Stock engine cases (blocks)
-Written by Steve Phillips for Hot WVs Magazine-
As I rack my brain, deciding on the topic for the next article, I find myself distracted, daydreaming about blocks and how I can get my hands on them. As other people in the industry know, trying to get new, stock engine blocks this last year has been a joke. I was able to get 3, in July, but haven’t been able to get any since. There are many rumors about what’s going on, but the bottom line of what I’m hearing is that we’ll be lucky to see any, until 2023. And that’s if at all! Now, what’s a guy to do? Unfortunately, I don’t have the most optimal answers. The best I can suggest is to pay close attention to this article, in which, I will be talking about dual relief cases. For more information on why I use these cases, see my article “Case Logic”. Please note that the following does NOT apply to Type 4 cases (1972 Air-cooled Bus). Type 4 cases rarely have issues, so consider that your relief!
Here is what’s out there now: Autolinea All-Aluminum and FT-1 All-Aluminum. There are others, but these are the closest to stock. Autolinea is a foreign manufacturer, and the FT-1 is made right here, in the states. Both options are much stronger than the stock cases. Does that mean this a better way to go than the stock case? I can’t answer that with a definite yes or no. What I can tell you is this; If you’re building a Friday/Saturday night car or a sand rail motor, then I would say yes. For a daily driver, I can’t say the same. Here’s a little story; When the Autolinea first came out, I built two daily driver motors with them, and they are still running today. We have gauges, coolers, deep sumps, etc. on them and they have never been overheated; however, they do run hotter than a stock block. That is my concern. After I built those two, I went back to the stock blocks for a daily driver. Heat is our enemy on a daily driver and I do everything I can to keep heat out of the motor. One last note on the Autolinea cases (and this is an important one); you NEED to check the oil holes that feed the main bearings. I have yet to find one that lines up correctly. We end up having to use a Dremel tool to oval out the passage so that it lines up with the main bearing groove. I found this out years ago the hard way. As for the FT-1 case, I have yet to build a motor out of them, but I know many people who have, and they like them a lot for racing.
Although that helps us to know what cases are out there, it still doesn’t help with what’s available to us, now. Raising the question: What is a guy, or even a shop, to do about getting cases? Well, I’m thinking the price on good, used dual relief cases is going to go up and if we want to run a magnesium stock case, we will have to resort to used cases. What’s wrong with used cases? Nothing, if it’s in good condition. Admittedly, it’s hard to find good a good case that hasn’t been overheated. But who cares if it has been overheated? You’re rebuilding it anyway as long as you inspect the following.
One of the first things to check on these used cases is the Align bore. Has it been bored? Does it need to be bored? If you can feel a groove or a ridge as you drag your fingernail across the main bearing saddle, then yes, it will need to be bored. Align bore sizes are STD, .020, .040, .040, .060, .080 and .100. If this is a motor being built for longevity, then I prefer to stay .040 or less. People go for more all the time, but from my experience, .040 or less is the way to go.
Now, let’s get into a problem we frequently find with these used cases, making it even more important to inspect. That’s right, cracks! I’m going to discuss the most common areas that you will find them. The first, is behind Number 3 cylinder. If you clean it well and then look hard at the back of the case, you might find this crack. It’s not the area about this one that makes it bad, it’s where it will end up. It always finds its way to an oil galley plug. When the plug falls out, guess what? You won’t have any oil pressure, but you will have a wet flywheel and clutch. If you’re looking at a case and the oil galley plug is missing, you probably guessed correctly. It’s cracked. I have seen guys weld this up, but I have yet to see it hold for long. My opinion, it’s a dead player. Another problem area is the oil pressure sender hole. This is an NPT thread which means it’s a tapered thread. People over tighten this oil pressure switch and crack the block here. I have seen this welded, and it does seem to hold okay. If the case has been drilled and tapped for full flow, it’s an NPT thread fitting and can easily be overtightened, cracking the case. One of the “not so obvious” locations is on the cylinder numbers’ 3 & 4 side. You can’t spot this one, unfortunately. There is an oil galley that comes from the oil cooler, down to the main oil galley that feeds everything. The galley is close to Number 4 head studs. Sometimes, the threads of the case saver will crack into that galley. If it’s cracked, when the motor heats up, oil will leak out of the head stud. I have seen guys try and fix this one, but I usually end up starting over with a new case.
What I see more than anything when these cases get over heated, is something we call a spread center main. What is a spread center main? Let’s look at the inside of the case… We are concerned about the three large main bearings. The rear main bearing is supported from top to bottom and is a one-piece bearing. It feeds the number 3 cylinder connecting rod. The large bearing towards the crank pulley (not the small nose bearing) is also supported from top to bottom and is a one-piece bearing. It feeds the number 2 rod. All good and rarely ever problems with these bearings. Now, let’s look at the center main bearing. This bearing sits in a saddle that’s an island in the case. It’s not supported at the top nor the bottom. So what? Well, being as it is not supported, it can move! Not much, but it does, especially, if the motor gets too hot. It feeds Number 1 and Number 4 connecting rods and is a two-piece or “split bearing”. That’s right, it’s unsupported, and does more work than the other bearings! Now, we can circle back to the spread center main. Oil comes from the case’s oil galley and travels around the outside of the main bearing before it finds the hole that feeds the crank. The crank is designed with holes that feed the oil to the rods. If you have a spread center main, you will have oil pressure when the engine is cold as the oil is thick. As the engine heats up, the oil thins out and finds the split in the case and leaks through that split back into the sump. In other words, it’s bleeding internally. This limits the supply of oil that is going into the crank, which in turn, limits the supply of oil to the two connecting rods. We all know what happens when you starve a rod bearing… As you can see, this is a weak area in these motors. How do I check for a spread center main? There is no fail-safe way. A bad case is easy to spot, but a marginal one is not. My advice is to inspect the area where the halves meet (from the main stud to the bearing). If it’s shiny or a different color than the rear, I know it has been walking or separating. In other words, they’ve been rubbing against each other, and this will cause a gap between the halves. Another way to tell is by putting a straight edge across the flats of the three large main bearings to see if you can spot daylight between the center saddle and the straight edge. Keep in mind, this area can tighten up when you bolt the halves together, so it isn’t the best way to test. Another way to test is by bolting the two engine halves together and torquing them down. Now, take your flashlight and shine it on one end and look down the other. If you see light, that means there is a separation. The downfall to this test is when the motor heats up, this can separate and leak internally. So, what is an engine builder to do?
Let’s talk about shop nature and who’s liable. Say a shop builds your motor out of a used case. Either yours or one the shop has sold to you. You get the motor, warm the engine, but you find you either have low or no oil pressure due to leakage somewhere. Who pays? The shop? You? At my shop, if a case is marginal, I leave it up to the customer. I tell them, “You can save money by using your case but if we have a problem, I’m not going to tear it apart and put it back together for free”. This has the potential to get pricey when building a large motor, like a 2007cc. That may require having machine work done to the case and that is a tall bill. Who pays for that? Not only did the customer pay for the machine work to the old case, but he will have to pay for it again on a different case. Labor, what about that? You paid to have an engine built and now you have to pay again? On a new case, chances are slim that we will have any problems, but with lack of availability, do shops and people start using the all-Aluminum cases? Maybe, but not my first choice.