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Restoration of BringaTrailer 240z - HLS30-35883


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Posted (edited)

The English differential carrier for my Japanese car has arrived!

IMG_20210310_181844.jpg  IMG_20210310_181909.jpg  IMG_20210310_182031.jpg

The 4.11 differential has been dis-assembled:

IMG_20210302_223018.jpg

 

My plan at the moment is to strip, prime, and paint all of the gloss black enamel parts of the car that haven't yet been painted... in one day!  That will require suitable planning and space.  I am thinking I will wait until I am 100% done with the car body work and have carted it off to the paint shop.  That will free up a lot of room in the garage. 

The list of items is extensive:

  • front crossmember
  • front control arms
  • front compression rods
  • front strut housings
  • front strut springs (both stock and aftermarket)
  • front strut upper spring seat
  • front strut upper mounts
  • front ball joints
  • anti-roll bar
  • anti-roll bar mounting reinforcement plates
  • anti-roll bar mounting brackets
  • steering knuckles
  • steering arms outer (already painted)
  • steering rack housing
  • steering rack mounting brackets
  • steering rack u-bolt brace
  • steering shaft with u-joint
  • front wheel hubs
  • front differential crossmember - diff and front suspension mount
  • differential limiting strap brackets
  • differential rubber isolator mount - front
  • differential rear mount - mustache bar
  • differential rear mount - mustache bar washers with bonded rubber
  • differential case
  • differential front flange to driveshaft
  • driveshaft (already painted)
  • rear suspension crossmember - rear suspension mount
  • rear suspension vertical supports
  • rear suspension brackets - control arms to vertical supports
  • rear suspension control arms
  • rear axle shafts
  • rear axle shaft - inner flange to differential 
  • rear axle shaft - outer flange to axle/hub 
  • rear wheel hubs
  • rear brake backing plates
  • rear strut housings
  • rear strut springs (both stock and aftermarket)
  • rear strut upper spring seat
  • rear strut upper mounts
  • engine oil pan
  • engine mounting brackets
  • engine mounting isolators
  • transmission mount
  • transmission mounting isolator
  • clutch slave cylinder
  • handbrake handle assembly (partial)
  • radiator
  • gas tank
  • driveshaft (already painted)
  • seat frames lower
  • seat backs upper
  • pedal box (already painted)
  • clutch pedal (already painted)
  • brake pedal (already painted)
  • gas pedal
  • brake booster one way valve mounting bracket
  • brake booster
  • mud guards inside front fenders
  • hood tension rods
  • front tow hooks
  • rear tow hooks
  • battery upper frame

Then again, maybe I will do a couple of batches - it might be easier in the long run!

 

 

Edited by inline6
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  • 2 weeks later...
On 12/1/2020 at 7:06 PM, inline6 said:Combustion chambers were touched some as well, including mild undercutting of the chamber edges to improve flow around the valves at lower lifts. 

This combination of changes was done to attempt to match the camshaft, to take advantage of the higher lift and larger intake valve.

  IMG_20201201_212109.jpg

IMG_20201201_212131.jpg  IMG_20201201_212145.jpg  IMG_20201201_212156.jpg

 

Are you also eyebrow notching the cylinder block deck to unshroud the valves?

Edited by Racer X
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Posted (edited)
22 hours ago, Racer X said:

Are you also eyebrow notching the cylinder block deck to unshroud the valves?

Hmmmmmm.  I chose not to do that for this engine.  Prompted by your question, I did some researching of eyebrow notching the L24.  I found that some people's L24's had valve to block contact.  I became a bit concerned that I missed a required modification to keep the larger exhaust valve (or the intake) from hitting.  I found a couple of relevant threads:

 

It looks like I should have checked mine out specifically for clearance issues.  The head has been bolted and torqued with a new Nissan gasket at this point.  I don't know if it can come back apart without replacing the gasket.  Kind of a pain...  So, my block is bored .030" over which is more than the .5mm Carl mentions.  From a valve clearance standpoint, I am probably ok.  That said (and I will attempt to verify as best I can without removing the head), is it highly beneficial to do?  

Edited by inline6
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Well, thanks @Racer X for getting me to look at this closer.  I continued looking at pics and reading through some old posts and I see a problem that I did not before.  Coolant holes in the gasket are not to my liking.  My head gasket:

11044-27L01

My block and head:

IMG_20190412_183113.jpg  IMG_20190413_164305.jpg  IMG_20201201_212013.jpg

 

A Nissan Comp MLS gasket:

11044-E4623

 

So, at this point, I don't feel good at all about the gasket I used.  I should have checked the coolant holes.  It seems best to pull my cyl. head off at this point.  I still have the issue of pistons above the deck by .025" and all the thoughts shared earlier in that regard.  So, will have to see about how best to proceed.  First step is to take the head off.

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8 minutes ago, inline6 said:

Well, thanks @Racer X for getting me to look at this closer.  I continued looking at pics and reading through some old posts and I see a problem that I did not before.  Coolant holes in the gasket are not to my liking.  My head gasket:

11044-27L01

My block and head:

IMG_20190412_183113.jpg  IMG_20190413_164305.jpg  IMG_20201201_212013.jpg

 

A Nissan Comp MLS gasket:

11044-E4623

 

So, at this point, I don't feel good at all about the gasket I used.  I should have checked the coolant holes.  It seems best to pull my cyl. head off at this point.  I still have the issue of pistons above the deck by .025" and all the thoughts shared earlier in that regard.  So, will have to see about how best to proceed.  First step is to take the head off.

When I build a bottom end for the E31 head I use on my race car I eyebrow the cylinders for valve clearance and to unshroud the valves at maximum lift. I do it before any bore honing or boring, so I can see how far down the bore the upper limits of the piston ring travel is ( you don’t want to go that far down).

After I cut and polish the eyebrow, I assemble the crank, a piston, the head with cam and valves for that cylinder with clay on the piston top, to check my work. I don’t recall the measurements, but it is clear that with larger valves this work is required to prevent valve to cylinder contact and unshroud the valves adjacent to the cylinder walls. It also gives me an idea how close the valves come to the tops of the pistons.

 

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I put a N47 head on my 2.4 block. Chucked up the valves and spun scratches in the smaller bore block. Notched them then used clothes line wooden pins to hold the larger valves in place on the N47. Put it back on then unclipped the pins letting the valves drop without any contact. Worked good and gave me some quality drinking time in the coldest of winter. Provided but not required. Like I need an excuse to drink!

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Alright then.  I took the head off today.  The head gasket didn't stick to the block or the head, so I think it is reusable.  After I got the head off, I went to work on modifying the gasket.  

IMG_20210321_122317.jpg  IMG_20210321_122337.jpg

 

I used a washer with a 1/4" hole to guide the drill bit.

IMG_20210321_123902.jpg  IMG_20210321_130746.jpg

 

With the gasket modified, I turned my efforts on eye-browing the block.  Hopefully, I have not royally screwed up here.  I removed the timing chain, rotated the crank to get the pistons below deck, and then covered the block with a plastic bag, and cut out the top of it so I could access the tops of the bores.

piston 1 - pic taken from passenger side - front of piston is toward the top of the pic:

IMG_20210321_211759.jpg

piston 2 - pic taken from passenger side - front of piston is toward the top of the pic::

IMG_20210321_211803.jpg

piston 3 - pic taken from passenger side - front of piston is toward the top of the pic:

IMG_20210321_211807.jpg

piston 4 - pic taken from passenger side - front of piston is toward the top of the pic:

IMG_20210321_211817.jpg

piston 5 - pic taken from passenger side - front of piston is toward the top of the pic:

IMG_20210321_211824.jpg

piston 6 - pic taken from passenger side - front of piston is toward the top of the pic:

IMG_20210321_211831.jpg

piston 1 - pic taken from driver side - back of piston is toward the top of the pic:

IMG_20210321_211849.jpg

piston 2 - pic taken from driver side - back of piston is toward the top of the pic:

IMG_20210321_211855.jpg

piston 3 - pic taken from driver side - back of piston is toward the top of the pic:

IMG_20210321_211900.jpg

piston 4 - pic taken from driver side - back of piston is toward the top of the pic:

IMG_20210321_211907.jpg

piston 5 - pic taken from driver side - back of piston is toward the top of the pic:

IMG_20210321_211915.jpg

piston 6 - pic taken from driver side - back of piston is toward the top of the pic:

IMG_20210321_211923.jpg

A few more pics:

IMG_20210321_211944.jpg  IMG_20210321_211951.jpg  IMG_20210321_211959.jpg

IMG_20210321_212012.jpg  IMG_20210321_212018.jpg

 

I did this with a die grinder and oval cutter.  Tape and bag is still in place.  I think I will switch over to a tapered roll and try to look for inconsistencies to address... as well as smooth the eye brows to final finish.  I am well above the top ring land currently, and inside the fire ring on the head gasket as well.  I was being cautious (I hope!).  I will check clearances and continue - before I bolt the head on.

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Posted (edited)
On 3/22/2021 at 6:20 AM, grannyknot said:

Looks like it was done on a milling machine! 👍  As long as the head gasket didn't go through a heat cycle by starting the engine you should be fine to re-use the HG.

Thanks. I appreciate the positive reinforcement!  I have been studying it and the cylinder head for a few minutes each of the past couple of days.  I want my next steps to be right ones.  

Checking the gasket against work that has been done so far on the head (valves are marked with cylinder number):

IMG_20210323_202517.jpg  IMG_20210323_202532.jpg  IMG_20210323_202545.jpg

IMG_20210323_202556.jpg  IMG_20210323_202603.jpg  IMG_20210323_202652.jpg

The work already done to open up the breathing on the exhaust for #1 and intake for #2 puts the edge of the combustion chamber at the gasket edge, but only for these two edges: 

IMG_20210323_202750.jpg  IMG_20210323_202809.jpg

It seems desirable to do further work on the other sides of each of these chambers to align the chamber edge to the fire ring also... and to do the same for the areas where the chamber wall is close to the valve heads in the other chambers as well.  That said, the tops of the bores are not as wide as the chambers in the matching areas, even after eye-browing.  So, the question is should I open them outwards to match?  And, should this be done for both the intake and exhaust valve sides of the cylinders (safely above the number 1 piston rings of course)? 

 

Edited by inline6
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1 hour ago, inline6 said:

It seems desirable to do further work on the other sides of each of these chambers to align the chamber edge to the fire ring also... and to do the same for the areas where the chamber wall is close to the valve heads in the other chambers as well.  That said, the tops of the bores are not as wide as the chambers in the matching areas, even after eye-browing.  So, the question is should I open them outwards to match?  And, should this be done for both the intake and exhaust valve sides of the cylinders (safely above the number 1 piston rings of course)? 

I'm sorry, but you completely lost me with your description stuff above, but I will throw out some general notes that may be applicable.

First, any material you remove from the chamber area in the head will reduce your compression ratio. You could gain that back in other ways, but not sure you were planning to do any of that. If you like the compression numbers where they are, you might not want to remove any more material than you really need to.

Second, Not sure it matters, but I've measured a couple head gaskets, and I've found that the hole in the gasket is not round. Not sure it was an anomaly (or just a 280 thing), but they were oval-ish. Have you checked yours to see if it's oval or round?

Third, when you're removing material from the head to bring the edge out to the fire ring, keep in mind that the metal band portion of the gasket will squeeze out into the chamber area a little as the gasket is compressed. If it were me, I would want the entire fire ring area to be supported on both sides by engine metal. In other words, I wouldn't want to ever have any portion of the fire ring hanging out unsupported (on either side) into the chamber area, and because of the extrusion that occurs on compression of the gasket,  I would probably leave a small amount of extra material there to be sure that would not happen. I believe the gasket you have there is the one that was already compressed once? That may minimize that effect?

I'm no engine builder expert, but those are my thoughts. Hopefully someone who actually knows what they're talking about comes in and provides better guidance.    LOL

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Thanks for your comments!

8 minutes ago, Captain Obvious said:

I'm sorry, but you completely lost me with your description stuff above...

Yeah, is hard to explain.  Basically, if you look at each of the pics of chambers 1 through 6, and look at the 3 o'clock and 9 o'clock positions specifically for each, only chambers 1 and 2 have edges that match up with the fire rings... and further, for the #1 chamber, it is only the exhaust valve side that matches up (3 o'clock position in the pic), and for the #2 chamber, only the intake valve side matches up (also the 3 o'clock position in the pic).  All of the other combustion chamber edges (at 9 o'clock for all chambers, and at 3 o'clock for chambers 3 through 6) are not yet cut as far as the edge of the fire ring.

So, I am saying it seems like I need to open the chambers at those positions for each chamber so that they all align with the edge of the fire rings in the gasket.  

8 minutes ago, Captain Obvious said:

Any material you remove from the chamber area in the head will reduce your compression ratio. 

Understood.  I have to provide clearance for the valves, so trying to do that, and I am assuming that breathing benefits that come from what I have outlined will be worth more than compression lost from the mods.  I have no idea though - so if there is an expert who chimes in, that will be great!

8 minutes ago, Captain Obvious said:

Have you checked yours to see if it's oval or round?

Yep, it is oval.  It is wider at 3 and 9.  And I'm not touching anything at 6 and 12... or 5 and 11, or 7 and 1 for that matter.  I probably went a bit far north and south with the eye brows I already cut in the block at the 3 and 9 positions.  The rest of my mods to the block will be more central to the 3 and 9 positions, generally.

8 minutes ago, Captain Obvious said:

Third, when you're removing material from the head to bring the edge out to the fire ring, keep in mind that the metal band portion of the gasket will squeeze out into the chamber area a little as the gasket is compressed. If it were me, I would want the entire fire ring area to be supported on both sides by engine metal. In other words, I wouldn't want to ever have any portion of the fire ring hanging out unsupported (on either side) into the chamber area, and because of the extrusion that occurs on compression of the gasket,  I would probably leave a small amount of extra material there to be sure that would not happen. I believe the gasket you have there is the one that was already compressed once? That may minimize that effect?

Agreed.  And yes, the gasket has been compressed once.  But I will leave a small amount of material there so I am not precisely at the fire ring with the edges of the chamber.  The two edges mentioned above that are already matching up are REALLY close.

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CO covered it,  the gains in flow to result in more HP are so small as to be unnoticeable, what you are talking about is the sort tweaking that is done a race engine to squeeze the last bit of potential out of it and you would only benefit from those possible gains at WOT and how much time do you really spend up there?  If I were you I would reassemble with some molding clay or a bit of Plasticine at the 3 and 9 position, just tighten the head bolts down a little snug and cycle the engine by hand a few times to see if you have covered your clearances. If at anytime while rotating the engine by hand you feel the engine stop or resist, back it off and remove the head to figure out where the interference is coming from. The thickness of Plasticine at the bottom of the valve dent will give you a good idea of how close you are.

I understand perfectly the desire to make the engine as perfect as possible while you are in there, it's fun just be aware of the law of diminishing returns.

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Agreed. I guess now that you have moved the chamber edge back on E1 and I2, if I were you, I would do something similar to the rest of the valves, but making sure I didn't push it to the hairy edge and left a little material to guarantee that the head gasket ring didn't squeeze out past the material.

Other than that, the only other thing I would do is make sure I broke the sharp edge where the new head planing surface meets the chamber. And I wouldn't even use power tools... Some fineish (400?) grit sandpaper ought to knock down any burrs and put a small radius on that edge.

In other words... When they plane the head, they usually use a large cutter spinning in one direction. Because of that, it usually results in a burr (most prevalent on the downstream side of the cut). I would take some fine grit paper and work it around the chamber something like this to knock off any smeared burrs and/or make sure there aren't any sharp edges:
cyl1.jpg

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Posted (edited)

Chambers 1 to 6 in order from left to right after very little ground away, only nearest the valve and to the fire ring:

IMG_20210327_171103.jpg  IMG_20210327_171112.jpg  IMG_20210327_171142.jpg

IMG_20210327_171151.jpg  IMG_20210327_171201.jpg  IMG_20210327_171245.jpg

I put the entire head inside a plastic bag and taped off everything so I didn't get any grinding dust anywhere in the head or valves, etc.  

I will check valve to block clearances next.  Before the head goes back on for good, I will address any sharp edges that remain.

Edited by inline6
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Posted (edited)

I am getting close to satisfied with the block eye brow and combustion chamber mods.  I have a few areas I see in the pics that need attention.  I actually can see them better in the pics because I can zoom in on them and compare from one cylinder to another.  So this is helpful to document them in this way.  

Cylinder 1-3 and 4-6:

IMG_20210330_214358.jpg  IMG_20210330_214405.jpg  IMG_20210330_214413.jpg

IMG_20210330_214423.jpg  IMG_20210330_214432.jpg  IMG_20210330_214440.jpg

 

Cyl. 1 exhaust (front of bore - also note ring location by rust stain), Cyl. 2 exhaust (back of bore),  Cyl. 3 exhaust (back of bore):

IMG_20210330_214518.jpg  IMG_20210330_214726.jpg  IMG_20210330_214737.jpg

 

Cyl. 4 exhaust (front of bore), Cyl. 5 exhaust (front of bore),  Cyl. 6 exhaust (back of bore:

IMG_20210330_214600.jpg  IMG_20210330_214617.jpg  IMG_20210330_214822.jpg

 

Cyl. 1 intake (back of bore - also note ring location by rust stain), Cyl. 2 intake (front of bore),  Cyl. 3 intake (front of bore):

IMG_20210330_214713.jpg  IMG_20210330_214534.jpg  IMG_20210330_214549.jpg

 

Cyl. 4 intake (back of bore), Cyl. 5 intake (back of bore),  Cyl. 6 intake (front of bore):

IMG_20210330_214747.jpg  IMG_20210330_214805.jpg  IMG_20210330_214638.jpg

 

I think I have those all labeled correctly.  Of course, I also still need to assemble everything in mock fashion to check clearances. 

 

Edited by inline6
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Posted (edited)

I added clay to replace the material that was removed from the bores for eye-browing the block.  I then put the head gasket on, lightly bolted the head on, and ran the engine through revolutions to check for valve interference.  When I took the head off, there was none that I could perceive - there were no marks in the clay.  Of course, this engine is bored over a bit, so there was that chance before mocking it all up that they would not hit.  🙂

After checking that, I pulled all of the clay off and combined it into one piece which measured out to less than 1 cubic centimeter.  So, compression ratio is not significantly reduced.

Some pics - Cylinders 1-6 in order:

IMG_20210404_132657.jpg  IMG_20210404_132703.jpg  IMG_20210404_132705.jpg

IMG_20210404_132712.jpg  IMG_20210404_132715.jpg  IMG_20210404_132719.jpg

Additionally, my fuel line assembly was pretty bent up, so I put it on the engine in a mock up fashion and worked on straightening it for an hour or more with a crow bar, vice grips (with wood stirring sticks used for protection from marks), and a hammer.  It looks ok now, but I wonder about the brackets, if they are near original in appearance, or if they are quite bent still.  The parallel aspect of the two lines seems pretty good to me.  The brackets dictate the height of the lines along their lengths without much variance.  

IMG_20210404_181452.jpg  IMG_20210404_181517.jpg  IMG_20210404_181527.jpg

IMG_20210404_181538.jpg  IMG_20210404_181636.jpg  IMG_20210404_181724.jpg

IMG_20210404_181730.jpg  IMG_20210404_181738.jpg  IMG_20210404_181750.jpg 

 

I want to be sure the shape of the lines in the assembly is all sorted out before I send it off for re-plating.

Edited by inline6
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On 4/7/2021 at 9:40 AM, jfa.series1 said:

Here's a pic of a similar one I restored for comparison, our OP is right on target.

Thanks for that.  I see differences in the brackets.  I will work on mine more and make it look like that one.

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  • 1 month later...
Posted (edited)

I see it has been a long time since I posted an update.  I am still working on fasteners.  I suspect that I am putting too much time into them, but I have no experience with getting hardware replated.  So, I feel I can't leave it up to chance.  I will probably send some "test" hardware along with it in various stages of prep or lack thereof.  It will be interesting to see how the test hardware compares to my fully prepped hardware.  

I have a few observations to share, but not much of an update.  First, the u bolt that holds the steering rack from twisting on the front crossmember - I happen to have two.  There is a white blot of paint from the factory.  I noted that under the white blot, the part was silver.  So, this part seems to have received zinc plating (clear) from the factory. 

IMG_20210411_203715.jpg 

The clips that secure a rubber weather strip to the unibody under the top of the fender, here in their as removed condition.  Amazing that they don't even have rust on their entire surface: 

IMG_20210515_130814.jpg  IMG_20210515_130844.jpg

 

The battery inspection panels have these metal clips.  I find it interesting that they received a black coating originally that is not paint.  This is actually consistent with other black plated parts I have found on the car.  Black parts are, nearly without exception, springs or springy.

IMG_20210515_140706.jpg  IMG_20210515_141317.jpg  IMG_20210515_140723.jpg

 

The bushing in the bracket that bolts to the engine compartment firewall, which supports the back of the main throttle rod, is always rotten on any 240z.  It is a two piece bushing, with a plastic inner barrel and a rubber outer grommet.  The rubber part broke when I pried it out of the bracket.  Here it is temporarily put back together:

IMG_20210520_202632.jpg

First pic has half of grommet removed.  Middle pic is of the plastic barrel by itself.  I will be trying to source a similar bushing from McMaster Carr.  

IMG_20210520_202650.jpg  IMG_20210520_202904.jpg  IMG_20210520_202942.jpg

 

And lastly for today, I find it interesting that the hatch hinges were bolted into the car when it was painted at the factory.  The odd part about that is that the rubber enclosure was in place also.  My car had shims on the right side hinge only, and you can see by the original paint that they were in place when the car was painted.  This, and the fact that the taper head bolts that hold the hatch to the hinges were not originally painted, tells me that the hinges and hatch were bolted to the car for fitment, and then the hatch was removed (the four taper head screws only were removed) for the original paint application at the factory.

IMG_20210523_140205.jpg  IMG_20210523_140214.jpg  IMG_20210523_140649.jpg

 

Also, hinge assemblies and shims were clear zinc, and backing plates were yellow chromate/cad.

IMG_20210523_140422.jpg  IMG_20210523_140411.jpg  IMG_20210523_140252.jpg

 

I think I am nearing the end of the great fastener round up and restoration of 2020/2021.  I ordered some new ones a couple of days ago to fill in for the small number of originals that went missing at some point.  I am digging through my boxes of old Datsun hardware to find suitable replacements also.  I am having some success there, finding matching hardware with 4's and 7's and 9's on the heads of bolts - proper style and length.  Yeah... I am more than a bit OCD I think.

 

Edited by inline6
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That is serious attention to detail,  and not the least excessively so.

One of the biggest problems with restoring anything is finding detailed information such as that you've provided. 

Good onya lad, I say.

Now, we just need a database of all this good info.  Anyone need a full-time job?

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1 hour ago, inline6 said:

I have been working on documenting the fasteners on the car.  When I finish all of the documentation of the hardware, I will upload a worksheet to the resources section.  In the meantime, anyone with a google account can access what I have so far by going to the link:

Wow, nice list!  Very thorough..

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