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Practical Engine Building: Step 3: Engine Machining

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Step 3: Engine Machining


00:00 - The next step of our process is of course the engine machining and clearly we're not going to be doing that ourselves however before sending our parts out for machining, there are still some checks that we can take, some measurements we can make basically to make sure all of the parts are where they need to be in terms of their specifications and dimensions.
00:19 We can also go some way to measurement our bearing clearances to get an understanding of where our clearances are going to be.
00:26 It's worth doing this before we send the parts to machining because if we find in particular our bearing clearances aren't on the specification we want, then this allows us to work with our machinist in order to find a solution.
00:40 Whether that is an oversize bearing, whether it's polishing the crankshaft journals or any of a range of other options that can get us where we need to be.
00:49 We can't at this point do anything with our pistons in terms of checking piston to cylinder wall clearance because we are moving to a first oversized piston, this means that the engine block needs to be machined before we can actually check that clearance.
01:05 The other aspect here that we're going to have a look at which is a common problem in alloy blocks is whether fitting an aftermarket stud kit is going to actually result in any distortion in the main bearing tunnel.
01:18 This is something that's easy to overlook when we're fitting something like an ARP aftermarket stud kit.
01:24 This does provide more clamping force by virtue of the superior material these studs are made out of compared to the factory main bolts.
01:32 What this can do is actually distort the main tunnel and this will affect our bearing clearance, if we don't know that that's happened it can be difficult to get our clearance where we need it to be.
01:43 The clearance of course isn't going to be consistent and this can quickly result in bearing damage when the engine is assembled and run.
01:49 This is more usually a problem with alloy blocks but we are still going to have a look at what happens with our cast iron block, our 4G63 and have a look at the measurements we take just to ensure that there is no distortion with everything installed.
02:04 What we're going to do here is start though by measuring our crankshaft.
02:09 So we've got our Manly billet stroker crankshaft here and I've also got the factory workshop manual for the Evo 9.
02:16 It's always a good idea just to start by comparing the specifications of our crankshaft to the factory workshop manual.
02:23 So what we're going to do is start with our big end bearings, I'm going to use my micrometer here and I'm going to measure the big end journal.
02:33 Looking at the factory workshop manual, we can see that the minimum journal diameter is 1.7709 inches and the maximum journal diameter is 1.7717 inch.
02:44 Now between that there's actually 3 different grades that the factory crankshafts are separated into and this is used for Mitsubishi's own internal blueprinting by choosing the correct bearing grade based on the grade of the crankshaft journal, this allows us to get the bearing clearances where Mitsubishi recommend.
03:04 Of course we may want to make some variations from Mitsubishi's specifications there but that's just how that works.
03:12 Let's get started and we'll take a measurement.
03:14 What we're going to do is take our micrometer, locate it on the crankshaft journal and we can find the largest diameter of that journal and we'll just tighten that using the little thimble at the end.
03:25 We can now lock it up and remove it from the journal.
03:28 I have only taken a measurement in one location here.
03:31 Typically what we'd actually be doing is taking multiple measurements on that journal.
03:35 I like to take two at perpendicular angles to each other and it's also a good idea to measure at each side of the journal.
03:44 This allows us to check that there's no taper present on the journal and it also allows us to check that the journal is perfectly round, in other words we're not measuring any out of round.
03:53 Now taking our reading there, we can see that the journal I've just measured, number 1 big end, is 1.7713 inches.
04:02 Now if we refer that back to the factory workshop manual we can see that this actually makes that particular journal a grade two.
04:10 So we've measured our first big end journal, we know that we are within Mitsubishi's specifications so this is always a good start.
04:18 Of course now we'd go ahead and measure the rest of the journals.
04:22 I've already done that ahead of time and in this instance, they all actually measure up at exactly that same measurement, they're all a grade two.
04:30 So our big ends are in good order, we know that the crankshaft is fine as far as the big ends are concerned.
04:36 Next we're going to move on and have a look at our main journal diameters and again from the factory workshop manual, we can see that the specification there is a minimum of 2.434 inches with a maximum of 2.441 inches.
04:49 And again this is separated into 3 grades for exactly the same purposes.
04:54 What we'll do here is we'll take our micrometer, this time I'm stepping up to a larger size micrometer and we're going to do exactly the same job here again.
05:09 Locking up our micrometer there and checking our measurement, we can see that the number 1 main journal there is 2.2432 of an inch.
05:18 Now that's actually slightly outside of Mitsubishi's recommendation.
05:23 It's actually very slightly smaller.
05:26 Now that may or may not be a problem depending on what our bearing clearances actually measure up but it is a little concerning that a brand new crankshaft here is actually outside of specifications and this is just one more indication why we should always trust but verify our measurements, it's always worth checking and never assuming that just because you bought a name brand component, that it is exactly what the manufacturer has said it will be.
05:51 I've already gone ahead and measured the remaining main journal diameters and essentially they're all very close to what we've just measured, the smallest, the one we've just measured, 2.2432 inches, the largest, 2.2434 inches.
06:04 Interestingly even the largest journal there is still very slightly outside of Mitsubishi's minimum size specification.
06:12 Now we can go ahead and check our big end clearance.
06:15 In order to do this, I'm going to take our Boostline connecting rods and we can dummy assemble them with the ACL Race Series big end bearing shells installed.
06:24 Just a note here, we are running a custom age 625 fastener.
06:28 There's a couple of aspects we need to be mindful of.
06:31 Due to the type of material we use with these custom age 625 fasteners, it is important not to touch them with your bare hands.
06:38 They can suffer from hydrogen embrittlement which can result in them failing so we always want to use gloves when we're actually contacting the fasteners themselves.
06:47 The other aspect here is for maximum accuracy when we are tightening these fasteners down, instead of using the torque method, we do, wherever possible actually want to use a stretch gauge such as this one here from ARP.
07:02 The stretch gauge physically allows us to measure the stretch of the fastener which is a more accurate way of tightening the fastener.
07:10 Really this is what we're trying to achieve when we are torquing the fastener down, we're just trying to achieve a specific amount of stretch in this fastener.
07:18 In this case the ARP custom age 625 fasteners recommend a stretch between 6.7 and 7.1 thousandths of an inch which is exactly what we've achieved.
07:28 What we're going to do now is zero our dial bore gauge in the jaws, or between the anvils I should say of our micrometer.
07:37 You'll remember this is still set at the outside diameter of our journal for our crankshaft.
07:43 This makes it nice and easy because in this case, all of our big end journals actually measured up the same.
07:49 So we'll go ahead and do that now.
07:51 Remembering what we're trying to do is essentially find the largest diameter as we're rocking this backwards and forwards between the two anvils and we want to zero our dial bore gauge at that diameter.
08:02 Once we've got our dial bore gauge zeroed on the outside diameter of the crankshaft journal, the dial indicator is now going to show us our actual bearing clearance when we install it into the big end of the connecting rod.
08:14 It's also a good idea to obviously have an understanding of what we're actually aiming for with our bearing clearances here.
08:19 The factory workshop manual recommends a clearance between 1.2 and 2.0 thousandths of an inch and that range will work really well for most applications.
08:30 Given that we are intending to push a lot more power and a little bit more RPM than stock, I'm going to try targeting closer to the 2000ths of an inch range of that specification.
08:43 So what we'll do now is take our connecting rod and we're just gently going to insert the dial bore gauge into the bearing journal and we can just rock that backwards and forwards here through the central point and we can see that we are getting, in this case exactly 2000ths of an inch.
09:00 So that's a pretty good indication that we're where we need to be.
09:04 Of course we would also go ahead and check the remaining big end bearings, making sure that all of them are on our specification and in this case everything is looking pretty good, so we know our big end clearance is where we need it to be.
09:18 One more check that we can do with our crankshaft and our connecting rods is to check the side clearance of the connecting rod and this is a measurement that is quite often overlooked.
09:28 Again a lot of people just assume that the conrods will provide the correct side clearance.
09:33 Always worth checking and this is a measurement that is a little bit less critical than some of our other measurements.
09:40 Again, checking the factory workshop manual, we can see that the factory side clearance recommendation is between 4 and 9 thousandths of an inch.
09:48 So to do this, all we need to do is take one of the caps from our connecting rods and we're just going to lightly install that onto the crankshaft journal, we don't need a bearing installed in order to do this, and we're going to take our feeler blades.
10:02 In this case I've got my 4 thou feeler blade and we'll just slide this down the side of the cap and I know that I've got a reasonable amount of clearance above that, it's quite loose in there.
10:13 At the other end, we'll take our 9 thou feeler blade and we'll see if we can get our 9 thou feeler blade in here and in this case we can't, our clearance is definitely less than 9 thou so that's all I really need to know in terms of that particular clearance, we know that we're within that factory clearance range and again this particular clearance, as long as we're within that range, it's not quite as critical as the other bearing clearances that we're talking about here.
10:41 Alright what we're going to do now is check our main bearing clearance and in order to do that we're just going to rearrange the studio a little bit and bring the engine block in, so let's get that done.
10:53 Before we actually check our bearing clearance, we're just going to go through the process of a dummy assembly here to see if we are ending up with any distortion in that main bearing tunnel thanks to the ARP fasteners.
11:04 So I've gone ahead and assembled everything, just like I was assembling it for the final time.
11:10 We've torqued the ARP main studs down to ARP's recommendation of 60 foot pounds of torque using the ARP moly lubricant.
11:18 We've got no bearing shells installed at the moment.
11:20 And what we're going to do is use our dial bore gauge and we're going to basically be checking the bores in multiple planes and if everything is still true, we should find that everything's nice and round, so what we're looking for is any indication that when we check in different planes, that the bore gauge is no longer coming back to our zero point.
11:42 If that's what we're seeing then obviously we've got some distortion going on in there and we'd want to have that addressed by our engine machinist through the process of align honing.
11:51 So let's go ahead and check our front bearing journal now.
12:03 So what I'm doing here, I've just zeroed the dial indicator and we can see that as I rock it backwards and forwards, perpendicular to the parting line of the bearing journal, we are just contacting that zero, so that's exactly what we'd expect to see there.
12:19 We'll now install it at 45° and we'll see if we've got the same indication and as I rock it backwards and forwards we can see we're still coming back through zero so no distortion showing in that plane.
12:32 We'll do exactly the same, turning it the opposite way, 45°, still coming back through zero so no distortion.
12:39 And then we can get pretty close to being in line with the parting face and check again.
12:44 And when we do this in line with the parting face we do want to be just a little bit off the parting face, otherwise we're going to struggle to get a good reading.
12:53 Again we've got zero distortion showing there so obviously I've only checked one journal, we'd go through and check all 5 of our journals but at this point everything is looking good.
13:04 And this is usually what I'd expect to see with a cast iron block but again it's always a good idea to actually measure and check, it's a very quick test to do.
13:13 What we're going to do now is disassemble the cradle, remove that and we'll install our bearings so we can check our bearing clearance.
14:42 Alright we've gone ahead and installed our ACL race series main bearing shells and we've retorqued our ARP hardware, tightening back down our main bearing cradle.
14:51 What we're going to do now is we'll take our dial bore gauge again.
14:55 I've already gone ahead and zeroed this using our micrometer set to the outside diameter of our crankshaft main bearing journal and we're simply going to install this into our bearing shells and we'll see what our bearing clearance is.
15:09 When we are doing this, we want to make sure that we are taking our reading at 90° or perpendicular to the parting face of the bearing cap.
15:18 So let's go ahead and do that now.
15:27 Alright we've got our dial bore gauge installed there, just rocking it backwards and forwards past the narrowest point and we're getting a reading of 2000ths of an inch there.
15:37 And that's actually about where I want the bearing clearance to be for our main bearings.
15:43 Before we go further though, it is always a good idea to understand what the workshop manual calls for here.
15:49 The standard clearance is between 1.2 and 1.5 thousandths of an inch.
15:53 That's actually quite a narrow range, the maximum clearance that is allowable from the factory workshop manual is 3000ths of an inch.
16:00 Now again given that we are building an engine that is going to be making substantially more power than stock and it's going to be revving a little bit higher, I'd like to increase that clearance a little bit.
16:11 Given my own experience building a number of these engines for high powered applications, normally I end up with my main bearings around about 2 thou, or at the upper range for our drag racing applications, we were running between 2 and 2.5 thou.
16:26 So for our application, given that we will also be running thicker viscosity oil, more than happy with my clearance there at 2 thousandths of an inch.
16:35 Now of course at this stage we have only made that measurement on our number 1 main bearing journal, of course we'd rinse and repeat that process across the remaining 4 journals, making sure that all of our clearances are within our specification and where they need them to be.
16:48 So at this stage, we've basically taken all of the key measurements that we can at this point, I'm comfortable with the oil clearances on both the big end and the main so there's no requirement here for any manipulation from our engine machinist.
17:02 At this point we're essentially ready to pack up all of our components and send them off to our machinist and we'll be able to move on with the next step of our process.

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