Sam and Nate get started with prepping this old short block engine for a top end rebuild.


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Watch Sam and Nate get to work prepping this short block engine for a top end rebuild.

Sam and Nate begin the process of putting a new top end (pistons, cylinders and heads) on their old short block which seems to have some life left in it still. As this is Nathan's first top end, Sam takes the extra time to go though all of the steps in checking and setting the piston ring gap, "CC"-ing the combustion chambers and the checking the deck height so they know what the compression ratio of the engine will be.

Video Transcript

Hi guys, I'm Sam. I'm Nate. And we're going to start doing some preliminary work so that Nathan can build his first top end and do it by the book, so to speak. We've got some guidelines. We take a little bit of what Volkswagen does, a little bit of modern piston technology, and what we know about combustion science or anything like that, setting piston rings, especially as far as the ring gaps and whatnot. There's a whole lot of different philosophies. A lot of that changes based on what style of piston ring you've got. Regardless, we're going to do some checking with these pistons right here. We're going to go through and set our ring gaps, or at least check our ring gaps. We've got an old piston, very handy to actually have a piston with the top ring in place because that just so happens to set our depth for when we check our piston ring. That's pretty handy there. Another thing is, like I said, different styles of piston rings. Original style piston rings, the oil ring was a pseudo one-piece unit. You had this maybe graphite scraper here with an internal spring. So when you're setting ring gaps, you only have three spaces to actually check your gap on or to line up anyway. And Volkswagen did those gaps at 90°, 90° basically lining up with the wrist pin, and the oil gap at the top. We're going to change that up a little bit, but we'll get into that later. Like I said, if you have the ring in place, you can just draw this in top of the cylinder, and that will set our rings in place, and then we can go through and check the gap.

So hopefully, should go pretty smooth.

Right, hands are clean?

Looks clean.

And just for ease of packaging, as I imagine why all piston manufacturers install the piston rings and ship them in place, it keeps the pistons in place in the cylinders, keeps them from scraping around, and makes certain that the rings don't get broken in packaging. I can tell you this, when I built my first engine because I didn't have access to a ring compressor, I did the old trick of just push the cylinder out just far enough

so you could put the wrist pin in?

So I could put the wrist pin in and then I pushed it right back in place. You have no idea what those piston rings are set at, and we'll find out here in a moment. So, Nathan, if you want to do the honors.

Push it all the way out?

Pop it all the way out.

Oh yeah, it looks way different already, huh?

So you can see that these gaps are already lined up. Our scraper ring, not 20° off of that, and that one's right lined up with it. So chances are this engine would have had a lot of blowby. Those rings weren't even really 90° apart, and the way they were lined up, not ideal for a proper running engine.

So, that is why we put them the right way.

That's why we put them the right way.

Which is this chart right here?

Yep, but first things first, we're going to pull these off. We're going to install them one at a time inside of our cylinder, and we're going to check our ring gap. Now, a couple of things. Do this one cylinder at a time. We're going to take those away, and we are going to get a marker out. We're going to just write on the journal number one. We'll write on here someplace, ideally that's not going to get marked off, number one because all these rings that are with this piston, we want to keep them with this piston cylinder, cylinder.

There's a whole ton of junk and stuff in there.

Yep, and that's another reason why. What do we got there as far as numbers?

85.6, it was 85.7 a second ago.

Now if we were to put it on the bottom.

85.6 for a second there, 85.5.

What I'm trying to illustrate, and I think it's probably doing a good job, is these are typically slightly smaller at the bottom than they are at the top. Now, we don't want to check our ring gap at the top. We want to check our ring gap at the bottom where the cylinder is smallest. So as this cylinder slides down, that gap will tighten up. So if we were to set a very tight gap at the top where this cylinder is larger,

it's not going to be very, or it's going to be too tight at the right?

Correct, because that cylinder as it goes down is going to get smaller. So we're going to set our ring gaps at the bottom. For the first time in my life, since I figured if I'm going to show my son how to do it, I might as well show my son how to do it right. I got a pair of piston ring pliers. I know, novel concept. You're going to get in there in between these two slots, and you're going to push this together and pull it out. Do that for all those up down until all of them come out.

So like that, and off like that, right? Is there a specific order that they need to be in, like top to bottom?

You mentioned, look at the side profile of that. Is it square? Is it tapered?

It's a bit of an got an angle right there.

Okay, pull the next one off.

It's more squared.

And there's yet another reason why you want to pull out your rings. Now, these are oil rings.

And do did they come off the same way?

Same way, these are a little bit smaller and easier to get out because they're more flexible. So just like that, and I'll let you do this next one.

Would you just go right where the green and the red mark is?

No, you look for the gap.

Oh, there's a gap.

And you can try it with the pliers, but I don't know if it's going to work. Try it.

Um, no, don't think so. Let's see, can we push that back?

No, hold onto the rings with your hand with one hand, and then with the other hand, pull it out carefully, make certain that you don't scratch the cylinder. I'll do it again, like that. Now you can pull off the scraper.

Which is that right? Oh yeah, it's pretty easy, huh?

Green, red, butt up there you go.

And boom. Wow, that's easy.

It's not perfectly clean, but it's clean enough, especially we rinse all this stuff out. Said, now that gives us a nice way to push our new rings in place squarely. Going to set that to the side, take our ring, and again, we want to make certain that we're paying attention to what side is top and which way that goes. Get that's set, that is a very snug ring. I can already see, yeah, push that down.

Yeah, there's like a tiny bit of a gap. You might be able to,

That is our gap, and for our top ring, we want it to be 15,000 of an inch. So I've actually got our feeler gauge over here. We've got our 10,000 for our oil ring, 13,000 for our second compression ring, 15,000 for our top compression ring.

Which this is our top compression ring, right?

This is our top compression ring, so we're going to take this and see if we can fit this in there. I don't think we can.

Which is what the grinder is for, right?

That's what our grinder is for. We cannot fit that in there. We're going to take this out, so this is just a no-name brand ring grinder I got off of Amazon.

And then just start cranking?

Just do a little bit. Yep, you can always take more off, you can't put more on.

And you can see here that we took off just ever so slightly, hardly nothing, but that's fine. We want to start with less. We going to always take more off. We can't put more back on, and boom. And can we fit a 15,000 in there yet? No.

Not quite, just a bit more, huh?

Just a bit more.

Hey, look at that, we got a square grind mark across our entire ring. Push it in, boom, and well, we can see daylight between the two now, but we still, oh look at that. We are just out there now. That is a very, very snug fit.

I mean, I'd say just do a tiny bit more, maybe.

Yes, also we want to be concerned with how our gap looks in there, and actually,

Yeah, it looks pretty square.

That's exactly what I was looking, referring to. Our gap looks square. Take our feeler gauge, it is in. You know what, buddy? What? I'm gonna call this one good.

It's pretty good, huh?

That one's good. Um, pay attention, though, hold on. Was this the, I believe, should be the top ring, squared across the bottom, usually the one.

That's a middle ring though, right?

Is this the middle ring or the top ring?

The top ring was the one with the little edge on it.

Uh, this is our top ring.

No, that is our middle ring because it has a little bevel in it. Okay, this is our top ring.

Top ring has the bevel towards the inside. Yeah, the middle ring has step on the bottom. So we just set our bottom ring

to 15, but that’s fine cuz the max is 0.035.

35,000 would be our max. We've got this one. We'll check it for 13 thou. It's probably, obviously a 15 thou fits. 13 will because it's less,

but let's see if it's a bit smoother.

Yeah, 15 is a tight fit.

Yeah, so hopefully it should be good on the 13, huh?

Yeah, it's still 13 is a

kind of snug.

It's a snug fit.

That's good.

So our middle ring, our gap is set on it. Top ring,

which should be in the bevel

should be up says on the ring.

Boom, and now just press down, so 015.

15,000. It's good to go?

That's that feels here, feel it. That feels pretty darn good.

All right, so that one set, yeah.

Boom. That was easy. So now the bottom rings, or the oil rings, which are these things, which that thing shouldn't be set, huh?


That's just there. Those guys should be. Let's check, good to go. That's good.

All right, pop that one.

Smells, feels smooth but not like super shaky.


Like just where we want it, huh? Let's see, that's good, good to go. It was just that one that we needed to set apparently, which that was cool, huh? All right, and boom. That's one set.

You know what to do, so I'm going to sit back one, put all your rings in there Once we set the deck height, we're going to have to use a couple of cylinders, and we're going to set these up. This is going to be cylinder number one. Next one's going to be cylinder number two, etc., etc., etc.

This one should be cylinder number two because it's a one cuz this one's right together, and this one, so now just press it out.

We set this guy aside.

And do number two.

Is that still not enough? No, it doesn't say. It's just sign around. Boom, and a how, throw that back in the trash. I'm guessing we don't need any of this stuff now.

Not for this step. All right, we're back from dinner. Hopefully, I don't have anything in my beard this time. You didn't let me know I had the piece of my beard last time. Probably kind of silly. All right, we've got some water that we've tinted blue with a marker and, oh, and Happy Valentine's Day everybody. It's Valentine's Day, and here we are in the garage. No, we do have spark plugs in all four of our chambers. Are these ones threaded in as much as those ones are? No, they're not. Let's do that. All right, we'll wipe those, you wipe those combustion chambers down on that side.

You might as well do on all four, though.

So you guys have seen me do this many times, or maybe you haven't. If this is, if you guys are new to for watching jbugs videos, now that we've got our blog series, they're a little bit more for entertainment and fun, but you're still going to learn something on occasion.

Yeah, potentially, and sometimes I learn stuff.

Oh, this is for teaching you someday doing this stuff without me, like working on cars. You say you do, yeah, and you're have to do this without me one day, ain’t gonna be here forever.

Make certain this thing stays level. Level, yeah, there we go.

Level enough.

So we've got a syringe. We've got a little clear plastic cup. This will sit over the top of our combustion chamber, and we're going to take note of how much water goes in this cup. A little bit more than 60 mls at this point, 60 mls?

Yeah, about that.

And now we're just going to inject the fluid, huh, injection molding.

So what does the blue water do exactly?

It fills up the combustion chamber. There we go. All right, now we're getting up to that point where, well, these got some big chambers. That's almost, well, never mind, that is 60 ccs.

Oh yeah, so that's how it works, huh?

We can't get some of that air level out. There we go, a little, little bit of tension right there, get a little bit more water so that's 60 ccs, we'll fill up on that, see if we can get some of this water, this air to escape.

Oh yeah, huh, think might need just a tiny bit more water.

Got some big combustion chambers on these guys.

Yeah, huh, is that necessarily a good thing, or?

It's going to be a safe thing. It's not going to have tons of power, but got one of them, come on, there we go, got that off the edge.

Yeah, there we go, right, definitely going to need a tiny bit more, huh, and boom, there we go.

All right, what do we have left, 15, 16 ccs? So we put in 64 ccs of liquid, that's how much volume is in that chamber. Now we're going to do the same thing over here.

All right, so how much do we have left?

16, 17, yeah, 17.

Yeah, 20 to start with, so one ml, I mean we actually got a little bit gap still in there. Go ahead and try to put one more ml, that's a little bit more than at 1 ml, but yeah, pull it out just a touch, yeah, 16. All right, so these are both the same size, let's check one of these guys over here.

Did you take note of how much you put in there?

About one.

We're going to call that one two cc combined.

Yeah, was close enough.

Grab that cup. Make sure that all of our, that just make sure that all the keepers and seats and everything else on our springs for our valves is all set.

And boom, now throw it together.

Now we can go check our deck out. Everything that we do, if we only do one piston, we're going to set number three. Number three typically runs the hottest because it's farthest away from the center line of the fan, and that's why Volkswagen went to the doghouse oil cooler, etc., etc., yada yada yada, blah blah blah. But anyway, everything we do, if we only do one cylinder, we work on number three. So watch your eyes 'cause you always have a way of getting your eyes in the way of the brake clean.

So what exactly are we doing?

We are going to check our deck height, that is how much, or how far up in the cylinder the piston travels that at top dead center.

Does that mean that we put the wrist pin in?

We put the piston in the cylinder, in the wrist pin, etc., etc., etc., etc.

Which means the rings too, right?

Nope, we don't use the rings, cylinder number three, we're doing everything at cylinder number three, so we're going to use cylinder three, piston three, we're going to set that, get that started in there. Now note, we want to make sure that that arrow indicates towards the flywheel, start the wrist pin first,

Boom, there we go, square, it's super actually smooth.

Make sure that you line up with the rod, we are all right, square there, you go, everything there. Oh, this is not going to be a high compression engine, good grief, am I not all the way down? Look, I don't think we are all the way down, are we? No, there we go, I was going to say, that was nowhere near all the way down.

yeah, I was going to say, um, that's going to have a whole maybe

five horsepower


These, we're just going to snug everything up.

Yeah, because that's not going to permanently stay on there, of course.

Got to make sure the cylinder is seated against the case, snug, snug. So according to the crankshaft, that is top dead center, and I was to go through, move it, agree this way, did look good, yeah, agree that way, yeah, I would agree, so that is top dead center. Now we're going to put some fuek gauge in there and see how much room do we have in there, and actually, all right, we can, I can't get a fingernail in there, but 49 plus 23 is what?

Uh, 49, 59, 69, nice, and then three, 70, 71, 72. Yep, huh, that's cool.

Well, we don't have 72,000 of deck height, go with 11, we have 11 in here, I put 11.

We only need to do this on one, right?

Do them on this one, and we're going to check the other side as well.

In number, that's number one, right?

Which is 60,000, might be that, might be about it. I can probably do a little bit more, let's see, that was 11 and 49, that would have been 60, like 65, so let's go, 16,000. Center, center, still fit, so we got 65,000. 64cc combustion chamber over here, that down, so 34, number three, we've got 65,000 deck height, got 64cc, let me take those numbers,

Calculate on the Samsung tablet.

We're to calculate on, jbugs compression calculator, boom, boom, boom, cylinder bore, 85.5, oh, oh yeah, can't get away from our marketing department, broke stock 69, nice. Uh, we are going deck height in inches, 0.65, combustion chambers are 64, solve for, oh wow, that's pretty low, 6.4 to one compression ratio, so this is going to be a very low compression.

So we will take this rig off, put this cylinder away, grab our other cylinder for number one, and we'll do the same stuff on the opposite side of the engine.

That should be top center, that is, feels snug, feels about right.

65,000 both sides, so a decent set of quality as far as those go. So at this point,

All we really need to do is just assemble it, huh.

Mr. Speedy over here just wants to put this thing together right now, but we still have to clean every single piston, every single cylinder, all the rings, the wrist pins, the clips, the case needs a wipe down, obviously, but yeah, tomorrow, maybe we can start on the assembly. We've got all that to do, plus we have clean up on the heads to do, um, maybe we can do a little bit of that tonight.

Yeah, 'cause we just put water on them.

Clean up for our cooling cages, actually, never mind, these cages are really, really nice, these are some good castings. They might be low compression, but I'll be dog on it if they don't have some nice looking castings. So we can look through there, see Nathan, through all those passages, all those passages through all those fins and those cylinder heads, I mean, these castings are super, super clean, uh, even through here, a lot of times you'll see, oftentimes where these things misaligned and there's a whole bunch of flashing in between them, it's actually really clean, there's a little bit right here actually, so I'm going to clean that up, yeah, I don't know if you guys can catch that on the camera, hold on, one, two, three, four, one, two, four, five, these five bottom grooves, there's a little bit of flashing that goes up to the edge, I'm going to clean that up, but otherwise, these things look really, really good, even down the centers here where the thermostat rods would go, they look clean, there's a little bit of flash. Take a little flush tool down the line, side looks good around, this just like that, up, white, let's try not to drop this thing.

A bit of dust.

It's dust and like molding flash, it's just in between the castings, or you just got a little bit of flash, this is all the material we're taking out, hardly nothing at all. All right, Nathan, you got to do the next one.

Way better, all of them, yeah, nice. We've got everything set up, ready to go, we've got our piston ring gap set, we've got our head cc’d, we know what our deck height is, opposite sides of the case, we're going to trust that Volkswagen made these things the same, seeing as we had the same deck height on one side as we did on the other. I'm going to trust that all four of those are the same, at least on the castings, uh, but either way, we're not dealing with a high compression motor, 6.2, 6.4, 6.7, somewhere in that neighborhood, but along those lines, uh, we'll get things cleaned up on the case and all of our parts, and we're going to start assembling this tomorrow. He's going to start assembling this tomorrow, 'cause this is his motor, his build.

With some supervision, of course.

With some adult supervision. I'm not going to say professional supervision, 'cause I'm not a professional engine builder, um.

Me neither definitely.

Not yet, anyway. But on that note, we're going to call it a night. Life's full of good people.

If you can’t find one,

be one.

Late guys.

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