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Building an LN3 from spare parts plus a Supercharger


2seater
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I decided to make this a standalone topic, even though somewhat similar threads have been done in the past. This has been very slow moving, years in fact, but I am at an assembly stage now. I copied the text below from yesterdays entry in "what did you do etc.."

 

Finally got the heated part of my garage, my winter shop space, cleaned up and organized enough to pull out the 1988 block I got from Daves89. I have mentioned this future project before, but to synopsize:  The block had very low miles, ~5k, but it had severe internal rust damage to the heads and block, which was seized up. I couldn't leave well enough alone and had the block bored .030" oversize, and the worst cylinder was offset bored to save it for a future supercharged project, which has been languishing for years now. I intended to buy the parts from an s/c engine but as luck would have it I acquired and entire complete 1995 s/c engine in which I detailed the teardown in a previous thread on this forum. If I had purchased the s/c engine prior to the work I had done to the 88 block, I would have abandoned the 88 and put the money into the s/c engine, but that's water over the dam now. I intend to go ahead with the transplant supercharger on the 1988 block, a true winter project.

 

My intention is to use up leftover parts and parts from other engines to wind up with something that works. The last full day was looking for bearings, freeze plugs, measuring the crank journals etc. I found two half sets of King brand main bearings, one set standard and one set .001" under. I had used the other half of the two sets on a previous engine for the purpose of tightening up the clearance by a half thousandth. In this case, the crank, which I think may be Daves from his 89, is almost spot on spec, even after polishing, so it is hard to say if the slight undersize will work out or not. I found a complete set of what looks like ACL rod bearings but they are made in China so they are probably clones. I still have the box for the bearings I actually used on the last engine which are genuine ACL made in Australia. Also I had a previously installed but never used Enginetech cam bearings. I don't remember why I removed them after installation but they are now installed in the 88 block and I also trial fit the new Clevite 1988 spec camshaft, which turns freely. Feels pretty good to be finally moving forward. 

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Not a lot to report on second day of work, other things to do of course. I ordered a new oil pan today, a Dorman replacement. The S/C engine from the junkyard was fairly dinged and dented but the worst was they simply poke a hole in it to drain the oil 🤨, plus I think the pan is slightly different in any case. I also picked some Plastigage to verify my amateur measuring skills. One variety pack in the entire store. Pretty obvious that old traditional FLAPS are fading away.

It looks like I need two more 1.5" brass frost plugs for the block, I only have four on hand, plus I need two of the little 5/8" ones for the front of the main oil galleries. I did get the crank set in the block, just to check clearances at this point. I only did the mains today but they came in very nicely at .0015"-.0017" of clearance using half a set each of standard and .001" under bearings. The one big plus for Plastigage as a double check is the ability to show how square the journals are. Any taper across the journal shows up immediately. 

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Thanks for starting a new topic for this. I'm going to enjoy reading about what you do to get the SC engine assembled and installed in the car. It's something I've always wanted to do with my Reatta but probably never will. Well, maybe if my engine ever gives up. Following your thread will prepare me for what I would have to do if needed.

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2 hours ago, Ronnie said:

Thanks for starting a new topic for this. I'm going to enjoy reading about what you do to get the SC engine assembled and installed in the car. It's something I've always wanted to do with my Reatta but probably never will. Well, maybe if my engine ever gives up. Following your thread will prepare me for what I would have to do if needed.

As I mentioned, it will be slow moving, but I have promised myself I would spend time on this for a couple of winters now. On the plus side, all of the machine work has been done (I think). I may be missing some bits and pieces. My fallback position is for it to revert to n/a operation just by reinstalling the brackets and accessories from the n/a engine. The entire rotating assembly was balanced using a new damper for an s/c engine, twin belts, but the inner one is in the standard location so it will work in a non s/c application. Hmmm, I'll bet you could drive a ProCharger with a jackshaft using that second belt drive🙄

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Will the SC engine you are working on need dished pistons like most SC engines do or is there a work around that allows you to use pistons from a NA engine like mine?

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10 hours ago, Ronnie said:

Will the SC engine you are working on need dished pistons like most SC engines do or is there a work around that allows you to use pistons from a NA engine like mine?

All 3800 pistons are dished to the best of my knowledge. Compression ratios varied a little from about 8.5:1 to 9:1, maybe a bit more. The LN3 is 8.5:1 and even with a dished piston, it sits below deck .040-.050" or so. It is why I recommend using the later model 1993 L27 pistons on a rebuild to get the piston to approx. zero deck and around 9:1. The combustion chamber in the head is small, about 38cc IIRC. I don't know exactly why that is, but the valve angle to the bore is only 10deg, so with all the generous spacing, it is a non-interference engine. I don't know of a flat top stock type piston to fit an LN3 but you can get close by using a Ford 3.8 piston from around the turn of the century, with the appropriate overbore, yields over 11:1. The Ford has the same piston pin diameter and offset in the piston. The bore is something like .011 larger than the Buick so there are many possibilities. Maybe a dedicated E85 engine?

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Interesting. I thought all SC engines needed special pistons.

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8 hours ago, Ronnie said:

Interesting. I thought all SC engines needed special pistons.

They aren't special per se, but they are different, judging by what I found when I tore the donor engine down. The pistons are dished, pretty much the same as all others, but the pistons and rods are full floating type, with retaining rings in the pistons to retain the piston pin, they are not pressed in the rod. The thrust sides of the s/c pistons appear wider or flared out ostensibly to provide greater load area and the rods do appear to be a bit beefier. This was a 1995 engine which was the last year of the Series 1 s/c, so I do not know if earlier years are the same or not. I have a photo somewhere.

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This is a pic of the s/c piston on the right vs an LN3. If you look closely the skirt on the s/c wraps around the side more fully and you can see the retaining ring inside the pin hole.

553BCF7A-E449-4BE0-9565-F9C089661244.jpeg

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Small progress today. I decided to at least try the rod bearings for fit and clearance. I wonder if I bought them on a clearance sale or something? They were never unsealed from the plastic inside the box. As near as I can tell, they are a clone made in China. I measured them and the overall width is correct but they have a very slight chamfer on the edges where they bear against the journal, which reduces the bearing surface even so slightly, maybe .010". The Buick uses a narrow bearing, much narrower than the big end of the rod, and only .065" wide. I think part of that is the split pin crank where each rod has its own journal and there is a rolled fillet on each side of each journal for strength. Rod side clearance isn't very great but you never want the bearing to be able to overlap the fillet area. I did check #1 (.0018") and #6 (.002"), which is well within tolerance so I will probably go with them to use them up. A quick search of Rock Auto and a couple local FLAPS shows standard size aluminum bearings are out of stock. Undersizes are available, but not what I need. This being a BUICK V6, the main bearing clearance range is tighter than the rods.

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I checked my engine parts inventory and I have a flywheel and partial upper engine gasket set. Yours if you want them...

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1 hour ago, 2seater said:

As near as I can tell, they are a clone made in China.

They will probably be fine but I think I would try to find some Clevite, Federal Mogul or Sealed Power for a crucial part like bearings. But  who knows? They might be made in China now to.

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Thanks for the input. You are likely right about the country of origin being a fluid thing. It isn’t so much I am concerned about Chinese parts, they can manufacture to specifications. It is the deliberate mimicking of a known brand, including the packaging, that causes the question. If they all end up within spec I am going to use them.

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I checked the remaining four rod bearing clearances and they all came out between .0018"& .002", so all are good to go. The variations followed closely the small differences in my micrometer measurements from journal to journal. This the third stock LN3 crank I have measured in the process of my various projects and have yet to find a problem with any of them. This is in contrast to the S/C donor engine that I tore down which had been rebuilt once before and the mains were .020" under and the rods .030". Must have led a hard life.

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Small item today about what I had mentioned previously about an oil pan. The one from the supercharged engine was damaged so there was no chance to reuse it on the new build. My research using Rock Auto to find part numbers was a mixed bag. I used a 1990 as my search year since that is the car it is being installed in. This gave me a suggested Dorman part number but was lacking detail on a view of the pan regarding the oil level sensor. I checked with my local Advance Auto parts and the pan was available to order for the same price. I was sort of hedging my bet a little. As it turned out, the pan came in without the sensor opening. We looked at alternatives on their computer and pans that didn't have quite the right shape showed up as well, so I had them hold the pan while I investigated. I dug out the pan from the s/c engine and it had the shape of some of the different pans on the FLAPS computer. I plopped it on the block that is being assembled and it looked like that style would fit with no issue. Going around the bolt pattern it all looked good until I got to the rear two bolts by the transmission. The spacing of the bolt holes was different by 1/2". I do not know why or if that is done on purpose, but I am pretty sure it is because the L27 engine, the first true Series 1 3800, has a one piece crankshaft rear oil seal. That also caused me to look further since I saw small differences in the depth of the pan listed in the catalogs. Hmmm. At a glance, it doesn't jump out, but the S/C pan is one inch deeper than the LN3, even though the capacity is listed as 4.8qts, same as the LN3. I am sure the different shape is the reason for the similar capacity even though deeper. That would have been bad. The oil pickup should be 1/4"-3/8" off the floor of the pan. In 1990 there were potentially three different 3.8 liter Buick V6's in production, and were used in different car lines. I think this is what has confused the catalog listings that don't differentiate the various car lines even though it is part of the sorting process?? In any case, if I enter 1989 as the model year, the available suggestions changes to only two, and neither are a Dorman. I saw the Spectra listed on Rock Auto, which clearly stated it had the sensor hole, and I back checked with Advance, which also showed the Spectra pan. The difference was Advance's pricing was over $30 more than Rock Auto, which was a surprise since the Dorman pan was the exact same price. I figured I would just return the Dorman pan and buy from Rock Auto but I was surprised when the Advance Auto manager reduced the price to match what I had already paid when I explained the situation, a pleasant surprise.

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The 3800 is such a generic type of engine I'm surprised they made more than one pan.

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45 minutes ago, Ronnie said:

The 3800 is such a generic type of engine I'm surprised they made more than one pan.

I agree, it came as a surprise to me as well. It was used in some rwd cars, Camaro?, but that wasn't the circa 1990 era unless I am way off base. If I can add and edit a photo in from my phone I will show you what I mean. The last of the Series 1 engines was the L67 of 1995, and this one came out of a Riviera. I have no idea why the front part of the pan is raised up where the LN3 is pretty much square. The exhaust crossover and things like that wrap around the back and over the bellhousing area, same as ours? I know it is a lousy photo but I was concentrating on the level sender at the time, which is a different type than ours.

B91C593F-71DB-4AEF-89FB-7473D68F6D56.jpeg

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Checking and adjusting piston ring end gaps today. Normally it is a cursory look to be sure the set is sized correctly and not mis boxed. In this case since I am using hypereutectic pistons, the top ring gap is suggested to be 40% wider. The piston absorbs less heat than a standard cast piston which puts more heat into the top ring, especially as this one will be boosted. The FSM gives a specification of .010"-.025", for the top and second ring, an awfully large range. In the absence of a specification, a general rule of thumb I have used based on multiple sources is .004" per inch of cylinder bore or .01532" for the 3.830" bore. As it turned out, the second ring is a loose .016" for all six, so they are considered good to go. The top ring was in the same range so I opened up the end gap to .021" on my little hand cranked ring grinder and called it good. The rings are nothing special, Hastings steel/moly top and second with stainless steel oil rings. The top ring is also a little thinner, 1.2mm vs the LN3 1.5mm, since the pistons are a newer model. 

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I love these threads you do @2seater. Very interesting. This is what ROJ is about.

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Small things over the last couple of days but not much actual progress. I sorted through miscellaneous parts bins and realized I do not have the drive gear for the balance shaft, the one that sandwiches behind the cam sprocket. I have the one for the S/C donor engine but the camshaft drive is different for the Series 1 engines and newer, so it won't work. I found one on eBay which I had to overpay for, but as I found later, Rock Auto is out of stock and GMParts Direct doesn't even show the part on their exploded view so I had no part number to search with. I toyed with the idea of simply eliminating the balance shaft drive but decided to keep that original. 

 

I did install the rings on the pistons and started a final cleanup on the block. I use rifle and shotgun cleaning rods, brushes and patches to go through the oil passages, crankshaft drillings and anywhere I can access. 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 but that brings up another unfortunate sign of the times. I only need two 1.5" shallow brass frost plugs and two 37/64" steel oil gallery cup plugs for the front behind the cam sprocket. I tried all the local FLAPS within a mile of my house, O'Reilly, Autozone, Advance and NAPA and not a one of them had anything. A couple places even pulled out the box with leftover and homeless parts but no joy. That oddball size to the oil galley is the tap drill size to tap the holes for 3/8"npt screw in plugs like are used at the rear of the block. I could tap the holes, but it then requires special shallow npt plugs so they seat below the block surface and not block the right angle oil feed passage behind the hole. The camshaft flange partially overlaps these passages so nothing can extend outwards. I have been forced to order an entire plug kit online, where I will end up with the same selection of spare parts, GRRR. Supply chain or just not economically possible to stock for obsolete vehicles??

 

The above has caused a bit of a delay until I receive the parts. I could install the crank and proceed with the pistons but I prefer to do the cam while I can access it inside the block with the block inverted. Impossible to do with the crank in the way. It is probably a good time to clean the parts I will be reusing from the 1995 donor engine, which will have to be done eventually. I haven't opened up my solvent wash tank in over three years, so I guess it is time to see what monsters lurk within. It sounds simpler than it is. I have a small, heated area I work in during the winter. To conserve space some seldom used items are hidden or nested together. In the case of the wash tank, it rolls between the legs and under the cross beam of my homemade 20ton press. The press stands approx 18" out from the wall which is lined with shelves from four feet and higher. The wash tank extends back to the wall so it is approx. flush with the front of the press. Over time, a horizontal surface tends to fill with "temporary" resting place items if you get my drift.

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