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Building an LN3 from spare parts plus a Supercharger


2seater
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1 hour ago, 2seater said:

The block had been hot tanked but there are always odds and ends that appear afterwards. All of the sheet metal plugs and pipe plugs are out of this engine for cleaning

Brings back old memories. the following is a little off topic but I like to reminisce abut the old days sometimes. 🙂 

 

At the first garage I worked at it had an automotive machine shop in the rear of the building. One of my primary jobs when I first went to work there was tearing down engines and putting parts in the hot tank (and the cold tank) and getting them out and cleaning them. Your way of scrubbing the passageways out with bottle brush like tools is best but I don't recall us ever doing that. We cleaned the passageways a different way. I would take them out to a covered concrete pad we called the patio to clean them with really hot water under pressure. 

 

The owner had built a hand held cleaner that was much little like a steam jenny wand. It was a length of heavy steel tubing (pipe) about 5 feet long that had the last 6-10 inches bent down at about a 45 degree angle with a large nozzle attached. On the other end of the pipe was a shutoff valve attached to a large hose that went to a dedicated hot water heater that was set at a really high temperature. Below that pipe was another pipe that paralleled the hot water pipe and intersected it at about a 45 degree angle near the end of the hot water pipe where it was bent down. The air pipe had a valve at the end that when squeezed added high pressure air from our big air compressor to push that hot water out the nozzle. It was one hell of a cleaning machine that cleaned everything, including the passageways, but most of the stuff it blasted off, along with a lot of hot water, ended up on the operator. That is the reason that job was given to the new guys like me. The owner thought that job was a good test to see if you really wanted to work in his garage. I passed the test and went on to learn a lot from him.

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Good story Ronnie and and interesting read from 2seater. Thanks for posting guys...

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No such thing as off topic in this thread. I know this is a Buick parts problem but I am sure it exists for other makes as well. Repairing things is getting to be a thing of the past. Partly it is parts cost but a big one is the cost of the labor involved. If you do things yourself, you save that labor, but if the parts aren't available, that goes out the window. We had a fairly long discussion at the NAPA store, and he mentioned even mainstream and popular items, like a rebuilt 5.3liter LS engine for pickups has a five month waiting list. Some is a Covid effect on parts shortages, but in this essentially orphan engine case, it just piles on top. 

 

I did go out and unlimber the parts washer tank. Lo and behold, the pump kicked in and proved to be none the worse for sitting dormant for years. I did a basic cleanup on the front cover from the S/C engine and I am hoping to use it on the '88 block but there are some things that don't look quite right. It may be just the oil filter adapter which is a real oddball, and I will take a pic when I get a little better mockup. 

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Waiting for parts so a good time to clean and sort a bit more. Everything that came from the s/c engine is a grimy mess but the front engine cover was my main item for the near term. It cleaned up fairly well externally so I could trial fit it to the older block and that turned out to be a non-issue. It bolts up with no issue but the oil filter adapter is so different I thought maybe the cover casting was different. The filter adapter kind of curls back under the engine a bit possibly explaining the cutaway at the front of the S/C oil pan? I do not know if it will clear the stock pan until that gets here but it may be a moot point anyway. I have an oil cooler adapter that sandwiches between the filter and the adapter pushing it even further inwards. 

 

There is a plastic ring shaped splash guard that surrounds the area between the balancer and front of the engine. I imaging they felt they needed more protection for some reason and it could be added to an earlier model if desired. It just snaps on to three of the front cover bolts that have a small extension on the head of the bolt. Maybe it would be helpful keeping splash from the crank sensor area in freezing weather??

 

The one area that is a bit of an issue is the oil pump drive. The oil pump is similar but the drive, which is part of the timing chain assembly, has six equally spaced drive lobes that engage the oil pump gear in the front cover. The LN3 oil pump drive is two flats on the lower sprocket. This drive also contains the crank sprocket for the timing chain. It wouldn't be an issue if I could simply swap the S/C drive onto the earlier crankshaft. While it does fit the crank and the timing mark is the same, the pitch of the timing chain is quite a bit different. The later timing system uses a smaller pitched chain. If you are familiar with common roller chain, it is like #35 chain vs #41 chain on the older engine. The only solution I can see is to change the oil pump inside the front cover by installing an oil pump repair kit with the correct two flat drive.

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Edited by 2seater
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As time goes on I'm afraid it is going to get a lot harder to get parts for out old engines. I'm starting to see by your posts that there are more differences in the SC engine than I expected there to be. I would have thought timing chains and sprockets would have been the same.

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1 hour ago, Ronnie said:

As time goes on I'm afraid it is going to get a lot harder to get parts for out old engines. I'm starting to see by your posts that there are more differences in the SC engine than I expected there to be. I would have thought timing chains and sprockets would have been the same.

All true. I am mildly concerned the oil pump gears themselves are thicker than the LN3, which will mean I need to find a good front cover specifically for the LN3. I am not sure why the cam and oil pump drive would be beefed up either? None of that is impacted by the supercharger, so it is a mystery. The little chain damper shoe is the same. Maybe I threw away my parts car too early/

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1 hour ago, 2seater said:

I am not sure why the cam and oil pump drive would be beefed up either? None of that is impacted by the supercharger, so it is a mystery.

Could more a higher volume oil pump be needed on the SC engine to supply bearing lubrication and maybe cooling for the supercharger? I've never saw one of them before so I'm just guessing at what the reason might be.

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2 hours ago, Ronnie said:

Could more a higher volume oil pump be needed on the SC engine to supply bearing lubrication and maybe cooling for the supercharger? I've never saw one of them before so I'm just guessing at what the reason might be.

Beats me as well. The supercharger is completely stand alone with no cooling or oiling connected to the engine itself. There were no oil squirters or piston cooling jets. Maybe it is just a running change that applies to all newer model engines?

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1) are many oil filter adapters for different installs, 3800 was used by every car line (Cadillac had a 4.1).

2) LN3 is spec'd at 40 psi oil pump. L27 and later, 60 psi.

3) Is something niggling about the L67 intake manifold gasket.

4) Before the LN3 3800 (balance shaft) there was a 3.8/231 that dated back to the 60s. Many different models.

5) Should be millons out there.

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I was thinking about the possible oil pressure difference but did not look into it. I did notice the oil pump repair kit that I ordered has two different springs and pistons used to set the base oil pressure, so there certainly seems to be a possibility. Why that would require a finer pitch chain, I still wonder

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I guess I won't really know until the oil pump parts arrive, but a search of Rock Auto reveals when the change took place. While it is by no means definitive, it appears the oil pump changed in the 1995 model year. Up through 1994, the same oil pump as in the LN3 was used in both the N/A and S/C engines. I am pretty sure that 1995 is when the change to the Series II engine took place, but only the N/A variety. The S/C version was still the Series I style until 1996. Looking at oil pump repair parts yields the same part numbers for both the N/A and S/C variants for 1995. There is no information on the thickness of the gears but the tooth count of the inner gear of the pump is exactly the same as all prior years, (11). My best guess is the oil pump drive and timing set was changed for some reason to do with the Series II engine which is more compact than the Series I, and the S/C engine for that overlap year was changed for commonality of parts?? 

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If you wish to have a higher oil pressure, all you have to do is shim the relief spring with a small washer.

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Changed earlier than that for some, my 92 TranSport had the L27 and 60 psi oil pump. Also had a different oil pressure sender.

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Used balance shaft drive gear, set of expansion plugs and the repair kit for the oil pump arrived today. The only things I used from the expansion plugs today were the two small steel ones, 19/32" from the stamped markings, which allowed the camshaft to be installed to stay. A couple more of the larger water jacket brass plugs will be used later.

 

Now that the cam was in for good, the spare balance shaft was installed and it mated perfectly with the used drive gear. The one item I didn't have in my misc. parts was the retaining bracket for the balance shaft so the '95 s/c donor engine gave up its retainer which fit perfectly to the '88 block. One item I think I have somewhere is the sheet metal "spider" that covers the balance shaft inside the engine valley and has fingers between the various pairs of valve lifters. The fingers keep the metal dogbone style lifter aligners in place. The '95 engine uses one piece plastic guides for each side of the vee. It looks like modern plastic piece will work instead but I prefer the metal cover which keeps any oil flung off of the balance shaft from the bottom of the intake manifold . I will post a photo later if I can find the piece to illustrate the difference.

 

The last item of some concern was the oil pump drive. The repair kit comes complete with the two gears, a new cover plate w/fasteners and two different style oil pressure springs and plungers. According to the paperwork with the kit, it depends on the style of the front cover as to which spring and piston are to be used and that will come later as they are installed under the oil filter adapter outside the engine proper. The new gears are a complete drop in replacement with the correct drive style to mate with the crankshaft sprocket for the timing chain. Problem solved. Hard to see but these are the two different oil pump gear sets.

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Edited by 2seater
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Since I do not have a spare sheet metal spider type lifter guide retainer I mocked up the late model plastic "glove" type from the '95 donor engine. It fits perfectly and when installed, it completely surrounds the protruding part of the lifter that has the two flats for the guide. When installed, the lifters are not visible at all. The photo below is of two lifters in place with the standard dogbone guide that the sheet metal spider retains. Above them is the one piece plastic guide assembly. There is also a photo of a disassembled roller lifter taken when I went through a set destined to be used on this assembly. There really isn't a lot inside so they are fairly easy to take apart and clean and check for smooth operation of the sliding piston inside. Tolerances are tight. Total internal travel is approx. .125".

 

Not much else was done today. My intention was to install the crank so I could start assembling the piston/rod assemblies in the bores which will be final scrubbed and cleaned as each one is installed. I have odds and ends of seals and gasket as well as complete sets. The gasket sets are still sealed up and I did not expect to find none of the sets contained a two piece rubber rear main seal. I have three sets of rope seals, but no rubber lip seals which I have better luck with. I know the rope seal can work and the basic engine was designed for them in the past, but...Maybe a local jobber will have one but I have my doubts.

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The crosshatch looks good in the cylinders. Did you do that yourself? Do you have to install the lifters in the same order they came off the cam like with flat tappet cams or can you mix and match the roller lifters?

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5 hours ago, Ronnie said:

The crosshatch looks good in the cylinders. Did you do that yourself? Do you have to install the lifters in the same order they came off the cam like with flat tappet cams or can you mix and match the roller lifters?

This block is from Daves89 and is the low mileage '88 vintage that had the rust and water damage in the cylinders as well as some intake valves. It was supposed to be a 5k mile engine but poor storage killed it. I found it was relatively well sealed up but someone had removed the pcv valve allowing water inside. It has been bored .030" oversize at a local machine shop.

 

The roller cam and lifters can be interchanged although I do tend to keep them in order if I am going to reassemble the same parts, of course the lifter could still be spun 180deg, the flats on the upper end are symmetrical. I have a lot of stock lifters and I check the roller wheel for chips or flaws as well as how the wheel feels on the axle. Also, in this case, I have installed a brand new cam, with the 1988 spec. lobes. 

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Here is annoying quality issue. I had to purchase a new timing chain damper because the last one I had in my spare parts is assembled incorrectly. The shoe that bears against the chain is installed upside down. The photo below is a proper damper on the left and the bad one on the right. The arm for the spring that tensions the shoe is supposed to fit into a cut out space on the back of the shoe so it bears against the steel pivot pin for the shoe. The shoe isn’t exactly symmetrical either. The taper on either end is different and the pivot point is 1/8” off center.

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As I imagined, there were no rear crank seals at the couple of places I tried but NAPA will have it tomorrow. In the mean time I gave the block a little basic black paint and installed the brass water jacket plugs so it looks like a less neglected block. 
I also reinstalled the plug for the main oil passage to the block. There is a pipe thread type plug that screws in under the knock sensor. The plug pictured below, installs about one inch into the passageway to block oil from contacting the knock sensor. I don’t know if that would do any harm but it sure would be a giant leak if the engine is started with the knock sensor removed. It is a 1/4” straight pipe thread with a 1/4” Allen socket head. 

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47 minutes ago, 2seater said:

It is a 1/4” straight pipe thread with a 1/4” Allen socket head. 

I wouldn't have thought about there being a passage way behind the knock sensor that needs to be plugged. Was that passageway used for another purpose during the machining process of the engine block at the factory?

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