinder, probably .050" or more, so there is no squish or quench to enhance mixture motion. This is par for the course and the LN3 is the same way. In all other respects, these heads are no better or worse than the LN3. The only apparent difference, other than the rocker bolt threads is there is a hole in the wall that the intake bolts to to line up with the internal PCV system, the same as the L27 and all Series 1 engines. It is a simple matter to add this hole to an LN3 head. The chambers of the head are dirty and crusty and will take some cleanup to get a better handle on what shape they are in but I doubt any major problems. 

 

One other observation which has little to do with this story other than noticing the size when disassembled: The LN3 and the Series 1 engines are approx. 9.5" deck height, from the center of the main for the crank to the top of the cylinder. This is approximately the same as a 351 Ford engine, which is a relatively large "smallblock". It makes the engine quite wide, but it does have the upside of allowing a long piston rod with the 3.4" stroke, almost 6.5" long. The large rod/stroke ratio lessens the sideways force on the piston which theoretically lessens friction and increases lifespan. The Series 2 engines have an approx. 1" lower deck height, or about 8.5". That is the primary reason almost nothing is the same as the Series 1. Everything is shorter and lighter. It is also a good reason to look at a Series 2 swap even in n/a form. That lower deck height and the 3.4" stroke are almost exactly the same as the very successful 347cu in stroker for the five liter Ford engine. Not suggesting it is copied but it seems to be a very happy combination of dimensions.  

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Ronnie

Thanks for the photos. My first look inside a S/C 3800.

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2seater

Todays exploration yielded things I did not expect. Subtle differences but still mostly compatible with the previous generation. 

 

      I pulled the second head from the block and there appears to have been more moisture in one cylinder judging by a bit more rust, primarily in the chamber in the head. Again they were just wiped off with a paper towel. It seemed odd the pistons wipe off almost completely clean with no effort. More on that later. 

 

     I also removed the plastic guides for the lifters which appear to be identical to ours. I confirmed one of my extra lifters fit the guide assembly perfectly. I found the lifters had a bit of varnish on them so some took a little force to remove. I set them all aside and if the wheels look good later I will probably disassemble the lifters for cleaning and inspection. I know the photo looks like a jumbled mess but everything is in order and numbered. 

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Moving on to the bottom end, I found the oil pan was pretty beat up, which is a disappointment and it appears to remove the oil they simply poked a hole in the pan so it is essentially junk. What I did find that was interesting is there is a sort of windage tray that is sandwiched between the block and the pan. It is a separate piece that can be used over. There was no sludge or heavy residue in the pan.

 

 I noticed numbers and letters stamped on the front crank counterweight. I have never seen that before and it seemed to indicate the crankshaft had been ground undersize. When I went to remove the front main cap I saw there were also painted numbers and letters on the front side of the counterweight. After I removed the from main cap, I removed the bearing half and it is indeed .010" undersize, so I imagine the rods have been ground .030" as indicated in the note. I did not see anything terribly wrong with the one bearing I pulled. It is not perfect but good enough to run. The bearing is a Federal Mogul aluminum type which is pretty much factory. I mentioned the relatively clean pistons earlier and while I did not notice any markings indicating they were oversize, everything may have been cleaned up previously.

 

Aside from the windage tray, the one big difference from the LN3 engine is the crankshaft main caps are huge by comparison. I set one of each together for a photo and while they will pretty much interchange, even the bolts for the s/c cap penetrate further into the block. It certainly looks like it means business. 

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     I noticed it has a different style oil filter adapter that sort of curls back under the pan. I don't know if it will bolt up to ours as of yet, it would allow a longer filter without hanging below the pan.

 

I received my long 6mm bolts today so I was able to pull the crank damper. Nothing really shocking there but there is a plastic shield that covers the entire area between the damper and the front cover. It just snaps onto a couple of studs and it certainly provides splash protection for the crank sensor, perhaps its purpose, but I can see the crank sensor would need to be fitted and adjusted prior to installing the shield, a two or three step process. 

 

The oil pump drive is different but similar to ours. It has more flats than ours. The timing chain is very different. It is still a narrow non roller type, but the material for the links is thinner and there are more of them, eight vs six, so the overall width is the same. There are voids within the chain rather than the continuous surface and it is smaller pitch chain. If you are familiar with roller chain, it would be similar to a #35 chain vs our #40 relatively speaking. It has the late style chain damper which is worn perhaps .025" deep and suffers from the same alignment issues as ours. The chain is actually running slightly outside the damper and the inner part is useless. It strikes me as odd that GM never addressed the chain size and alignment even when the size and pitch were clearly changed in later models of the engine family? The real estate taken up by the drive system to the balance shaft made the cam chain narrower and pushed it outward but the tensioner was left in the original location.

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Ronnie
3 hours ago, 2seater said:

I noticed numbers and letters stamped on the front crank counterweight. I have never seen that before and it seemed to indicate the crankshaft had been ground undersize.

The automotive engine shop where I worked in another life had a crank grinder. We stamped the counter weight the same way with the undersize of bearings needed. I don't remember writing with the yellow marker but we did write on a tag we tied to it to let the owner know when he picked the crank up.

 

I remember us seeing markings on factory cranks in engines that we knew had never been torn down before too. Were the rod and main caps marked in any way to indicate how to reinstall them correctly? That's a pretty good indication a mechanic has torn the engine down before.

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I know what you mean about the markings. I didn't really examine the rods closely but the mains are stamped with a number and orientation. The stamping is too deep and perfect to have been done by hand so I suspect they were made that way? I have a set of numbers and letters and this looks way too professional. I know some OEM's have select fit pistons and bearings depending on what they measured within the standard tolerances. The reason I assume it has been reworked is it comes apart too easily and I find silicone and other unusual sealants for a 25 year old engine. I noticed yellow paint marking in a couple other places on the exterior which I chalked up to the junkyard but I don't believe they did it since the engine was in a car that was only pulled at my direction. I will get a better photo of the stamping. I want to investigate the design of the main caps too. They look so different to anything I am used to I wonder if they are factory?

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Ronnie

Stamping the rods and mains at the factory might be standard now. In the old days it was hit or miss on the factory stamping the rod to match the cap. We always checked it and stamped if needed before removing. When you get that far along it will be interesting to see if it has floating wristpiins or pressed in.

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I googled the main caps and there are sets of them on eBay, used, and they look exactly like what I have, markings and all. Same for the windage tray which appears to be a running change in the later 3800's, not just the supercharged ones. Nothing special here, just a repair for unknown reasons. I think they are supposed to be floating pins, the main difference in the s/c rods. 

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     Spent some time cleaning up today. Even with drain pans or pails it seems there is always residue that drools all over when the engine is rolled over. Cleaned tools and put stuff away for later dissection. 

 

    Today is just an illustration I was trying to describe earlier, and even then it it hard to get a good visual. The one view is of a stock intake manifold that I cut apart at the top of the runners and we added a wider sheet aluminum plenum with a removeable top. This doubled to plenum volume but the reason I post the photo is to show what our typical short ram type manifold looks like inside. The runners are straight with a slight taper to where it meets the head. Unfortunately I didn't think to backlight when I took the photo many years ago. The second photo is taken diagonally through the opening that air enters from the supercharger. It is hard to get a good shot as the runner is horizontal at best. The two white rectangles are the two runners visible from the plenum. In between the two openings to the port there is an open area with sharp straight walls. There is no effort to form any sort of inlet bellmouth to smooth flow into the runner, but instead the recessed area looks more like a flow disrupter? 

 

    The last pic is of the top of the lower intake manifold just to illustrate there is a lot going on inside this casting. The three approx. .625" round holes are for the built in pcv system. The actual valve is on the side of the supercharger above. The lower hole in the photo is where the air is picked up from the throttle body. It is routed all the way across the the casting to the left where it enters the valve cover area of the front head  through an additional hole in the flange. The upper right side hole comes from a matching opening in the rear head which is where the oil vapor is extracted. The passage in the s/c casting above this hole leads to the pcv valve itself. The last hole on the upper left is the vacuum from the intake plenum that actually powers the pcv system. Again it is routed up through the s/c casting and over to the pcv valve.  The large "D" shaped opening is a supercharger bypass that allows air to be drawn in before reaching the rotors of the s/c under low demand. It lessens parasitic loss when cruising, and idle. There is a normally closed butterfly valve in the s/c inlet above this opening, which opens under higher vacuum conditions providing a second path for air into the intake plenum. The last two small holes near the bottom are coolant openings, sealed with o-rings, that direct coolant into the throttle body casting, same as the external pipes on an LN3

      

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Ronnie
3 hours ago, 2seater said:

In between the two openings to the port there is an open area with sharp straight walls. There is no effort to form any sort of inlet bellmouth to smooth flow into the runner, but instead the recessed area looks more like a flow disrupter? 

You probably know more than I do about porting. Most of the porting I have done was on motorcycles and my experience was through trial and error. I have friends who have done a lot of it in their engine shops and they have flow benches so they can test their work. Most agree that with exhaust ports the smoother the better, but with intake ports it's a different story. They tell me if the engine is intended to produce maximum power at really high RPM putting a really slick finish on the intake runners is ideal but for engines that are intended to produce good torque and power at lower RPM, like is desirable in heavier cars with an automatic, they say you need a little rougher surface that will maintain some turbulence as air flows through the intake to the heads. All the people I know that are building performance engines are still running carburetors so I don't know if that line of thought applies to fuel injected engines or not. But if so that might explain a flow disrupter to keep the SC engine performing well at lower RPMs. The deflector might have the same effect as running a dual plane intake versus a single plane intake???

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2seater

Good points and I intend to look into other peoples experience before doing anything to it. You are right that sometimes looks can be deceiving or counterintuitive. I do have a flow bench that I will use to compare to the other intakes although flow, in and of itself, isn't the only criteria as mentioned.?

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