I tried to document all the major steps I put into building my 2176 motor, hopefully some of it will be useful to someone...

One of the first things to do is to check main bearing clearances. Don't assume that just because you were told your main crank journals were such-and-such a size (say .010" smaller than std) and that you bought the right bearings that your oil clearances are going to be right. In my case, I had to buy a second set of bearings (Kolbemschmidts, the good stuff) to get a #4 bearing I was satisfied with and I had to do a little work to the #2 bearing saddle on the case to get that bearing right. I was aiming for .0025-.003" radial oil clearances on all the mains. In the end they were all about dead on, but if I had just slapped it together w/o checking things I would have had really tight #'s 2 and 4 bearings, which could have seized. The most accurate way to determine oil clearances is with the use of a properly calibrated dial bore indicator for the bearings and a micrometer for the journals. If you use the same micrometer to calibrate the bore indicator that you use to measure the journals your numbers should be accurate. The journals are self explanatory, and I measure each every 45 degrees and record those numbers. They will not be "perfectly" round, so you want to know what the max and mins are for each journal. For the bearings, you want to put all 4 main bearings in the case and torque the case halves together so you have the proper bearing crush. Make sure everything is absolutely SPOTLESS when you are assembling it, a tiny piece of dirt between the saddle and bearing can really throw off the readings. I also measure each bearing every 45 degrees and write down all these measurements. So here's what measuring the main bearings looks like:

Calibrating the dial bore indicator:


Measuring bearing #1


Main bearing #2



Main bearing #3



Main bearing #4


Once you have all journal and bearing measurements written down, compare the pairs to find the minimum, maximum, and average oil clearance for each journal/bearing set and make sure they are within your desired tolerances.

The next thing I do is to check how well the oil grooves or holes in the bearings line up with the oil galleys in the case. You'd think they would line up nicely, but it is not uncommon for them to be pretty far off. If they are off far enough it could limit oil flow to that bearing, not a good thing. So I check each bearing mad make sure there is good alignment and modify the bearings as necessary.

First I measured the location of the oil galley for the #1 bearing and marked it on the bearing, along with an area to blend it in with the original groove. You can see from where it's marked that about half of the oil galley was blocked by the bearing


The #2 bearing was about 1/3 blocked, not too bad...


The #1 bearing with modified oil groove


The #3 bearing needed about the same amount of midification


Scribe lines on the #2 bearing locating the oil galley


Its hard to see in the picture, but the bearing hole on the saddle side of the bearing is stretched to meet the oil galley hole in the case



Next comes the cam. Basically I do this the same way I do the main bearings and journals, although it's obviously a lot less critical, It's still good to make sure everything is within tolerance

Measuring cam bearings with the dial bore indicator, I do this with the main bearings in the case and the case torqued down to spec. Same procedure as the main bearings, 4 measurements per journal and bearing, then compare...


The thrust bearing is basically too long as it comes so you have to modify it to achieve the proper thrust clearance for your particular cam. Only do this on one thrust surface of each half of the thrust bearing, and make sure it is the same side of both. Basically just try to apply even pressure on some medium grit emery paper, I like to take measurements pretty often to make sure I am taking material off evenly, and that both halves end up the same. You can measure your cam and then subtract your target thrust form that number to determine the size you need to make the bearings...




Checking cam thrust. I set it at about .003"


This is a good time to check total lift at the cam....



Also check cam to lifter clearance, I wouldn't want less than about .060" or so...



This is probably a good time to check for cam gear bolt to oil pump clearance. You may need to grind you cam bolts or oil pump housing a bit, in my case I had to grind the pump housing a little to get enough clearance. I think to start with I had like .016" clearance, and I ground the pump till I had like .040-.050", which should be plenty...


Measuring clearance with a feeler gauge...



You can see here when I did some grinding on the pump body...


I also blueprinted the oil pump into the case. Same basic procedure as bearings, torque down the the case, measure every 45 degrees, and measure the pump every 45 degrees. Compare corresponding diameters, you want a nice tight fit with out too much slop, but you also don't want it to be impossible to get the pump in the case. about half to one thousandth should be fine...



One of the next things I did was to pull the case plugs out and replace them with pipe plugs. The advantage of this is that you can *really* clean all the oil galleys in the case. There's just no way to really get all the crap out of them without having the plugs removed. There will be metal shavings that collect in the oil galleys from any machining you had done on your case if its a new case, and if its a used case, well, who knows what lurks inside there. Better to open it up and and then *know* theyre clean. Easiest way to get the aluminum plugs out is with a slide hammer with a sheet metal screw on the end. Drill a hole in each plug, thread the screw into it, attach it to the slide hammer, then give it a good tug, it will come right out...



Drill and tap the holes with the appropriate drills and taps (I'll look up the sizes later and add them)





For full flow applications you want to tap and plug the oil inlet on the case from the pump and the oil outlet of the pump.




Depending on the tap you use, you may not be able to go deep enough on the pump body for the plug to be sunk in far enough. No big deal, just grind the outside of the plug as needed...



The case with all the plugs installed. Use a teflon automotive thread sealant to seal these, I found out the hard way that Curl-T does not make a good thread sealant...






The next thing is a little detail I like to do that most people never think of, and that is making sure the oil pressure relief plunger has a nice surface to seal against. If the plunger does not form a good seal oil and hence pressure will leak past it and your oil pressure will not be as good as it should. Aircooled.net sells a tool for cleaning up this surface and it works quite nicely.


Here's what the surface looked like on my new case. It's hard to see, but there is a step around the edge of the surface that the plunger would have hit and formed a terrible seal against.


Loosen the collar on the tool, put it in the hole so it bottoms out, then put a .010" feeler gauge in as shown and lock down the collar...


Turn the tool by hand with a pair of vise grips or what ever till you have taken off .010". Visually inspect the surface you just cut and repeat until you have a nice flat surface for the plunger to seat against. Keep track of how much material you removed, then shim your spring accordingly to achieve the proper pre-load on the spring


To really make the surface nice I glue a piece of sand paper to the top of a plunger then I lap the surface with it till it's nice and smooth...




That's all for now, but there is plenty more where that came from. I have photos of about every step and will continue the writeup later...

Doc,you sure know your stuff....I wish I was that talented!!!

Thanks bro! I love this stuff though, I can totally geek out on it

Very nice write up!

Nice write up. Hard to comprehend all that at once though .

Good info there Brian! Thanks for sharing!

Here's my next installment

New cases seem to come with horrific oil pickup tubes. In the case of mine, it was situated very crooked in the case, and from what I hear this is pretty common



Well, that just wouldn't do. I had an old VW case laying around that I stole the pickup tube out of, you can see the difference between the crappy "new" one and an original German one...



The German one was a bit long for the new case, so I trimmed it as needed.


The oil pickup tubes are basically just a press fit into the case, so to install a new one you just carefully tap it into place with a rubber mallet, then attach the tab on it to the stud in the case


Since I was going to run a deep sump, I had the pickup tube extension TIG welded on to the pickup tube, no chance of it coming loose now. Since my motor is full flow filtered I elected to not run the cheesy metal mesh "filter", so the extension length was made accordingly. If you are going to be building a motor that routinely revs over 5K RPM I would strongly suggest going full flow filtering and ditching the mesh, they have been shown to be restrictive at high flow rates.


Another thing I checked was clearance between the case and the 1.5 qt sump I was planning on running. Luckily I checked this, there was interference between the tab on the bottom flywheel end of the case and the sump, as you can see in the picture below. No big deal, I just ground down that tab till there was adequate clearance. But If I hadn't caught it at this point I may not have and it probably would not have sealed well and caused a big oil leak.



Next its on to the rod bolts. For a performance motor you really should go by rod bolt stretch rather than just torque. Think of a rod bolt as a spring, when you stretch it by a certain amount, it creates a corresponding amount of force, providing you are within its elastic range. It's that amount of force, which is proportional to the amount of stretch, that is important to hold the cap on the connecting rod. The way you stretch a bolt is by torquing it down, but unfortunately there are just too many variable that affect the relationship between torque and bolt stretch to just go by torque alone. For example, my particular rod bolts, which are ARP2000's, they list the recommended torque to be something like 25 ft-lbs (I can't remember the exact number) when using ARP rod bolt lube to achieve the desired stretch of .005". When using regular motor oil as the assembly lube, the number jumped by around 10 ft-lbs! Just goes to show you the relationship between torque and stretch is very sensitive to something you might not think would make that much of a difference. The only way to know you have the right amount of stretch is by measuring it. To measure it you just need a micrometer. For each rod bolt, measure its length from end to end (the ends need to very flat to do this, otherwise there are special tool available to do it). You then lubricate the bolts, put them in the the rod, and start torquing them down. Snug both bolts down about the same at first, then start torquing them both down in maybe 5 ft-lb increments till you start getting close to the recommended torque level. At this point, measure each of them and subtract their free lengths and see how much stretch you have. Continue torquing them a ft-lb or two at a time and measure the stretch after each step till you get to the recommended amount of stretch. Record the value for each rod bolt, sometimes there will be a ft-lb or two difference between bolts. Keep the same bolt with the same rod and in the same location. It's a good idea to go through this series of steps a couple times, usually the amount of torque required to achieve the target stretch will go down a little after the bolts have been cycled a couple times. Keep very detailed notes, it will pay off later. Also, after each torque cycle of each rod bolt, measure it's free length again and compare it to the original value. If the free length changes my more than a certain value (as specified by your rod bolt manufacturer) then the bolt is junk.

Torquing down a rod bolt. Hold the rod in a bench vise with soft jaw liners (aluminum is fine) so you don't mar the rod side surfaces


Measuring rod bolt stretch...


My threads were not real smooth, so I ran a tap through them to clean them up and get more consistent torque readings...





Similar to the main and cam bearings, measure the rod bearings with the rod bolts torqued up and compare it to measurements of the rod journals on the crank, again taken every 45 degrees. Make sure you have proper oil clearances...


You also need to check the side-to-side clearance of your rods and rod bearings when the rod is hung on the crank. Put the bearings on each rod piece and put them on the crank journals. Torque them down. You don't have to go all the way, I found that for mock up proposes 20 ft-lb or so is enough to get proper bearing crush. Measure side to side clearance of the rod on the crank using a feeler gauge. If I recall correctly you want .016" side clearance (I'll double check later).

If you have less then the target amount either your rids need to be ground down or (more likely) you bearings are interfering with the radii on the crank's rod journals. If this is the case you need to put a radius on the edges of the bearing shells to clear the radii on the journals. Use a small file and remove a little material at a time....

Once you have the main bearings all sorted out, it's a good time to try some mock-up assemblies. First I like to try the crank by itself. If you haven't done this already, put the #'s 1, 3, and 4 bearings into the case half that has the dowel pins and seat them all the down on the saddles. Now take an awl and gently score a line on the outside of each bearing where it lines up with the flat surface of the case half, where the other case half seals against it. This way you know how the bearing needs to be rotated to line up with the dowel pin. Once this is done, go ahead and put the bearings on the crank. For assembly lube I use STP Oil Treatment, it's very thick and stays in place nicely.

Coat the insides and sides of the main bearings with it and also the main journals on the crank. The #1, 3, and 4 bearings all slide onto the crank. Make sure you orient them properly so the dowel pin holes are on the correct side. The #2 bearing is the split bearing. Put the dowel pins into the case halves and put the #2 bearing halves into the case halves. Make sure they are lined up properly, it is possible to get them a little crooked. In fact, what I like to do with the #2 bearing is to put it into the case by itself and then put the two case halves together. Snug down the main case stud nuts. You can then look through the cylinder openings and see if the halves of the #2 bearing line up with each other. If they don't, gently tap on them with a rubber mallet and a plastic or wooden rod as needed till their edges are perfectly aligned. Once they are aligned, take the case halves back apart being careful not to disturb the #2 bearings. So now the #2 bearing halves are properly registered in the case, and you have the #'s 1, 3, and 4 bearings lubed up and on the crank. Now its time to set the crank into the first case halve, the one with the dowel pins. I put the index finger of each hand into the hole of each end of the crank and lift it like that. Set the crank down gently in position. Now those lines you scribed on the bearings come in handy. Gently rotate each bearing shell so that the scribe line lines up with the case sealing surface, the bearing should seat into the dowel pin. You may have to go back and forth a little with the 3 bearings till they are all seated, because one not being seated can prevent the others from dropping into place. When you think you have them all located on their dowel pins, take a look and see that the outside of each bearing is seated on the saddle on the case, there shouldn't be any gap in there, if there is then keep messing with the bearings till they are all seated properly. At this point go ahead and give the crank a gently turn, it should spin freely. Go ahead and carefully lower the other case half onto the assembly. The two case halves should meet on their sealing surfaces very easily, if they won't go together the crank bearings are not seated properly and you need to figure out what the problem is. If it does go together like it should, go ahead and give the crank a very gentle spin, it should spin as easily as before. If that checks out go ahead and put on the big case nuts and snug them down to a couple ft-lbs, then check crank rotation again. Keep tightening and checking the rotation till you get the case torques down to spec. At this point, the crank should spin as freely as it did when you just had it sitting in one case half. If it doesn't then you pinched a bearing or have some other problem.
Once the crank checks out I repeat this basic procedure with the cam, and make sure it spins freely too when the case is torques down. When you check the cam you can go ahead and leave the crank in, it shouldn't matter. With the cam though you need to also torque up the small case nuts.

Now that your main bearings have passed the test, you can go ahead and assemble the crank. The #3 bearing goes on first, again make sure you have it oriented correctly with respect to the case dowel pin. Next are the cam gear, spacer (I use a Racer Spacer solid spacer), distributor gear, and finally the C clip. The cam gear and distributor gear are interference fit, so the only practical way of getting them on it to heat the living daylights out of them to expand them enough so they will drop right on.

Set your cam and distributor gears in a stack on your stove, a hot plate, or what ever. For mine, it took about medium heat on my stove to heat them enough so they would fall right on. You don't want to heat them more than necessary though because you may mess up the temper of the cam gear, so start on a lower heat setting and keep testing if it will go on or not and increase the heat a little at a time till it falls on. Make sure when you drop the cam gear onto the journal that the two timing dots are facing the pulley end, you will need to reference those when you put in your cam.


Here it is assembled and sitting in the case



If you want, you can check endplay at this point too. For me it was easier to do with just one case half because my flywheel is wedgemated to the crank and a major PITA to get off if the engine is assembled. I basically just set the other case half on there when I took this measurement.


Now that the gears are all on the crank, I like to test everything out together. Set the crank in the case with the bearings as before and rotate it so the two marks on the cam gear are maybe 15 degrees clockwise of straight up. Now take the cam and put it so the tooth with the mark on it goes between the two marks on the crank gear, then, keeping the teeth meshes, rotate the cam down into the case. now rotate the cam and crank and verify that the tooth on the cam gear is between the two marks on the crank gear. Put the second case half on and torque it down. Check that the crank and cam spin freely together. Now I like to take it apart and add the distributor drive to the assembly and check it again. Leave the cam and crank in and put the distributor drive in, with the two washers under it. Get it indexed properly. Stick a distributor in and snug it down to keep the distributor drive from falling out if you have the engine tilted. Now put the other case half on, torque it down, and make sure everything spins freely. I had some burs on my distributor drive that I had to take down that were causing it to catch a little when rotating. Because I had tested everything by itself up to that point, I knew exactly where the problem was. It may seem like a lot of extra work doing so many mock ups, but in the end you know everything is perfect, and if there is a problem along the way it is easier to pinpoint.

Stay tuned, more to come. Almost ready to finish up the short block

Where do I buy those tools? I wanna build a motor also. Except, I'm not gonna "slap it together" like when i was younger. And where do I get vice pads?

Most of my tools I ordered from McMaster-Carr. My soft jaws for my vice are just aluminum angle stock that I cut to length.