file this under "C.S."

Older engines, especially larger older engines, are sometimes referred to as, "fix-it-with-a-hammer simple," or "fix-it-with-a-file simple," or various variations on this theme.  The idea is that they were made to be so robust, and with such loose tolerances, that no particular precision is required when working on them.  It is often said with admiration and nostalgia for the "good old days," but can also be used with snide derision.  The latter typically comes from someone who is either trying to sell you a newer engine, or someone who has just purchased a newer engine.

 

I would not classify my 1972 LS3 as either "fix-it-with-a-hammer," or "fix-it-with-a-file," but that doesn't mean that nothing ever gets hammered or filed in the process of working on it.

 

One thing that required filing was the piston rings.  Piston ring end gap is the size of the gap between the ends of the piston ring when it is installed in the cylinder bore.  On a stock engine, this is set per the manufacturer's specifications, and when stock piston rings are ordered, they almost always come with the correct end gap.  Performance engine builders, however, may want to set their piston ring end gap at some size other than what the manufacturer recommends.  For that reason, aftermarket piston rings can be purchased with zero end gap, and then filed to give whatever end gap specification the engine builder wishes to use.

 

I accidentally ordered piston rings that were not gapped, and would require filing.  Here is a picture showing that the ends of the piston ring butt up to each other in the cylinder bore.

 

 

The ring is actually made to have a negative gap, i.e., the ends want to overlap each other.  You would never want to assemble an engine that way, but I guess it allows the engine builder set any gap he wants to.  I suppose it might even also allow the engine builder to run the ring in a larger cylinder bore, if he wanted to reduce ring tension or something like that.

 

So, I accidentally ordered these rings, and then I found out that since I'm not using stock pistons, the piston manufacturer recommends a different end gap than the stock specification, anyway.  Their piston runs the top ring closer to the piston crown than a stock piston, so the ring tends to get hotter, which means it will expand more, which means it has to have a larger end gap or else the ends will butt up against each other and start to buckle the ring.

So, I ordered a ring end gap filing tool online.  There are much nicer versions of this tool, which are also much more expensive, but I figured I could get by with a little hand-cranked version.  I unbolted the bench vise and swivelled it out of the way, and used one of its bolt holes in the bench to hold the end gap filer down:

Coincidentally, I mentioned this project to a guy I work with, who used to work for Ford in their NASCAR program.  He said that Ford told the NASCAR engine builders to just let them (Ford) know what size ring end gaps they (the engine builders) wanted, and Ford would supply the rings.  He said that Ford just didn't think the race teams were careful enough when they filed their rings, and so Ford preferred for them not to do it.  So ... that was a little daunting, considering that professional engine builders supposedly can't do this job reliably, but I decided to just take it as good advice to be extra careful.  Anyway, I'd already ordered the end gap filer.

Here is a photo of a ring on the end gap filer, ready for filing:

The tool is very simple in concept, but the key feature is the two little pins sticking up on either side of the grinding wheel. In theory, you could use a hand file to file piston ring end gaps, but the danger there is that you have to be really careful to make sure that the ring ends stay parallel to each other (and perpendicular to the cylinder wall). I didn't trust myself to do that sixteen times (two rings per cylinder), so I bought the end gap filer. The vertical pins are positioned so that when you place a ring on the filer and push it up against the pins, it will keep the end that you are filing parallel to the grinding wheel, which will ensure that it will be parallel to the other ring end when you are done.

They say that you should always turn the hand crank towards yourself as you are filing.  I assume this is so that any burrs that don't get removed will be pointing away from the cylinder wall when the ring is installed.

So, you put a ring on the filer, turn the crank some, file a little material off, and then you have to check your progress.  To check the end gap, you install the ring in a cylinder and then measure the gap with a set of feeler gauges.  To install the ring, you just put it in the cylinder, and then use a piston to push it down into the bore.  The purpose of using the piston (upside down, with its crown touching the ring) is to keep the ring square in the bore.  If the ring isn't square, you won't get a good measurement.

I read some texts that said you should measure the end gap at the bottom of the piston's travel, and others that said you should measure it at the top of the piston's travel, but either way, they're basically saying to measure it close to where ring reversal will occur.  I did it at the top, because that way you can use the ring grooves on the piston to see where ring reversal will be.  In other words, if you have the piston upside down with its crown on the ring, and the corresponding ring groove is at the deck of the cylinder block, then that should put the ring in the area where ring reversal will occur.

(Regarding the photo above:  sometimes when you don't know what you're doing, you might wear a shirt that makes it look like you do.  Sometimes that shirt might have a nametag on it.  Sometimes that name might not be yours.  Sometimes that name might be "Kaiser.")

After the ring is in the bore, you can remove the piston and measure the end gap using a set of feeler gauges.  This photo shows a properly (I hope) gapped top ring in the bore:

For the ring set that I got, the top rings are a much harder material than the second rings.  I had to file a ring for more than five minutes continuously to even start to get close to the proper end gap.  When I did the second rings, I actually took off too much material from several of them because I didn't realize that they were a much softer material, and even after I knew that they were, I had trouble adjusting to how much easier it was to file them.  I ordered some more second rings to start over and get it right.

After the rings were filed, that meant I could finally start assembling the engine's bottom end.  First, I built up eight rod-and-piston assemblies, and installed the rings on the pistons.  The piston manufacturer said to use an engine assembly lube on the piston wrist pins, but not grease.  The engine assembly lube I'd been planning to use was Lubriplate, but the Lubriplate tube said "grease" on it, so I decided not to use it on the wrist pins.  Instead I used a Lucas Oil engine assembly lube, which is a green oil that is thicker and stickier than engine oil.  I figured it seemed like it fit the bill for what the piston manufacturer wanted, and it also has a nice minty smell to it (no, really!).  After building up the rod-and-piston assemblies, I was finally ready to start putting pistons in the block.

When I worked in my first job after college, I got to go to Switzerland to get trained in how to work on a 20L V8 diesel that our company made.  Their process for lubricating the piston and rings before installing them in the engine was just to dunk the whole piston in a tub of oil.  I thought that seemed like a smart and effective method, so I cut the top off of an empty five-quart oil jug, and poured in one quart of my camshaft break-in oil.  That gave me a convenient source of break-in oil for dunking pistons, as well as for lubricating cylinder walls, and anything else that needed oil.

It's messy, but it's effective.  I put a large zip-lock bag over it to keep it clean when I'm not using it.

So, one at a time, I dunked a piston, put it in the piston ring compressor, lowered the dangling connecting rod down into the appropriate cylinder, and tapped the piston down into the cylinder.

Then I seated the rod on its journal on the crankshaft, and torqued the rod cap.

Eight happily torqued rod caps:

A left bank's worth of happy pistons:

And if you can't tell that those pistons are happy ... well, I just can't help you with that.

forest update

So what's actually going on here?  I always get distracted looking at trees, and lose track of the forest.

Body work has been steadily progressing, probably because it's the one thing that I'm not responsible for.  Every time I see the guy at the body shop, he shakes his head slowly with a wide-eyed look and says, "I never would have guessed it was that bad under there."  Maybe it's an elaborate ruse, but I believe him.  I don't tell him that I'm not at all surprised, just because it seems like this is the way my life tends to go.

They ended up ordering a lot of brand-new, reproduction sheet metal for the car, including quarter panels, the filler panel between the rear window and the trunk lid, a new radiator core support, and new door skins.  There are other parts they would have liked to order, but they aren't available, like the trunk lid, the C-pillars, and probably just a complete 1965 Impala, really.  For those items, they just had to rebuild what was there using sheet metal.

Here's a picture of Matilda with the passenger side quarter panel cut off:

And here's a close-up of the C-pillar on that side, where you can see the remains of someone else's efforts to pull out a dent at some time in the past:

There was a small depression in the chrome trim on the drip rail, like someone had pressed their thumb into a piece of clay.  It fell right in line with that row of holes where someone was pulling out a dent, but I never would have guessed that all that was under there.  Can I pick 'em, or what?

Here's a photo of the driver side, after they put the new quarters on, and with the new filler panel between the back window and the trunk lid:

Notice, also, that they transferred the threaded holes for the blowout straps over from the old filler panel to the new one. They've been very kind about not laughing at me and telling me what a stupid idea that is.

And here is a photo after they had primered the car:

 

It's not a very good picture, I guess I didn't hold the camera steady, or maybe the lens was smudged, or maybe it's just that the full glory of the restored body can't be accurately captured by today's meager technology, it's hard to say.

 

The yellow masking is on there because they were getting ready to shoot the underside of the car with "Lizard Skin."  It's an undercoating that the bodyshop guy swears by. He said it's water-based, but once it cures you need a grinder to take it off. So it gives excellent protection from gravel and moisture and other stuff that wants to ruin the underside of your car.  It is ceramic-based, and it supposedly also helps with insulation from noise and heat.

 

Meanwhile, several weeks ago they got the frame stripped down, blasted and powdercoated, and delivered it to my garage.  I've got it sitting there on jackstands, awaiting installation of the suspension and drivetrain:

It is somewhat maddening to look at it sitting there, knowing that I have 90% of the parts I need to put it together, but unable to start without those last 10%.  I've got the front control arms bolted up now, but I need to get my rearend rebuilt before I can really put the rear suspension together.  There are a few other loose ends on the front suspension, too.  At the same time, I am making slow progress on engine assembly, so I will mount the engine and transmission before the frame goes back to the bodyshop.  I will also run some fuel and brake lines.

To try to organize my thoughts on what all needs to be done, I created a little work flowchart, and I try to get a little bit done every night:

It's similar to a lot of other common project management tools, but I think I kind of invented this exact format when I was working on a project at my old job.  One thing I like about this format is that it shows, at a glance, all the things that I could be working on, so if I don't feel like doing one thing at the moment, I can see what other items I could be working in parallel.

Also, as I go along, I typically remove items that are completed to make room to break out the next tasks into smaller, more detailed tasks.  That helps me remember all the little things that need to be done, and gives the satisfaction of crossing things off as "finished."

Anyway, it helps me to anticipate parts that I'm going to need in the future, but it also helps me to focus on doing what needs to be done next, instead of getting side-tracked on things that I don't need right now.  Like painting rocker covers, for example....