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Practical Engine Building: Step 4: Block Preparation

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Step 4: Block Preparation

11.16

00:00 - We've got all of our engine components now back from our machinist and we've got our SR20 engine block set up on our engine stand here.
00:08 We're going to go through some of the processes that we will apply during the block preparation step.
00:14 Now this is going to start by removing all of our oil gallery plugs, this is going to allow us complete access to all of those oil galleries so that later on when we get to our cleaning step where we're cleaning all of our engine components down we can be really certain that there is no dirt or debris trapped in any of those oil galleries, this could quickly damage our freshly built engine.
00:36 So there are a number of gallery plugs on the front of the block, the side of the block as well as the back of the block, and we're going to go ahead now and remove those.
01:07 With all of our gallery plugs now removed, the next step of the process is to run a tap through the critical fastener holes on our block, including obviously our head studs and our main stud holes.
01:18 Now to do this I'm going to be using a bottoming tap and this allows us to clean those threads all the way to the bottom of those blind holes.
01:27 In order to do this I'm also going to be using a cutting oil to help lubricate the tap and make sure that the finished threads are nice and sharp, and there's going to be no damage on those threads.
01:38 So let's get started now and we're going to begin with our head stud hole and I'm using an 11 by 1.25 millimetre tap here.
01:47 We've got our cutting oil and I'm just going to apply a light spray of that cutting oil down the thread hole as well as to my tap, and then we're going to insert our tap into the hole in the block, and just get it started.
02:02 Now when our threads are in relatively good condition you can see there's a limited amount of tension or friction on the tap so it's quite easy to wind in.
02:11 If we've got a threaded hole that's not in quite such good shape, then we're going to find that we're going to be needing a little bit more force on the tap, it's also a good idea to rotate the tap backwards about every turn or two turns and this just allows us to clean the threads and remove any debris into the flutes of the tap.
02:31 Alright so that's our first hole tapped there.
02:35 We're going to go through now and complete the process on the remaining holes.
04:00 At this point we've gone through and we've tapped all of the head stud holes.
04:04 Now we're going to flip the engine block over here on our engine stand and we're gonna repeat the process for our main studs, so let's go ahead and do that now.
04:16 Our main studs are going to be using the same 11 by 1.5 millimetre tap, however you can see that because the main stud holes are recessed down below the sump rails, this is going to make it impossible for us to get good access using the conventional t handle that we use with the tap for our head studs.
04:36 In this case a nice little trick that I like to use is to find a quarter inch drive socket that's a snug fit on our tap.
04:42 Then we can use an extension and we can use a quarter inch drive strong arm and this will allow us to easily insert and remove the tap.
04:51 So let's go through that process now.
06:00 Alright so we've gone through there and we've run our tap through all of our mission critical fastener holes.
06:05 Of course depending on the condition of your block and the remaining holes on the block, it can also be worthwhile to go through and tap the remaining holes on the block.
06:15 This is going to for example make sure that when you get to a point when you're tightening up engine mounts or external components on the engine block, that you don't end up breaking off a bolt because there's debris or corrosion inside one of the external bolt holes.
06:29 In our case we're going to move on from here though.
06:32 In the next part of this process we're going to look at de burring the block.
06:36 So all we're going to do here is remove any sharp edges.
06:39 We're also going to be removing any signs of casting flash, anything on the inside of the engine that may break free, potentially while the engine is running.
06:48 Now in this case because we are dealing with an aluminium block, there isn't a lot of casting flash, it is actually relatively clean.
06:55 So what we're going to do here is use our die grinder and go across all of those sharp edges on both the underside and the top of the engine block, and break down all of those sharp surfaces to de burr them, so let's go ahead and do that now.
07:09 To start with I'm going to use the die grinder and just remove the sharp edges on both the inside and outside of the sump rails.
07:50 So with some work done to our sump rails there we can also look a little bit deeper inside the engine block and see if there's anything that needs our attention.
07:57 In particular we can see up around the front of the engine block here, we've got a few sections where there is a little bit of casting flash, and it's always a good idea to remove that casting flash and just smooth things over.
08:09 So we can use our die grinder there, we can also switch to an air die grinder depending on exactly how much material we want to remove.
08:18 So we're not trying to do anything drastic here.
08:20 We just wanna remove anything that could end up breaking off in operation, and just smooth over any sharp edges, so let's continue.
08:57 Alright so we've cleaned up everything on the inside of the engine block there.
09:00 And you can sort of see the kind of surface finish we're trying to achieve there.
09:04 Again we're not taking out excess amounts of material, we're just trying to smooth off those edges and make sure that there's nothing sharp that could break off.
09:13 So with everything done on the underside of our engine block, we're going to now flip the block over and we'll repeat the process on the deck surface.
09:22 On the deck surface of the block we're going to repeat the same process we've just looked at.
09:26 We're going to be just taking off any sharp edges that have been left as a result of the deck surface being milled during the engine machining processes.
09:34 We're gonna do this around the outside edge as well as internally around any of the water jacket holes or oil gallery holes.
09:40 Clearly we need to be very careful when we're doing this to make sure that we don't slip and end up scratching or gouging that deck surface of the block.
09:48 That's gonna be critical to our head gasket seal.
09:51 So let's go ahead and do that now.
10:23 Alright with the majority of the work done there using our little Dremel die grinder, there's another option that we can also use which can be a little bit easier, particularly on perfectly circular holes and that's to use a metal working de burring tool and we can simply run this gently around the inside edge of these round holes and this will chamfer the surface.
10:43 This is great for example for round holes for our water jacket, as well as the holes for our head studs.
10:50 So let's go ahead and do that now.
10:56 Alright so at this point we have finished the block preparation, there's nothing more for us to do here.
11:00 In a conventional cast iron block we'd of course take the opportunity now to paint the block, however with the aluminium block we're traditionally going to leave these in their bare surface condition.