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Practical Engine Building: Step 3: Engine Machining

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Step 3: Engine Machining


00:00 - At this point we're just about ready to send all of our components off to our engine machinist however before we do this, there are a few final checks that we want to make.
00:10 Here what we want to do is check our components and make sure that the components we are dealing with are within the tolerance or correct size.
00:18 This includes our crankshaft, it includes our pistons and we're also going to be measuring our bearing clearances to makes sure these are where we want them to be.
00:28 Now in our case with our LS1, we're a little bit limited because we are fitting an ARP aftermarket main stud kit.
00:37 Being that the LS1 uses an aluminium block, we're expecting that the main bearing tunnel is going to distort when these ARP fasteners are fitted.
00:47 This is because they just provide more clamping force than the stock bolts.
00:52 What this can mean is that our main bearing journal will distort and our clearances won't be correct if we measure them here in our workshop.
01:00 One of the steps we're going to require from our engine machinist is a line hone on the main bearing tunnel to get that tunnel back on size and make sure that it is perfectly true with our ARP fasteners fitted.
01:13 For this instance we're not going to be able to check and measure our main bearing clearance but we will be able to measure our big end bearing clearance with our new K1 Technologies rods.
01:25 So we're going to start here with our K1 Technologies stroker crankshaft and what we're going to do is go through and measure all of our big end and all of our main bearing journals with our micrometer.
01:35 What we're checking for here is just to make sure that they are within the factory size tolerance.
01:43 Let's start with our micrometer by measuring our centre main bearing journal diameter.
01:48 To start with, what we're going to do is take some brake clean and a clean rag and we're just going to give that journal a quick clean.
01:54 What we want to do is make sure that there's no oil present on that journal and make sure that there is no dirt or debris that can affect our reading.
02:03 So we're just using some brake clean here and that's just going to remove all of that material and we're just going to make sure that the surface looks clean so we can get started with our micrometer.
02:14 Once our journal is completely clean, we can take our micrometer and we can measure our journal diameter.
02:20 In this case we've checked our factory specifications and we know that this journal should measure between 2.558 inches and 2.559 inches.
02:30 This is the tolerance for the high and low side of that journal.
02:34 So we're using our two to three inch micrometer and what we're going to do is just place this mIcrometer down over that journal and we're going to tighten it up gently.
02:44 Now when we are measuring our journal diameters, what we also want to do is make sure that we measure in multiple points.
02:50 In particular we want to measure perpendicular to our first reading and we want to measure at both sides of our journal.
02:58 And this allows us to make sure that there is no taper present on the journal and by measuring in two planes perpendicular to each other, this allows us to check the journal for out of round.
03:09 Of course when we are measuring the journal, we also want to be careful of the oil holes and the chamfer of those holes.
03:15 If we get our micrometer located on one of these, this is going to affect our results.
03:19 So at this point we've got our micrometer reading, we've locked our micrometer off before we've removed it from the journal and we can check our reading.
03:27 In this case, our journal has measured at 2.5585 inch.
03:32 So this is exactly between our high and our low limit for our specification.
03:37 Of course now we would follow through and check all of the other main journals in exactly the same way to ensure that all of the journals are on size and that we're comfortable with the journal diameter.
03:48 We'll move on now and we can repeat that process for our big end journal.
03:52 Checking our connecting rod journals is exactly the same, we're going to again start with our rag and our brake clean and we're going to remove any contaminants, any oil, lubricant or debris from that journal surface.
04:11 Once our journal surface is clean we're ready to start taking measurements.
04:15 And again we're going to use our micrometer, the same micrometer, our two to three inch micrometer.
04:22 In this case, the specification from our factory manual, the journal diameter should be between 2.0991 inch and 2.0999 inch, so that's our lower and upper limits.
04:35 Let's take a measurement now.
04:53 When we are using our micrometer here, we want to rock the micrometer gently backwards and forwards while we are tightening it down just to be very very certain that we have found the widest point for our journal.
05:05 Once we've got that point, we can lock our micrometer down and remove it and take a reading.
05:10 Again, with our journals we're going to do exactly the same thing, we're going to be taking multiple readings across the width of the journal to check the journal for taper and again we're checking in two planes perpendicular to each other to check the journal for out of round.
05:24 Now in this case, we've taken our reading and we've found that our journal diameter measures 2.0995 of an inch so again we're just about bang in the middle between our specification limits, our upper and our lower limit.
05:39 So at this point I'm comfortable with that journal, of course again we would continue and check all of the other connecting rod or big end journals of our crankshaft to be sure that they are all within our specification.
05:51 At this point with our crankshaft checked, we're comfortable with all of our clearances, all of our specifications, we're going to move on and the next thing we're going to check is our connecting rod oil clearance.
06:02 What we've done is we've started by taking one of our connecting rods here, one of our K1 Technologies connecting rods and I have torqued the rod bolts up to specification, we've got our King bearings already fitted in the big end journal of that connecting rod.
06:18 So what we're going to do now is we're going to take our micrometer that we've just used for measuring our big end journal diameter and we're going to use this to zero our bore gauge.
06:31 The process with zeroing our dial bore gauge is to insert the dial bore gauge into our micrometer and we want to adjust the dial gauge until the dial gauge is reading zero when we're at the tightest point.
06:43 And this can be a little bit fiddly, what we're going to do here is just rock the dial gauge back and forth through the two anvils in our micrometer.
06:50 So what we're looking for here is the smallest reading on our dial gauge as we rock backwards and forwards between the two anvils with our bore gauge and we can see that that is coming right down onto our zero point.
07:01 It's really important to take this step very slowly and make sure that we have got our bore gauge accurately zeroed.
07:08 With our bore gauge zeroed we can now insert the bore gauge into the bearing journal on our connecting rod and what we're going to read on the bore gauge is the difference between the outside diameter of our crankshaft journal and the inside diameter of our bearing journal, essentially this is our oil clearance.
07:25 So let's do that now.
07:27 What we want to do here is take our dial bore gauge and insert it gently into the bore, into the journal of the connecting rod and we want to do this perpendicular to the parting line on the connecting rod.
07:38 Once we've got that in there, we're just going to gently rock that backwards and forwards and find the smallest point.
07:44 Now we can see on our dial bore gauge there, it's coming down to 0.05.
07:50 Now it's important to note here that while I have been talking in imperial measurements, the dial bore gauge that we are using just to add a little bit of complexity in there, is actually a metric dial bore gauge.
08:05 So that reading that we just got is 0.05 of a millimetre of five hundredths of a millimetre.
08:12 Remember though it is really easy to convert between metric and imperial measurements, all we want to do is take that measurement and divide it by 25.4.
08:20 Essentially this gives us a clearance of two thousandths of an inch.
08:23 Now this is within the specifications for the factory engine and with our build we'd probably actually be quite happy to run with this.
08:32 If we were making more powerful engines, something with turbochargers or a supercharger, I'd have been inclined to push this out closer to 2.5 thousandths of an inch.
08:42 So again we would go through this process on all of our connecting rods, ensuring our big end oil clearances are within our specification right through the entire engine.
08:52 Let's move on now and we're going to also check out our pistons.
08:56 With our pistons, there's two aspects we're interested in here.
09:00 The first is to make sure that the pistons we are delivered do in fact measure up to what the skirt diameter is supposed to be.
09:07 At the same time, we also want to make sure that our piston to cylinder wall or piston to bore clearance is sufficient.
09:13 Now in most instances, this isn't something that we're going to be able to measure at this point.
09:19 Typically we would be using an oversize piston which would allow our machinist to bore and hone the engine block in order to get a fresh finish on our bore as well as to achieve our desired piston to wall clearance.
09:31 With the LS1 block though, we're limited here.
09:34 We really don't have any ability to bore the block because the liners are so thin.
09:39 And what we're relying on here is the ability to hone the existing bores in order to achieve a fresh bore finish as well as our desired piston to cylinder wall clearance.
09:49 Now this can be potentially a problematic situation with a high mileage engine.
09:55 So this is something we're really interested in checking out.
09:57 Now with our specifications for our Wiseco pistons here, we can see that we have a recommended bore size.
10:04 So this is information our machinist is going to be using.
10:07 Now if we bore our engine block or machine our engine block I should say, to 3.9030 inches finished bore size, this should theoretically give us a piston to cylinder wall clearance of 0.0035 or 3.5 thousandths of an inch.
10:24 Now in many instances, our specifications for our piston will also give a finished skirt diameter so we can straight away use our micrometer and check that our skirt diameter on our piston is in fact what the manufacturer has recommended or suggested they should be.
10:40 In this case we don't have that information but of course it's reasonably easy to calculate that.
10:45 What we'll do is we'll take our calculator, we'll enter our finished bore diameter of 3.903 of an inch and then we're going to subtract from that our bore clearance of 0.0035, this tells us that our piston skirt diameter should be 3.8995 of an inch.
11:04 What we can do now is use our micrometer to measure the skirt diameter.
11:08 It is important though when we are making this measurement to ensure that we're measuring the skirt in the correct point.
11:16 The skirts of the pistons are not parallel, in fact they have a barrel shape machined into them.
11:21 It's only very minor so we can't see this but depending where we measure on the skirt, it is definitely going to affect the accuracy of our measurement.
11:29 If we again check our piston specification sheet we can see that there is a point listed where we should be making this measurement and this is 1.3 inches from the bottom of the oil ring.
11:40 So if we take our digital vernier callipers here and we locate these on the bottom of the oil ring groove, we can see that 1.3 inches comes almost right to the bottom of the skirt and what we can see is that I've actually placed a mark with a vivid marker so that we know where to take that measurement from.
12:00 With that mark located now, we can use our micrometer to make that measurement.
12:05 So I'm just going to open our micrometer up, locate that on the correct spot on the skirt and we're going to tighten that down.
12:22 We can now remove our micrometer from the piston once we've locked the micrometer down and we can check our measurements and we can see that in this case, the piston skirt does measure up exactly on Wiseco's specifications.
12:35 So we know that our piston is on the correct size.
12:38 Of course again we're going to go through and measure each of the piston skirts to make sure that they are all on the correct size.
12:45 Once we've done that, we're now in a position where we can measure our bores in our block and find out if we are seeing the correct clearance there.
12:55 Now in this case though we are going to need to be able to remove a little bit of material with the honing process so we know that our finished bore size should be 3.903 of an inch.
13:06 In the perfect world, we'd like to be a little bit under that, perhaps around two thousandths of an inch under that and this will give us enough material for the machinist to be able to achieve that correct bore finish.
13:19 So ideally at this point, we should be seeing somewhere in the region of a 3.901 inch bore with our finished bore diameter in our existing engine block.
13:30 In turn, this should be giving us a piston to cylinder wall clearance at the moment of somewhere around about 1.5 thou.
13:38 Again this just gives us a little bit of material to remove to get us to our desired clearance of 3.5 thou.
13:45 What we're going to do now is we'll bring our engine block in and we can use our dial bore gauge to go through the process of checking all the bores.
13:53 We've got our engine block set up on our stand and we're going to go through the process of checking our piston to bore clearance on one of the cylinders.
13:59 We've got our dial bore gauge, I've adjusted this and I've zeroed it using our micrometer.
14:05 So remembering here what we're hoping for is that our piston to cylinder wall clearance should be around about 1.5 thousandths of an inch or less.
14:14 Also remembering here that our dial bore gauge is a metric dial bore gauge.
14:18 So what I'm going to do is take the bore gauge and I'm going to fit it into our bore for number one cylinder and what we want to do is check our clearance as we move the dial bore gauge up and down the bore.
14:31 So it's important to rock it backwards and forwards through the narrowest point here but we also want to make our measurement up and down the bore and this allows us to see if there's any taper or any belling in our bore so we'll just go ahead and do that now.
14:45 So at the moment the measurements we're seeing are well within our specification.
14:49 We also want to make one more check though, we also want to turn our dial bore gauge through 90 degrees and we want to check perpendicular to our first axis.
14:59 So this just allows us to measure any out of round that we may see in the bore.
15:04 So with our clearances checked on number one cylinder, we're seeing a maximum reading there of about two hundredths of a millimetre of 0.02 of a millimetre.
15:13 Now remembering we do need to convert this across to imperial.
15:16 So two hundredths of a millimetre works out to be about 0.8 of a thousandth of an inch or eight ten thousandths of an inch.
15:25 So this is well within our specification there, it actually means that there is a relatively low amount of wear in this engine, despite the fact that it does look like the mileage is high.
15:35 Of course we'd go through now and check our bores for the rest of the cylinders as well just to make sure that everything measures up.
15:42 And at this point, we are comfortable with everything we've measured, we've done all of the checks that we're capable of doing here in the workshop, it's time now to ship all of the components off to our engine machinist for the machining work to be completed.

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