Tuesday, May 3, 2016

Easy Cam Cover Fixture

Here's a little something for those of you who do some of your own engine work. 

Years ago, when I first saw the Jim's fixture for supporting a cone style cam cover, my thought ran something like this, "Okay, I see the point, but I sure can't see spending that much for something I've gotten by without for all these years."  Nevertheless, the idea is a good one.  Support the cam cover in such a way that the outside surface won't be at risk of being marred, along with providing a stable base for installing bushings and pinning them to prevent possible rotation.  But face it, the portion of the cover that is filled by the timer cover is horizontal to the gasket surface, so drilling for the pins can be accomplished on a drill press without too much trouble.  Just a matter of protecting the finish on the cover.  The pinion bushing is a little more dicey due to being off to the side, but one can get by.

However, over the course of time one of my colleagues mentioned that he had one of the Jim"s fixtures and was impressed with how much easier it made the job.  Of course his input didn't suddenly transform me from being a cheapskate, so rather than ponying up the money for the Jim's fixture, I made my own, as seen below. 

You may notice that mine is a little simpler to fabricate than the Jim"s tool because it supports the cover from the deepest part of the timer cavity rather than the "points cover" gasket surface.  This makes the diameter of the pipe of little importance as long as it will fit inside the cover.  And my colleague was absolutely correct about how handy such a fixture is. 

In fact, I was impressed enough that I decided a similar fixture would be in order for generator style cam covers, especially given the number of early motors that seem to find their way to me.  A fixture for a generator cover, however is a little less straight forward, though actually easier to build.  At first glance the obvious problem is that there is no flat surface on the outside of a generator cam cover to work from.  However, there are points on the outside of the cover that will provide a "level" surface; 12 of them as a matter of fact. 

That's right, the mounting screw holes.  "But they are countersunk," you say. Not really a problem.  It just so happens that the top of a 1/4" acorn nut has just about the right shape to fit the countersink taper which the covers have for each mounting screw. 

Having fabricated one of these for doing Big Twin cam covers some time ago, I found it even more essential than the one for cone style cover bushings.  So last week when I found myself in need of one for a 45" cover, I snapped a few pictures of the finished fixture. 

I used 1/4 inch aluminum plate for the base, since I had some.  You probably wouldn't want to use too much thinner material because you will probably want to use countersunk screws so the bottom remains flat.  2" long hardware store screws (more likely to be available with threads the whole length) provide enough depth for clearance on the rather thick 45" cover.  Shorter screws would be in order for a Big Twin fixture.  The crude drawing is a must to aid in placing the cover onto the fixture without trying each combination of holes every time.  Well, ...I guess its not a must that the drawing be crude; just that there be a drawing.  I suppose if you wanted to use up a bunch of extra material you could make the support plate the full size of the cover and add more screws so the orientaion would become obvious, but I think I may have already mentioned that I am a cheapskate.
There you go.  An easy way to not only protect the finish on your cam cover, but also to hold it level for bushing replacement and drilling for those pesky pins.

Tuesday, April 26, 2016

Murderer Update

As per standard operating procedure around here, I am lagging far behind in blogging, by way of a failed attempt at keeping up with demand on the porting and engine rebuilding side of things. Because of this, the egregious stories of this nation spiraling into paganism keep piling up faster that I could ever find time to comment on them. But sometimes you just have to make the time to speak out.

You may have noticed, in recent times I have confined my rants to the subject of the ongoing government sanctioned murder of babies. There is much else currently taking place which rankles, and which are also a fairly obvious signs of the Almighty's judgment on the USA. Though they are equally contrary to the laws of God, it seemed reasonable to limit my commentary to that issue which so clearly divides a moral from an immoral people. In other words, if you can't find it within yourself to come down on the side of life rather than the side of murder, well, ...let's just say that there isn't much in this world that a sane man would leave to your judgment.

But as I said, the headlines just keep piling up on the murder/no murder issue. And I might add, if this is the first you've read of any of this, it might be time to remove your head from the sand: God is watching and it seems that I read somewhere that being willingly ignorant may not be the strongest defense in the long run. For example, since the beginning of April, these headlines have appeared:

April 5 - "Appearance of Impropriety: Judge’s Husband Has Apparent Link to Planned Parenthood" - (source - Operation Rescue) "Columbia, MO - Federal Court Judge Nanette Laughrey, who is blocking the Missouri Department of Health and Senior Services from revoking the abortion facility license of the Columbia Planned Parenthood facility, is being called on to recuse from the controversial case after pro-life activists photographed her husband, lobbyist Chris Kelly, entering that same facility on March 10, 2016."  Well, maybe the husband is a lobbyist for Planned Parenthood, or maybe he just has a "knocked up" floozy on the side that is in need of the murder for hire services of Planned Parenthood. Either way it would seem to be a clear cut case of conflict of interest. But of course corruption only gets called by name when it sees the light of day, and people are found to actually care.


April 6 - "Yesterday, the California Department of Justice, led by Planned Parenthood-backed Attorney General Kamala Harris, raided my (David Daleiden) home and seized my laptop, my personal files, and all of CMP's video footage, including unreleased material, of Planned Parenthood's criminal trade in baby body parts." (source - David Daleiden)

Mr. Daleiden is the gentleman who has gone undercover to expose the illegal sale of murdered baby organs. I have linked to a number of his undercover videos on this blog. Attorney General Harris has reportedly received tens of thousands of dollars from Planned Parenthood, which cannot help but show her to be their bought and paid for attack dog. It would be tough to imagine that a taxpayer supported "murder for hire" business such as Planned Parenthood would think twice about bribing their way to revenge.

April 7 - "CA AG's Office Ransacks Daleiden's Apartment to Defend Campaign Contributor Planned Parenthood" (source - Operation Rescue) Here we also learned that there is evidence that supports accusations that Harris' investigation was politically retaliation, which at its core is an attack on the right to free speech.

April 13 - "How Harvesting Organs from a Dead Abortion Patient Thwarted Justice" (source - Operation Rescue) This piece tells the tragic story of the death of a Cleveland woman while having an abortion performed. The tragedy continued when the plea and even written request by the father (and grandfather) of the victims (plural!) that an autopsy be performed to determine the cause of death, was ignored. Instead, because of an organ donation box had been checked two years earlier when renewing her drivers license, the woman’s body was quickly harvested of parts and her family will never know what kind of malpractice may have lead to her death. That the woman’s father will never have the joy of bouncing his grandchild on his knee can only add to his seemingly unbearable pain.

April 15 - "Collusion Between Houston DA’s Office and Planned Parenthood Alleged in Daleiden’s Motions to Quash Texas Indictments" (source - Operation Rescue) This story which I have mentioned before, revolves around how a Houston Texas Grand Jury which was called to decide whether to indict a Planned Parenthood affiliate for the illegal sale of murdered baby remains. Instead, under leadership of District Attorney Devon Anderson the grand jury indicted the witness to the crime, that is David Daleiden, for allegedly breaking the law by filming the criminals as they unwittingly confessed. In an ongoing pattern of corruption, it was revealed that Josh Schaffer, attorney for Planned Parenthood bragged that he had persuaded DA Anderson to turn the grand jury against Daleiden.

April 18 - "Planned Parenthood’s attacks on pro-life activists make Al Capone look like an amateur" (source - Troy Newman of Operation Rescue) Some interesting facts and numbers here. California Attorney General Kamala Harris, the woman behind the raid on journalist David Daleiden’s home, is running to be a United States Senator from the state of California. Planned Parenthood has donated over $81,000 dollars to her campaign since 2010. Planned Parenthood in turn receives $4.8 BILLION of your taxpayer dollars to aid them in their quest to murder babies. Seriously, with that kind money being taken out of the pockets of hard working Americans and lining the pockets of Planned Parenthood, one has to wonder if their sideline of selling the body parts of murdered babies is based more on depravity than on greed.

April 19 - "The House of Representatives Select Investigative Panel on Infant Lives released a new set of documents this evening from their investigation that PROVES Planned Parenthood profited from the sale of aborted baby parts." (source - David Daleiden) Nothing really new here except that maybe, just possibly maybe, one branch of our government will wake up to the fact that for the past 9 months Planned Parenthood has been lying when they claim the receive no financial benefit from selling little baby hearts, brains, and lungs. Think anyone is paying attention? Think anyone cares?

April 21 - "Barack Obama’s Department of Health and Human Services just sent a letter to all 50 states, threatening that there will be consequences if they cut taxpayer funding to the nation’s largest abortion provider!" (source - Troy Newman of Operation Rescue) This is hardly surprising from the President, who while a Senator, voted against making it illegal to murder a baby when he is half way born. Let’s see now, how does that "partial birth abortion" that President Obama supports work? The whole body of the live baby with the exception of the head is delivered, and then the baby is stabbed to death. Then the baby’s head is delivered, but by now dead. I have to say though, its a bit surprising that the method was not reversed; after all, weren’t they afraid if the baby had its hands out of the womb they might try to defend themselves? Also of note was that Planned Parenthood has adopted the tactic of suing Mr. Newman personally, obviously with the intent of destroying him financially by forcing to defend himself, thereby silencing him. The beauty of that plan (from the devil’s viewpoint) is that Planned Parenthood doesn’t even have to win to achieve their ends.

April 21 - "Operation Rescue complaint ignored while Alexander remains free to break the law." "Forestville, MD - An abortionist who is currently barred from conducting surgical abortions at an unlicensed facility has been caught red-handed conducting late-term Dilation and Evacuation abortions late at night in an apparent attempt to avoid detection." This one concerns Harold O. Alexander who plies his trade of baby murder in the state of Maryland. Despite a history of illegal abortion activity and current pending charges against him, the Maryland Department of Health and Mental Hygiene doesn’t see fit to spend their time or resources to put an immediate stop to Alexander’s illegal slaughter of babies. The pending charges against Alexander date back nearly a year, but hey ...what’s the hurry? Its not THEIR lives that are at stake.

April 23 - "In the Market for Fetal Body Parts, a Baby’s Brain Sells for $3,340" (source - The Daily Signal) The U.S. House Select Panel on Infant Lives is in the process of investigating the sale of fetal tissue from aborted babies and now have access to the menu. On the retail side of things, researchers (the end user) can expect to pay the dealer (fetal tissue procurement companies such as Stem Express) $3,340 for a baby’s brain, $595 for a "baby skull matched to upper and lower limbs," and $890 for "upper and lower limbs with hands and feet." Of course the Planned Parenthood affiliates sell to the dealers at significantly less than that amount, just as a manufacturer in the motorcycle parts business sells to the dealer at a reduced price so that he too can show a profit. Of course the middleman in this case also provides some cover and plausible deniability for the ghouls at Planned Parenthood. Don’t feel that they are getting the short end of the stick though; remember, the money they receive for the baby body parts is almost all gravy (if I can use that term without gagging). The dead babies would need to be disposed of anyway, so in some ways its similar to me saving scrap metal to sell rather than tossing it in the dumpster (well, similar except for the murder part, of course). BTW, the definition of a ghoul is "an evil spirit or phantom, especially one supposed to rob graves and feed on dead bodies." If the people who work at Planned Parenthood don’t fit that definition, no one does.

Well, there you go. As each of these stories came to my attention I was outraged. I could have spent time on each of the above dates expressing my outrage and calling for national repentance of this appalling savagery that should never be tolerated, let alone subsidized by a civilized society. Your tax dollars at work. My tax dollars at work. This nation deserves any judgment that God may bring upon it.

One last word for any woman who has paid to have her baby murdered, and even for those hired assassins at Planned Parenthood: There is forgiveness for those who turn from their sin. Holy scripture tells of a number of murderers who found grace, but they did not find it without repentance.

Saturday, February 27, 2016

By the Numbers, Part 2

Well, as proposed, in light of the first post in this series in which we looked at minimum Cross Sectional Areas of your intake port and how they can affect flow potential. One thing that we saw was that preferably we would like to see the minimum CSA to be the throat (Also Known As venturi, AKA neck, AKA choke) just under the valve seat. I might add two points in regards to that assertion. One is that this may only be applicable to Harleys and not to other heads with significantly longer intake tracts. The other point is that I am not advocating larger than needed port CSA's, only that one should take into consideration those parts of the port that are actually a limiting factor to flow. We saw that the minimum CSA is in at the throat under the seat with the Evo/ Twin Cam intake port, but only at the points where the port is round and easy to measure. But what about where that port is no longer round (which is most of it). Just a quick visual confirms that the real minimum CSA is probably not at either the round port opening or the throat under the seat.

 Twin Cam

The first obvious thing you see looking into the port from the manifold end, is a "hump" in the floor. And right here let's take a moment to thank the Lord that we are dealing with an overhead valve motor right now so that there is no confusion as to which part of the port is the floor (hint - if you were short enough you could walk on it). Just imagine the confusion if we were forced to look at a Flathead port like we did to explain the concept of curtain area in our last post. Even I'm not sure which would properly be termed the floor and roof on a Flathead. Would one have to turn the Flathead cylinder upside down in order to keep the "short side" radius as the floor and the " long side" as the roof? Or do you leave the Flathead cylinder in the orientation that God created it in, and rename the short side the roof and the long side the floor? The potential for confusion is immense. Whew. Good thing were talking OHV right now! By the way, the short side radius is just what the words mean. The length from the port opening to the valve will be considerably shorter on the floor than it is on the roof (again from an OHV point of view).

As I said, the hump in the floor of the port is pretty obvious and changes the port shape from round to a sort of "D" shape (tipped 90 degrees counter clockwise). Obvious as it is in an Evo, the hump is even more pronounced in a Twin Cam. Though it's going to be very difficult to measure the Cross Sectional Area once we get into the port where it is no longer round, we can certainly get some sense of it from a few measurements.

I keep a suitably modified inside caliper on my porting bench. You may notice from the picture that there I have two sets of notches (filled with a bit of red paint for clarity) as reference points. These arbitrary reference points are a handy way to locate a fixed point for measuring since the port walls are tapered. By putting the caliper into the port so that the matching reference points align with the face of the port opening, one can easily take multiple measurements at a set depth. My calipers are marked at .750" and 1.500".

On this particular Evo head, the port opening measures a nominal 1.610" (it not quite round). But at a depth of .750" in from the port opening it measures 1.745" side to side and 1.375" top to bottom. So the port has gotten .135" wider, but at the same time it has become .235" shorter. That makes it pretty self evident that is a smaller Cross Sectional Area than at the port opening. When we make the same measurements on the Twin Cam head, the results are no better. The port opening of this particular head measures 1.650", but 3/4 of an inch in, the measurements are 1.845" side to side and 1.235" top to bottom. The question you must ask is this: did the increase in the width of the port make up for the decrease in height?


Remember what I mentioned about the preferable place for the minimum Cross Sectional Area being the throat under the valve seat? Since it is quite obvious that is not the case with these heads in their stock configuration, we can be pretty sure that to get the full flow potential from these heads, something needs to be done to enlarge this "pinch point" so that the minimum Cross Sectional Area is in fact under the seat where it belongs. 

Big Hint: don't cut down the "hump" to get the port closer to round. The hump is there for a good reason - and that reason is twofold, though related and codependent. The primary reason is form over function. Fatbob tanks have been a signature feature of Big Twin Harleys since the 1930s, and in order to keep the air cleaner from interfering with those tanks, the ports (both Evo and Twin Cam) had to be kept as low on the heads as possible. A port entry with a higher angle of approach to the valve would have made far more sense from a performance standpoint, but the factory knows the audience they are playing to. But in an admirable attempt to have their cake and eat it too, the Motor Company added the "hump" after the low entry point in order to help gently turn the air around that short side radius.

Don't get me wrong though. Just because the minimum Cross Sectional Area is in the wrong place, it doesn't mean the significant flow gains cannot be realized by porting without addressing that fact. In other words, if you (or the person porting your heads) never noticed this point of restriction, it doesn't mean the heads can't have considerably better than stock flow, it just means the flow will not reach the optimum. Now I should mention that there are probably some practitioners of the porting arts out there who will plea that some "pinch' of the port CSA is a good thing to have at the 'hump" and that it helps turn the air. I am not sure that I am smart enough to agree or disagree with that theory, but to attempt to prove it, I think one would have to be able to accurately measure the CSA of that pinch point and then by varying its size, empirically show how much constriction yields the best results. Whatever method you use to get there, you will know that you arrived at a near optimum port flow when it matches the CSA of the throat under the seat multiplied by 133.

Now keep in mind that this "secondary" choke point in the vicinity of the hump is pretty difficult to measure (as previously mentioned) due to its irregular shape. But adding to that irregularity is the valve guide boss. That right, by the time you are 1/2" into the port, the cross sectional area is not only being reduced on the bottom by the hump, but on the top by the valve guide boss. By now that cross section looks more like the drawing below:

Anyone want to take a stab at giving an accurate Cross Sectional Area for that shape? 
(it is possible, but quite time consuming) 

Okay, once you have the port flowing close to that magic 133 x the minimum CSA of the throat, you will know that you have the rest of the port to the point where it is no longer the limiting factor. And since this post is intended to informational in nature rather than a full blown "how to" we will leave the "hump" section of the port.

Keeping in mind the ideal of the minimum CSA being at the throat just beneath the valve seat, what then happens when you add a larger intake valve? Well, if you don't open up the diameter of the throat, then the minimum CSA stays the same and thus the theoretical maximum air flow remains the same. The larger valve has not helped at all except that it gives you more room to turn the air more gradually if you shape the seat correctly, but that only gets you closer to the maximum possible flow through that same minimum CSA.

But here we probably need to add another number to the mix. That is the relationship between the valve diameter and that of the throat below the seat. This is expressed as a percentage of the throat diameter verses the valve diameter. In other words if you have a stock Evo/Twin Cam intake valve that measures 1.843" with a throat of 1.625", the percentage would be 88.2% (rounded off). Today it is commonly accepted in the porting world that the range for this percentage is from 88 to 91% for best performance, though early Superflow literature suggested 85%. The exact number within that range may be tailored by application, with the lower RPM engines with low lift cams benefiting from the lower percentages. 90% is generally a good safe figure to use; 91% can be too big; while 92% is definitely too large and will likely hurt performance (though not necessarily flow). With that in mind, what happens when you put in a 1.900" intake valve (as is most common when porting Evo and Twin Cam heads)? If you open up the throat to 90% of that 1.900" valve, it will be 1.710". That has obviously moved our minimum CSA from the throat to the port opening (or to the "hump" as it may be). In other words, the 90% valve throat has a flow potential of 305 cfm, but your port opening will only handle 275.

Again, I would like to stress that just because your port opening is only of stock size, that does not mean that a 1.900" intake valve will not help your flow. We are dealing with theoretical maximum potential here, not hard and fast rules on how your heads must be configured to improve performance.

One thing that I might mention here relates back to part one of this series, having to do with curtain area. If you were to put 1.900" intake valves in your heads, keeping the stock port opening diameter the lift required for the curtain area to equal your minimum CSA will only go up an insignificant amount (.002") because that minimum CSA has not changed much, it is merely located in a different place in the intake tract.

since we are looking for the lift at which CSA equals the curtain area, insert the
CSA figure in the formula in place of Curtain Area
Remember the minimum CSA with the stock valve was 1.999 (throat CSA minus stem CSA). With the larger valve and matching larger throat under the seat, the minimum CSA is now at the port opening which is 2.074 square inches. If however, the port opening was not the place of minimum CSA, and the throat was, then the lift required for the curtain area to equal that point would be .372" (that is arrived by calculating the CSA of the throat [2.297], subtracting the CSA of the stem [.075], and then dividing that by the product of 3.1416 multiplied by the 1.900 valve diameter [5.969] ).

To get some perspective of how this lift = curtain area point changes when taken to an even more high performance application, let's consider the Screamin' Eagle 2.175" intake valve used in their "Hurricane" heads. IF they used a 90% throat, it would work out to 1.958" I.D. or a throat CSA of 2.935 square inches when corrected for the valve stem diameter. Plugging that into our formula we find that the valve curtain area will not equal the throat area until a lift of .430". That might change your perspective a bit on what might be considered low lift flow.

Just one more warning at this point. This calculated curtain area does not give you the lift needed for a given valve size or port size. It only gives you the lift at which the curtain area is no longer a primary limiting factor to flow. It is not the lift at which the your port will reach maximum flow (unfortunately not even close) but it does give you some insight as to how important the valve size and seat shape is at lifts below the point where the curtain area equals the minimum CSA.

At the end of part 1 I said that I would eventually get to how much air flow your engine really wants. Looks as though that means there will be a part 3.

Tuesday, February 9, 2016

False Scales

Unequal weights are an abomination to the LORD, and false scales are not good. Proverbs 20:23

Woe to those who call evil good and good evil, who put darkness for light and light for darkness, who put bitter for sweet and sweet for bitter!  Isaiah 5:20

It is a fearful thing to fall into the hands of the living God. Hebrews 10:31

These are the first three scriptures that came to mind when the story broke of David Daleiden and Sandra Merritt being indicted for shining light on the despicable and illegal practices of Planned Parenthood in selling dead baby parts.  Hard to believe as it may be, Houston Texas District Attorney Devon Anderson had the audacity to turn the tables on the investigative reporters during a Grand Jury procedure which was supposed to indict Planned Infanticide Parenthood using Operation Rescue video sting footage as proof of illegal practices.  Instead, he indicted Daleiden and Merritt for going undercover and for attempting to purchase baby parts!  Oh yes.  Of course they were trying to buy baby parts; that's why they published all the undercover videos - because they were really trying to enter the black market in murdered baby parts. [sarcasm]  If you follow this blog regularly, you know I have linked to more than one of these videos.

This should not have come as too much of a shock since D.A. Anderson previously saw to it that Houston murderer Douglas Karpen did not have to stand trial for slashing the throats of some and twisting the heads of other babies born alive during late term abortions.

Unequal weights of course refers to type of balance scale that uses a "known standard" weight on one side, to "measure" the item on the other.  An unequal weight would be a "standard" that did not really weigh what it was claimed to weigh: a common way to cheat in commerce.  Indicting the Operation Rescue operatives for "attempting to buy" baby parts, while at the same time refusing to charge Planned Parenthood for "attempting to sell" the same is a tolerable good example of this practice.

This charge against Operation Rescue and the parallel refusal to indict Planned Parenthood also serves as a prime example of calling evil good and good evil, though I must admit that verse comes to mind all too frequently when I observe modern day culture.

As for Hebrews 10:31, it is quite self explanatory, both as a cause and a warning.  A cause in that it is a lack of the fear of God which lies at the root of such abominations.  A warning in that, barring repentance, things will not go well for the Planned Parenthood people and their enablers.

Saturday, January 30, 2016

By the Numbers, Part One

I am not a "numbers guy" the way some are. I don't find joy in numbers just for the sake of numbers. One reason might be that I generally don't remember them especially well, though there are a few exceptions; mainly those numbers burned into my brain from repetition, repetition, repetition. For instance I have not yet, and may never forget my social security number since that dark night on the bus taking a load of new recruits from the airport in San Antonio to Lackland Air Force Base for Basic Training. A very intimidating uniformed fellow informed us in no uncertain terms that "YOU WILL HAVE YOUR SOCIAL SECURITY NUMBER MEMORIZED BY THE TIME YOU GET TO THE BASE!" Possible consequences for failure were left to our imaginations, but for an 18 year old fresh off the farm ..., well let's just say I didn't spend much of that ride gazing out the window.

Some of the other numbers that seem to be forever stuck in my brain are strictly due to much use. Its been many years since I have had to look up the center to center rod length for a pre Twin Cam big twin. 7.43875" for the late and 7.46875" for the early. I'm pretty sure that comes from balancing well over 100 sets of flywheels (last time I counted) over the last 35 years.

But other than that, numbers don't hold any special favor in my consciousness. What numbers can do for me, on the other hand ..., that I can get excited about. That's why I just had to share a couple of formulas that I recently ran across while searching some of my reference material. The particular reference book I was perusing was "Engine Airflow" by Harold Bettes. He's a smart guy, so I've read through the book more than once. By the way, I titled this post before noticing Mr. Bettes has a like named chapter in his book, but I didn't get it from him - I would assume that I inadvertently stole it from somewhere else.

One of the first formulas that caught my attention on this particular day concerns determining curtain area of a valve. If you're not familiar with the term, picture a valve lifted off its seat, with a "curtain" hanging around the perimeter of the valve  to the seat. Okay, maybe it will help if you begin by picturing this on a Flathead motor where the valve head faces up so that you don't have to concern yourself with how a curtain could defeat gravity and "hang" from a valve "up" to its seat. Are you picturing it now? Good. The area of that "curtain" has a good bit to do with flow potential. The simplified formula for computing this is the following:

Before we get into applying this formula, let's consider something else. Cross Sectional Area (or CSA). When dealing with heads, the CSA we often are concerned with is the Minimum Cross Sectional Area. Now, it is self evident that there is limit to the volume of air that can pass through a given size hole at a given pressure. There is one place in every intake tract that is smaller that the rest of the system, and the point with the smallest cross sectional area can be the limiting factor in air flow (in the real world it will take a well ported head for this to be true). That smallest point in the intake tract, or minimum cross sectional area is only easy to measure where the intake tract is round, but for my purposes right now, that is okay because the Harley ports are round (or at least they were meant to be) at the port opening. Another point where the intake tract is round and thus easy to measure, is the "choke" or "venturi" just under the valve seat.

So, if we were to take, say for example an 80" Evo... Why an 80" Evo, you ask? Well, it is clearly the direct forerunner of the Twin Cam. The ports are quite similar, and in fact they share the same port opening diameter and even the same intake valve (at least to 2004). That port opening diameter is 1.625".

Happily the choke I.D. (under the valve) also is 1.625". I say happily because that is the one place in the intake tract that you absolutely must have a "choke" point so it is the obvious place for the minimum CSA. If you are wondering why Harley left a second minimum CSA at the port opening, they didn't, but we'll get back to that in a moment. First lets convert that diameter to Cross Sectional Area. The formula is this:

That gives us a CSA of 2.074 square inches for a 1.625 diameter opening. In other words the CSA for the port opening is 2.074". But not quite for the "choke" under the seat, because that also happens to have a valve stem protruding through the center of it. Once we calculate the CSA of that stem (which generally measures .310" diameter) and subtract it, we see that our choke just under the seat of 1.999 square inches is indeed the minimum CSA.

Now back to that curtain area formula. One of the cool things about algebra is that it allows you to turn formulas around to suit your needs. In this case, computing the curtain area for your intake valve at full lift might be handy, but wouldn't it be even more interesting to see what lift it would take so we can be sure the valve curtain area is not the limiting factor. In other words, what valve lift would it require to equal the minimum CSA of the port. Turning that curtain area formula around would look like this:

If we take our previously calculated minimum CSA of 1.999 (which is our desired curtain area) and divide it by the product of pi (3.1416) multiplied by the valve diameter (1.843), we come up with .345" valve lift. So, you can see that the Harley engineers did their homework in providing a stock cam with more than enough lift (.472") to provide a curtain area theoretically large enough that it does not become a limiting factor. If one were to take things a step further, Bettes' book also includes a formula for computing the minimum CSA required for a given Cubic Feet per Minute (CFM) of air flow measured at a 28" test pressure. That formula is:

Or, once again to turn that formula around for my own purposes:

If we were to plug our minimum CSA into that formula we would find that theoretically, our stock Evo (or Twin Cam) heads with stock valves and valve seats, together with a stock cam, should have the potential to flow nearly 292 CFM (1.999 x 146) @ 28" test pressure. Wow.

But back in the real world... That theoretical flow potential of 146 CFM per square inch of Cross Sectional Area is a figure that has been calculated and confirmed by a number of people way smarter than me over the years, and while correct, it admittedly does not take into account any friction losses, and perhaps most importantly it does not account for loss of flow due to expansion which must happen when the air flows out of the port and into the cylinder. According to Patrick Hale's "Engine Pro- The Book" this figure when adjusted to take these other factors into account, along with "benchmark" results (as of 2004) reduces the target to a more reasonable 133 CFM per square inch. Still, that leaves your OEM head with a potential of 265 CFM (1.999 x 133).

But if we were taking a trip back to the real world when we reduced the flow potential to 133 CFM per square inch, then its time to get our heads out of the clouds, because even if the clouds are in the real world, most of us don't ride our Harleys there. So keep in mind that it will take a very good porting job to take full advantage of the potential flow through that minimum Cross Sectional Area.

On the next installment of this multi-post series, I'll try to take a look at a few things such as why the minimum cross section we just spent our time calculating may not be where the actual minimum CSA is located, what happens when we add porting and bigger valves, and eventually on to how much air flow your engine really wants.

Wednesday, December 30, 2015

New Year, New Man

 Therefore if any man be in Christ, he is a new creature: old things are passed away; behold, all things are become new. (2 Corinthians 5:17)

Since we are on the verge of the new year 2016, and 2015 is about to pass away, this seemed like an appropriate passage for New Year's Eve. This verse also happens to be a favorite of mine. One reason is because it is one of those verses that has shown itself to be so helpful. In a world plagued by false conversions and false professions of faith, it is one of those foundational verses which help us discern not only the truth of other people's faith, but even more importantly, our own.

Of course you might ask, what exactly does it mean for a person to be "in Christ" as the verse phrases it. Perhaps the best answer is found in John chapter 15. Jesus, speaking to his disciples, said this.

I am the true vine, and my Father is the husbandman. Every branch in me that beareth not fruit he taketh away: and every branch that beareth fruit, he purgeth it, that it may bring forth more fruit. Now ye are clean through the word which I have spoken unto you. Abide in me, and I in you. As the branch cannot bear fruit of itself, except it abide in the vine; no more can ye, except ye abide in me. I am the vine, ye are the branches: He that abideth in me, and I in him, the same bringeth forth much fruit: for without me ye can do nothing. (John 15:1-5) 

This metaphor compares us to branches on a vine that is Jesus Christ. The branches depend upon the vine for sustenance, just as a Christian depends on God's word. The branches of a vine are the means by which the vine bears its fruit, just as the Christian is Jesus' chosen way of building his kingdom. In other words, the person who is abiding in the vine, or in Christ, is the genuine believer.

Of course 2 Corinthians 5:17 is not the only place we find that speaks of one who is "in Christ" as being a new creature.

In Ephesians 4 we read this:

But ye have not so learned Christ; If so be that ye have heard him, and have been taught by him, as the truth is in Jesus: That ye put off concerning your former manner of life the old man, which is corrupt according to the deceitful lusts; And be renewed in the spirit of your mind; And that ye put on the new man, which after God is created in righteousness and true holiness. (Ephesians 4:20-24)

Now, since the Christian is commanded to put off the old man and put on the new, it may lead one to believe that this becoming a new creature, is an act of your own will. That is true at least on one level, for from our point of view it is a matter of deciding to do, and then to do it. However, the other side of that coin can be found in Paul's letter to the Philippians where he says this: For it is God which worketh in you both to will and to do of his good pleasure. (Philippians 2:13)

In other words, it is God who works in you to change your will so that you want to do what pleases him. God doesn't force you, the Christian, to do things you don't want to, but in his grace and mercy he gently and imperceptibly changes your will, so that it conforms to his will. The results of this change in your will, which we might call the new creature, is found in numerous places in scripture, among them Ephesians 4 where we just left off a moment ago.

Wherefore putting away lying, speak every man truth with his neighbour: for we are members one of another. Be ye angry, and sin not: let not the sun go down upon your wrath: Neither give place to the devil. Let him that stole steal no more: but rather let him labour, working with his hands the thing which is good, that he may have to give to him that needeth. Let no corrupt communication proceed out of your mouth, but that which is good to the use of edifying, that it may minister grace unto the hearers. And grieve not the holy Spirit of God, whereby ye are sealed unto the day of redemption. Let all bitterness, and wrath, and anger, and clamour, and evil speaking, be put away from you, with all malice: And be ye kind one to another, tenderhearted, forgiving one another, even as God for Christ's sake hath forgiven you.
(Ephesians 4:25-32)

The bottom line is that for the true Christian, at some point in their life there will have been a change. They will have become a new creature. Their old way of life will have passed away. Everything will have become new including their desires. They will desire to please God rather than fulfill the lusts of the flesh. If you have never experienced such a change and the concept is foreign to you, it should be a matter of grave concern. In Paul's letter to the church of Corinth he urges them: Examine yourselves, whether ye be in the faith; prove your own selves. Know ye not your own selves, how that Jesus Christ is in you, except ye be reprobates? (2 Corinthians 13:5)

We began with this text: "Therefore if any man be in Christ, he is a new creature: old things are passed away; behold, all things are become new."

Have you examined yourself in light of this scripture?

Thursday, December 24, 2015

Doug Wilson's Night Before Christmas

Couldn't help but share this poem by Doug Wilson.  If you choose to pass it along, please be sure to give proper credit to the author.

‘Twas the night before Christmas and all through the land,

We still mark the birth of the One who is banned

From public discussion or public display.

"Get rid of the Christ child–but still keep the day!"

So public school children must practice with stealth

Those carols which threaten our strange commonwealth,

And now and again someone’e runaway creche

Will abruptly appear in some government place,

Right out in the open where children can view

This threat to the folks at the ACLU.

So drink to the health of our once happy nation,

And deck all the halls with strange litigation.

Then eat all you want to, drink rum by the quart

But don’t say that name, or you’ll wind up in court.

Pretend that this holiday just always was.

Don’t ask whence it came like a smart child does.

Just talk about Rudolph or Santa’s small elves,

Or sing little ditties of days bunched in twelves.

Now this is all right because (please get this straight)

There’s no separation of North Pole and state.

So sing all you want of this sort of stuff

In the public arena, folks can’t get enough.

If you do sing the carols, then please, just be careful.

Look over your shoulder, keep watch and be prayerful.

Edit those carols, avoid our law’s curses,

(You’ll have to leave out quite a few of the verses.)

So you won’t get the secular humanists riled

With songs about sinners and God reconciled.

"Be near me Lord Jesus, I ask Thee to stay,"

Angers the People for the Humanist Way.

But if you believe the time is now ripe

To stand up for Christmas, don’t sit there and gripe.

The secular Scrooges and Grinches will hear

If you say, "Merry Christmas," with all the right cheer.

It’s time to be counted for what’s good and right,

To all, Merry Christmas! To all, a good night!