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Building an LN3 from spare parts plus a Supercharger


2seater
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I found the bolt in the parts manual and an actual part number, 1356635, which was a bit of a surprise. From searching the part number, the dampener pictured above was used for more than 20years up until 1990 when the change to the new style appears in the parts manual. I know my ‘90 had the old style? In any case, it is just a trivia item now. I did find a place that has them in stock for only $65.00, not a typo! This is the part 

 

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52 minutes ago, 2seater said:

I did find a place that has them in stock for only $65.00, not a typo! This is the part 

$65? WOW! 

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I found one on line elsewhere for $15.00. Just google GM part #1356635

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2 hours ago, DAVES89 said:

I found one on line elsewhere for $15.00. Just google GM part #1356635

I will look again. I would probably bite for that price. Thank you.

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One of the odd things about the V6 was that in 1967 Buick sold it to AMC and then bought it back in 1974 so are probably some odd gaps in the parts book. Might have to look under Jeep "Dauntless" also.

The really fun one was the 215 aluminum V8 which was passed around the world and a version was used in a F1 champion car.

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Thanks for the tips fellas but a couple of them I had followed up on already and I just looked again. Many of the ads are bait items with something completely different when you get there😕 The $15 bolt on one ad takes you to a used timing tab from an Oldsmobile🤔 Others take you to the site where it tells you it is unavailable. No worries, maybe some kind soul will be doing a timing chain and has one salvaged?

 

 I bought three grade eight flange head bolts for the cam sprocket. Had to shorten 1” long bolts about an 1/8” but it went together smoothly. I made certain to loctite and torque the bolts per Daves urging😜 Aside from the chain being right at the edge of the dampener, this one fit the best of any I have done recently. The curve of the face of the shoe is an almost perfect match, a big plus for wear. Front cover is now on, at least for the time being. There will be a break for a while as I have company coming for about the next week and then the heads from the donor s/c will get a more detailed examination and some light cleanup and porting. To be determined on them.

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This probably overkill but have you considered doing anything with the cam sensor magnet to make it more permanent. Like maybe JB welding it in?

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22 minutes ago, Ronnie said:

This probably overkill but have you considered doing anything with the cam sensor magnet to make it more permanent. Like maybe JB welding it in?

A very fleeting thought along those lines but that’s all. I figure they are pretty reliable, and with many years and miles of durability, I don’t expect issues within the amount of time the engine stays in the car👍  I don’t know what would help in any case. Encase it in epoxy? 

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I would just replace it as a matter of course. The plastic holder gets brittle and the magnet falls out. Easy when apart.

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It's probably not needed,  I was just thinking that a little fillet of JB weld on the cam gear metal extending up the side might reinforce the plastic housing holding the magnetic pins inside. That seems to be the area that fails and allows the magnet and/or pins to fall out. Your excellent photo of the cam got me to thinking about it. I wasn't suggesting that you do it or that it's needed.

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I am glad the word "cam" was mentioned. That is something I should do before I button up parts of the engine. I should put the degree wheel and dial indicator on it to verify the cam is correct. I have my old figures for an '88 cam, which is in my original '90 engine, but this is a brand new Clevite replacement based on that spec. so it should be checked before calling it good. Good project for tomorrow.

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The cam checks out as ‘88 spec. Plus .015” to .020” additional lobe lift 8-10 degrees more duration. ‘88 cam is symmetrical, same lift and duration on both lobes vs different lift and duration on each lobe for ‘89/90. Tiny differences but but new cam vs used and more accurate degree wheel and different indicator(digital). I actually prefer the old analog dial indicator for this purpose. Hard to sneak up on the lift measurement with a digital but easy to see the movement of a needle. Hard to get smooth rotation with a breaker bar against fresh bores and rings. A fair amount of “stiction” 😖

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Good looking degree wheel. Looks like it would be easy to read. Do you find TDC with that dial indicator or with a piston stop? In the old days we considered a piston stop to be the most accurate but I don't think it would really make much difference. I assume the measurements on this roller cam are taken a 0.050" lift like flat tappet cams?

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Yes, piston stop. In this case it is pretty easy even with the head off since the pistons are above the deck at TDC, and remain so for 15deg of crank rotation. Yes, the duration is at .050” lifter rise.

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Returned to do a little more on the assembly and first thing I find is the crank sensor design changed at some point and the brand new one for an ‘89 is totally incorrect for the ‘95 damper, photo below. Investigating via Rock Auto, it appears the design changed for the ‘93 model year. I thought it might be peculiar to the S/C variants but that turned out not to be true. There were S/C engines beginning in ‘91 but the crank sensor was the same as the LN3 up through ‘92. The late model is larger physically, one piece plastic, non adjustable and the sensor spacing is much wider. It does use the same mounting pattern as all others.

 

 I tried to get a photo of the timing chain damper to show how close it runs to the back of the oil pump. Not the best but hard to see when assembled through the bottom of the front cover.

 

Photo of the ‘95 heads with just a little wire brushing in the chamber and ports. They don’t look appreciably different than any other prior to the Series II. The exhaust seats look pretty wide, which is pretty normal for a Buick but these look wider than normal. Hopefully they are usable without a bunch of rework. 

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1 hour ago, 2seater said:

totally incorrect for the ‘95 damper

Good photos. I'm learning a lot from them. Have you checked to see if the '95 damper is straight or tapered inside? If you haven't done so I would spend a little money and have those heads Magnafluxed for cracks or buy a dye kit and check them yourself before doing much to them.

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I cleaned up a few valves at random and found them to be pretty worn with little margin left. The exhaust shown below is total junk with severe pitting. I have a few new intake valves, EngineTech and Sealed Power, most of which have been experimented with, primarily the back cut. The unmolested Sealed Power on the left with the EngineTech to the right compared to the used valves.

Surprisingly, the seats aren’t too bad and dropping two new and a used intake valve into the heads show the stem heights to be spot on.

Valves are inexpensive but a bigger issue is the valve guides. Five of the six exhaust guides are pretty good, however, five of six intake guides are awful. Time to check with the machine shop on possibly repairing. Any L27 head prior to 1995 would work but the remanufactured supply appears pretty thin or way overpriced. Failing that, I have my original untouched 1990 heads with 100k on them. They can be modified fairly easily to work with the internal pvc system by drilling one hole in each intake face. Oh well

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Well, a short update from this morning, which sort of sums up the slow moving nature of this project🙄 I found the machine shop I have been using for many years has closed and the owner retired, approximately two years ago. I think the Covid effect has distorted the real and perceived passage of time? He left a list of alternative shops on the door and I stopped by one I haven't set foot in in probably two decades or more. The funny thing about that is that it looked about the same. It is attached to a large FLAPS that has been in business ever since I can remember, although it has changed affiliation over the years. It is a Federated parts store now. I had a nice conversation with a young guy discussing approximate costing to crack check, install new valve guides, new valves and a valve job. Approximate estimate of $650. From my looking at the heads prior to taking them in, they appear to have bronze liners already installed. He offered to make a few calls to see if any remanufactured heads from the correct time frame that might be available. 

 

I guess it is time to disassemble the original heads from my '90 to see if they are in decent shape. Before making any more conjecture on that, I will examine them. 

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2 hours ago, 2seater said:

I had a nice conversation with a young guy discussing approximate costing to crack check, install new valve guides, new valves and a valve job. Approximate estimate of $650. From my looking at the heads prior to taking them in, they appear to have bronze liners already installed.

That's a lot of money. When I was working in the automotive machine shop most worn valve guides could be knurled instead of installing new ones. Also a valve was rarely replaced unless it was bent or had other damage like worn keeper groves.  Maybe things have changed since I was doing that type of work. Maybe now days they consider things like knurling the guides taking a short cut. I don't know, it's been a really long time ago.

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