Cam-a-palooza

Top row Big Twin, Center WL, Bottom WR

About a week ago, I received an anxiously awaited package via my friendly local UPS driver. It was the return shipment of three sets of Flathead cams which I had sent off to Mr. Jim Leineweber for regrinding. I believe its a little unusual for a small shop like mine to be dealing with three Flathead engines at the same time (though to be honest, the Big Twin of the bunch is now officially on hold due to the owner putting his new found Knuck engine in line ahead of his Flattie)

The Big Twin cams have been ground to .420" lift and +10 degrees over the stock duration. The WR (racing model) cams have been re-ground to stock specs, and the WL cams to .360" lift and +10 degrees duration. Note that the WR cams take a flat tappet, which is unusual for a Harley, which accounts for their likewise unusual lobe shape.

The WL is for a trike and will be getting stroker flywheels as well as porting to give it a little extra power for a decent cruising speed. I'll try to post a little about that project as it progresses.

Donnie Smith Bike Show 2008

We are nearing a month since the Donnie Smith Bike Show was held in St. Paul this year. As usual, it was a huge success, and enjoyed greatly by exhibitors and spectators alike. This year's event drew over 16,000 through the doors.

One of the neat things associated with the show, was that my friend and customer Joe had his Flathead Big Twin displayed there. This is the bike who's engine was the subject of my series on a stroker Flathead engine build. Technically this was not its debut, since he rode it around Sturgis last summer, but certainly it was the first time it has been entered in a bike show. Congrats to Joe for taking home a couple trophies! His Flathead not only took best in class in the "Vintage Modified", but his display took an overall 2nd place for best display.

Joe's '44 Big Twin Flathead

Joe's display featured blown up pictures from the movie The Wild One. My guess is that hardly anyone there caught on to all the details of his display. He even had a trophy made up with the character portrayed by Marlon Brando's name on it!

More of Joe's display

Besides helping my friend Neil Ryan (the show's promoter) with set up, I also had a booth there to promote my business. Since the latest project bike I had in the works was nearly done, I spent the extra time to finish it up for the show. While I decided to display it in my booth rather than enter it in the show, I must say it received rave reviews.

In case anyone is interested, P2 (as I refer to it) is an 80" Knuckle using S&S flywheels and a Paughco frame; for sale at $23,900. Here are a couple pictures.

Check out the Holley downdraft carb!

My latest completed project.

A few other bikes which I had at least a small hand in over the last year are pictured below.

I fit the main bearings on Jason's Pan. He took it from there.

Kevin's Knuck motor was completely rebuilt in my shop, finished just in time for the show.

Hard to believe that just 2 weeks prior to the show I was replacing the exhaust spigots on Dave's Pan. Kokesh did the balance of the work.

Piston Survival Training

Any time you start dealing with old Harley engines with cast iron cylinders, there will be some concern about piston "scuffing", "scoring", or "sticking". All pretty much the same incident, just a matter of degree. In this installment of my series on the Stroker Flathead Engine Build , I would like to address this issue.

I have touched on this issue in another post, The Great Knucklehead Cylinder Controversy . Scored pistons can be a heartbreaking proposition when it leads to a broken cylinder. Its not much fun even if it only causes enough damage to require an overbore. Having seen so many badly scored pistons come out of cast iron cylinders, I was naturally concerned about how the pistons would hold up in this Flathead.

Pistons stick, score, or scuff for one reason. The piston gets hot enough that it expands to the same size as the bore, leaving no clearance. Having too little clearance initially is only one of a number of possible causes. Lack of oil on the skirt can be one culprit. Lack of cooling (sitting in traffic) can be another. Retarded ignition timing and lean mixture are others. Add to that the fact that cast iron motors like Knuckleheads, Flatheads, and Iron Sportsters just tend to hold a lot of heat and you can see the potential for disaster!

In recent years I have been getting the piston skirts for Knuckleheads Teflon coated. The Teflon does a couple of things. It gives an extra margin of "lubricity", but it also allows you to run a little more clearance without fear of getting noise from piston slap (the Teflon coating "dampens" the sound). When Joe (the owner of the Flathead) brought up the idea of having additional coatings done, it sounded like a good idea.

What we wound up doing was having the piston skirts coated with a Teflon and the domes with a ceramic. The ceramic reflects the heat rather than letting it "soak" into the part. Most of the heat which ends up in a piston comes through the top due to being exposed to combustion temperatures. The ceramic should keep the pistons cooler, and thus less likely to stick. The Teflon on the skirts will give an extra level of protection in case of a break down in the oil film.

Added to this we did a ceramic coating on all parts of the combustion chamber (on the Flathead that means both the head and cylinder) including the face of the valve. We also ceramic coated the back side or "tulip" on the exhaust valves and the exhaust ports. Now with all those surfaces having a ceramic coating on them to limit the amount of heat soaking into them, this should be one of the coolest running Flatheads around.

One last thing. Likely not needed, and something you would want to do on a stock looking motor, but I added piston skirt oilers. With some careful measurements I determined that oil ports could be added to the cylinder flanges front and rear of each cylinder. Not any extra room here, so if you choose to do a similar modification be careful ! The holes need to be low enough that they are below the oil control rings with the piston at bottom dead center. Whatever fittings you use have to be small enough to clear each other in the "V" between the cylinders. I used some fittings from Clippard which were a #10-32 thread, 90 degree with 1/8" hose barb. Thses fitting are normally used in pneumatic air control devices. The actual hole going into the cylinder I limited to .050". Like I said, there is not much room for error here. I fed the oilers by way of a "T" in the oil pump return line.

Between all the teflon/ceramic coatings and the piston oilers this Flathead should prove to be about as bulletproof in the area of piston scoring as you can make it!

Let's Back Up a Moment

In my continuing series on the Stroker Flathead Engine Build I find that I have inadvertently skipped a couple steps that I should have mentioned. My most recent post in the series, Stroker Clearance and Flywheel Balance , brings us to the point of assembling the flywheels. However, I never did get around to explaining what was done to "fix" the problem with the rods that I mentioned in the post on Joe's Flathead . So if anyone is actually following this series, they are likely wondering why I would balance the flywheels with rods that were too narrow not to mention cracked!

Well, the answer is that I wouldn't. Knowing the high cost of replacement rods ($513 from V-Twin) and the likelihood that the new rods would also need to be honed to round before use, we decided to do the best we could with what we had. I sent the old rods to be magnafluxed by a local gentleman who specializes in aircraft engines. This showed cracks as I had suspected. My aircraft engine specialist recommended having the cracks welded, re magnafluxed, and then shot peened. That was the coarse we chose to take. Hind sight being 20/20, if I had realized at the time that the rods had been ground narrower, then I likely would have gone with new rods.

Once the rods were repaired, new races installed, honed to round, and bearings fit, it was time to do an initial assembly of the flywheels to determine the width of the flywheel assembly. It was during this initial "mock up" that I discovered the huge rod end play.

The reason that I needed the crank width info had to do with the Pinion race in the crankcase which I also talked about in my post on Joe's Flathead . The race needed to be removed from the case due to being spot welded into the case; not exactly an approved procedure. I have found over the years that once you start replacing case races in these old motors, there is a pretty good chance that you will have no flywheel end play even with the thinnest of end play thrust washers. This is due to the replacement races having a wider inside lip than the originals. I often wonder if the manufacturers of these replacement parts never had an OEM part to work from, or if they just lack any measuring instruments.

In any case, I knew that with a new race going into the right side, flywheel end play had to be taken into account. My first thought on the rod end play was a shorter crank pin, (one is available) but that would not bring them together enough. My next thought was thicker flywheel washers (the ones that are staked into stock flywheels on each end of the crankpin). Of course the S&S flywheels don't have washers there, but I knew that the flywheels could be machined for them, so I called my S&S tech rep. He suggested that it would be just as easy for me to send the wheels back to S&S to have the tapers machined deeper into the flywheels to bring them closer together. So that's what we did.

Now by the time you add up the cost of machining the flywheels, magnaflux, welding, shot peening, and shipping, suddenly the new repop rods don't look quite so outrageous in price. Like I said about hindsight....

As for the right side case race, that also posed a problem. After cutting through the spot welds, the race came out very easily; obviously that was the reason for said spot welds. Upon measuring the race and case, it became apparent that this would take unusual steps to repair. The race was already a +.025 and loose. The only good solution I could think of was to bore out the case and sleeve it for a new standard race. That was accomplished by bolting the right case to the table on the mill with the cam side down, bolting the left case to the right and then indicating on the left case race. Once the table was locked down the left case could be removed for easy access to the right side bore. Then a steel sleeve was fabricated to be a press fit in the case as well as give a press fit to the new standard race. By the time the new race was line lapped to size, we had perfect alignment of the two races.

So that should bring us up to date with my most recent post in this series. In my next post in this series, I will try to get into some issues having to do with eliminating piston scuffing.

Stroker Clearance and Flywheel Balance

This is the 6th in a series of posts on a flathead big twin engine build that I am doing in my shop. The series starts with Stroker Flathead Engine Build , and last post was Relieving the Flathead . Once the rods are rebuilt, and the cylinders are bored it is time to mock up the engine and do some clearancing for the stroker. Because of the extra stroke, the relationship between the rods and the cylinder spigots, cases and even the bottom of the piston skirts has changed and all of those clearances need to be checked.

The first thing that needs to be addressed is to check that the male rod does not "bottom out" against the inside of the female rod when the pistons are at bottom dead center. Now for standard big twin rod lengths, S&S provides a measurement. With the rods on the crankpin you simply measure with a caliper between the wrist pin bushings at their nearest point. On a flathead with it's longer rods it is a little more complicated, but can be accomplished by checking the measurement between the wrist pin bushings as per the S&S method, and then comparing to the measurement taken from wrist pin to wrist pin with the pistons and cylinders mocked up as in the center picture below. Any extra clearance needed is accomplished by careful grinding on the inside "webbing" of the female rod. (the mock up shown below is done by assembling the crankpin and and rods on one flywheel half and installing in a case half)

Other areas that need to be checked for a minimum of .060" clearance are; piston to piston at BDC as shown in the center picture above, piston to flywheel also shown in the center picture, and rod to cylinder spigot and crankcase as shown in the other two pictures above. Note that it is possible to check these clearances with the flywheels fully assembled, but it is much easier to see the piston to flywheel when performed with only one half.

Once all stroker clearances are verified, the flywheels can be balanced. In this particular case, though, I felt it would be worthwhile to lighten the pistons as much as practical in order to lessen the stress on the antique connecting rods. Lightening pistons can be a real art (or science) in itself, and there are businesses that specialize in that sort of thing. The key is to avoid weakening the piston or distorting it. I have lightened quite a number of pistons over my years of drag racing, and so felt comfortable in doing the work myself. Yes, the pistons undoubtedly would have come out lighter if I had sent them to a specialty shop, (mostly due to my being conservative) but the extra expense was not in the budget.

With the pistons as light as I was going to make them, it was time to balance the flywheels. Most of the shops like mine that perform flywheel balancing use basically the same static balance method. Some may try to tell you that static balancing is antiquated and the real way to balance flywheels is dynamically. They may be wrong. The people over at Darkhorse Crankworks (respected experts in the field of Harley flywheel balance) have written an interesting piece on the subject that you can view here: http://www.darkhorsecrankworks.com/pdfs/nospin.pdf

Static balancing of Harley flywheels is a process of weighing the individual pieces (crankpin, bearings, retainers, rods, pistons, rings, wrist pins, etc.) computing a balance bob weight from those figures and employing gravity to tell you when you have achieved a "balance". The actual modification is done by drilling holes in the perimeter of the flywheel. I put the word balance in quotes because on a Harley engine with its v twin configuration, what you are really striving for is the best compromise for the least vibration in the rpm range where the engine will spend the majority of its time. You will often hear the term "balance factor" used in relation to Harley flywheels. This is the % of the total reciprocating weight that is added to the rotating weight to give the bob weight. My personal rule of thumb is to use a 60% factor for light flywheels such as S&S (where both flywheel halves are about the same size) and 55% for old style OEM flywheels (where the left flywheel half is considerably heavier) Last time I counted (8 or 9 years ago) I had balanced well over 100 sets of flywheels using this method without any negative feedback.

Last row of pictures, from left to right: Weighing crankpin, bearings, etc. Balance shaft and bob weights. Static balancing one flywheel half.

Relieving the Flathead

The second half of "port and relieve" is, of course, "relieve." It refers to the process of removing material between the edge of the valve and the cylinder bore. This is done to facilitate airflow, the thinking being that removing material in this area will give a better path for the fuel air mixture to travel as it exits the valve and makes it's way down into the cylinder.







The "relieving" had also been done on Joe's cylinders well before I got to them. As with the stock size intake valve and grossly oversize exhaust valve, the relieving had been done favoring the exhaust. In other words, the relief had been made deeper between the exhaust valve and the bore than between the intake valve and the bore. There was not a lot that I could do about this, other than smoothing out the job that was already done and making the reliefs the same from cylinder to cylinder.

I was alarmed at one point that the top ring would be too close to the bottom of the exhaust relief, exposing it to too much heat. As it worked out, by the time I had fabricated a thin "stroker" plate to go under the cylinder base to adjust the squish, the top ring was a safe distance below the relief (barely).

Now...., the way I would have liked to have approached the matter of relieving is a little different. What I would have liked to have done is treated the area between the valves and the cylinder bore like a port. Consider the floor of the "port" to be the area between the valve and the cylinder bore, which would make the roof of the port to be combustion chamber in the head. My thought is that the floor would respond better to having each "end" radiused rather than the entire floor lowered. If the actual size of this passage between the valve and cylinder bore needed to be enlarged, it may be better to remove the material from the roof.

Alas, with the relief work that was already in place on these cylinders, there was little to be done in the way of research and development.


Another area that was an obvious problem area was in the valve pockets in the heads. In fact, during initial mock up, not all of the valves would even open completely with the heads in place. Opening up the heads to match the head gasket solved the clearance problem, as well as unshrouding the valves for better airflow. Whether this interference was entirely due to the oversize valves or not is questionable. Joe had purchased new reproduction aluminum heads for his motor. Many of the head bolt holes in these heads had to be modified in order to allow them to align with the gasket and the holes in the cylinders. (Having to modify new aftermarket parts to make them fit is pretty much the standard of the industry, so please keep that in mind next time you think your local Harley mechanic charges you too much or is too slow) If the manufacturer could not even get the head bolt holes in the right place, what are the chances the chambers in the heads were put in the right place? And yes, there are apparently several different manufacturers of these heads, so don't condemn all of them because of my bad experience. I just received another set of aluminum side valve heads from a different manufacturer for another customer and the head bolt holes all lined up perfectly.











One last note, the intake manifold also needed a bit of work. I already knew that a deep V in the manifold hurts flow from testing I had done on Shovel and Evo manifolds. Since this manifold had to be made slightly wider to make up for the stroker plates, and I also wanted to convert to a "rubber band" style seal in place of the "plumber style", it only made sense to fill in the V while I was welding. With the V filled in from the outside, I was able to open it up on the inside without grinding through. I fabricated a couple of sleeves to widen the manifold as well as increase the O.D. to the came size as the intake spigots.











More than a few trips to the flow bench were involved to verify and provide future reference.

Prepping the Flathead for Porting

As noted in the previous post on Joe's Flathead , these was some serious discrepancy in the valve sizes. The intake valves were stock diameter (1.940") but the exhaust valves were way oversize at 2.164". After some hemming and hawing and a bunch of measuring, I decided that by putting new seats in the exhaust I could reduce the valves size there to the standard oversize Rowe valve for a UL (2.050") without sacrificing air flow. At that point it only made sense to use the same oversize valve in the intake. Normally one would like to see a larger valve in the intake than in the exhaust, but in this case I felt we were doing pretty good to just get them back to the same size.

By comparing the first two pictures, one can see the 27 degree "backcut" that I added to the intake valves to enhance flow.

Once new valve guides were installed and sized, machining the cylinders for seat inserts was a piece of cake thanks to my Kwik-Way 044 seat and guide machine. After the exhaust seats were installed, the same machine allowed me to cut the seats with the special radius cutters in preparation for porting. If you have never seen this type of cutter, it is really pretty neat. On a standard 3 angle valve job, it cuts all three angles at once, and since the width of the 45 degree is built in, it is pretty tough to mess that part up. On the special radius cutters I have for porting work, the top angle and the 45 are normal, but from the 45 to the bowl is a specially shaped radius in place of the normal 60 degree angle. For the Flathead I used a cutter with a .060" wide seat in both the intake and exhaust for a little better heat transfer.

With the seats cut, it was time to go on to the porting. In any port job, the seat area in one of, if not the most important part in getting good flow. That part of the job is made much easier and more consistent with the use of the radius cutters. The ports themselves had previously been reworked by someone, so only needed a little shaping to make them good to go. The relieve job that had been done, well, that was another matter.
Next time we'll discuss the "relieve" part of "port and relieve" and also talk a little about valve shrouding and the heads.

Joe's Flathead

When you decide to hop up an antique engine you invariably wind up dealing with more complications than if you were doing similar modifications on a newer engine. Sometimes those complications are fairly easy to remedy, but sometimes budget restraints lead you to compromises. Such was the case with Joe's motor. As we opened it up we found some things that were not expected, and many of them were doubtless the result of compromises made by a previous owner. We can't fault that previous owner for these compromises , because we don't know why he may have made the decisions that he did. Parts availability at that time is just one of the things that may have been a factor.




The first obvious thing we found was that the motor had oversize valves and had been ported and relieved. At first glance this appeared to be a plus, but a closer look revealed that it would have been better if the ports had been untouched. First of all, while one of the valves was a generous oversize, it was the wrong valve. The exhaust was considerably larger than the intake, and the relieving was deeper on the exhaust side than the intake. The exhaust valve being larger than the intake could be explained by a badly damaged seat at some point in time, but this doesn't account for the relieving on the exhaust side being deeper than on the intake. Such a combination would seem to suggest plans to use a turbocharger at some point in time, but that is pure speculation on my part. Pictured here is the stock size (1.940") intake valve on the left and the oversize (2.164") exhaust on the right.

The next problem that was apparent was that the right case race had a series of 4 short welds around its outer diameter. Evidently someone had reason to believe that it would come loose without this modification. My first instinct was that if the race could be lapped to straight and round while maintaining acceptable clearances, that it would be best to leave well enough alone. After considerable "soul searching" I decided that it really needed to be addressed.


One last item that I noticed right off, but really didn't get my attention as it should have, was the fact that this motor had the pre 1940 open female rod instead of the updated one that you would expect to find in a '44 model. I say that it didn't get my attention as it should have because, while I noticed that it was an "open" female rod which is prone to cracking, I did not realize that it was from a earlier year. The picture at left shows the "open" rod on the left and a later "closed" rod on the right. Over the years, every time I have had occasion to rebuild a set of open rods, I have first had them magnafluxed. Each time they have proven to have cracks in the webbing at the bottom of the rod. This set was no different .

Much less apparent was the fact the female rod was narrower than a big twin rod. I assume this is due to the sides of the female rod having been ground at some point, rather than it being designed that way. If your rods have been ground to make them narrower, it would only be to increase the end play of the rods. If you need to increase the end play it is usually due to one of two problems; a mis-machined crankpin (too short) or flywheel tapers that are too deep (over tightened?). Either way, it becomes a problem when building a stroker, because both the flywheels and crankpin will be replaced, giving you excess end play. In our case we would have wound up with about .090" rod end play.

About now you may be saying to yourself "what a mess". And a mess it is; but the question is how do we fix it? If Joe was independently wealthy, we could have simply ordered new cylinders from Flathead Power, a new set of aftermarket connecting rods and maybe even looked for a good used right case half. But here is where the inevitable compromises come in. The trick is to make the compromises needed to keep the project financially feasible without compromising the integrity of the engine. In the pages to follow, I will attempt to document how we (hopefully) accomplished this.

General Info and Thoughts on Big Twin Flatheads

The flathead (also called a side valve) engine design has been around for many years. Harley first used it in a single cylinder version. In 1929 they came out with their first flathead v-twin , a 45 cubic inch. A year later, in 1930, Harley came out with their first "big twin" flathead, a 74 cubic inch with the "V" series of model designation. 1935 was the year that the V series received its first 80 cubic inch engine. 1936 saw the last of the V series flatheads and along with it the last of the "total loss" oil systems. Yes, that's right; hard as it is to imagine in today's high tech world, early Harley's did not have a circulating oil system. Once oil had served its purpose, it ended up on the ground.




















This change to a circulating oil system is one of the most notable changes differentiating the new "U" series from the older "V" series. 1937 and later U models all share the same 4 9/32" stroke. Both a 74 and 80 inch engine were still offered, the difference being in the bore size. The 74 had a 3 5/16" bore while the 80 had a 3 7/16" bore. A popular hop up "back in the day" was to use these longer stroke flathead flywheels in knuckle motors in place of their 3 1/2" stroke (61") or 3 31/32" stroke (74") flywheels. Harley continued to produce 80" flatheads until 1940, and the 74" until 1948.

So how practical is it to "hop up" a Harley flathead? The answer to that question will probably be different for every owner. How far you chose to go in modifying your flathead will, to a great extent, depend a on the use it will be put to, and the amount of money you have available to do it. The mods done on a motor that is your only ride, and daily driver, will quite likely tend to be milder than if you own 3 bikes and this one is "just for fun". Flatheads have been modified to increase their performance for .... well, probably about as long as their have been flatheads. There are some mods that might be practical from a longevity standpoint which are not practical financially for many of us. Obviously if you are bothering to read this, there is probably something more than ultimate horsepower motivating you, or you would not be contemplating hopping up a flathead; you would be replacing it with something more modern. But some of us just see the beauty in making something antique run way faster than it was designed to run. Guess that's part of what makes a person a "gearhead". Which modifications you decide to do to your flathead may hinge to a big degree on the condition that it is in right now, unless money is not a issue.





Stroker flywheels are not cheap, nor is the labor for installation, but unless taken to extremes are probably not a big factor in longevity at the rpm most street engines will be run. Flywheels can become unusable, usually due to damaged tapers. If such is the case with yours, then stroker flywheels become an attractive option.
Increasing the duration of the cams will get more air in .... and out; increasing power. Again, unless taken to extremes, this will not decrease longevity to any great extent. Cam duration will, however, effect the rpm range at which the engine will make its power. A higher lift cam will tend to increase the power over the entire rpm range, assuming the heads flow more at the higher lift than they did at the stock cam's lift. Keep in mind however that nearly all cams that have increased lift also have increased duration. This is probably not something that should be a matter of concern for a couple of reasons. #1 Most cam grinders know what they are doing, and won't steer you wrong if you tell them what mods you have done on your engine, and what you are looking for in performance. #2 If you are having your stock cams reground, the material that the cam grinder has to work with is probably not enough to create a cam that is going to be too "hot" for your motor. Having your stock cams reground to "hotter" specs could possibly even save you some money if the lobes have unacceptable wear , but the shafts are still usable.

Porting, done correctly, is win/win situation. Porting is the act of physically modifying the shape and/or size of the passages from the carb to the intake valve and from the exhaust valve to the exhaust pipe. Without a flowbench you will have a tough time measuring the results of any modifications you make here. On flathead engines, usually the term "relieve" goes hand in hand with "porting" (ie.: port and relieve ) Relieving is the act of physically removing material from the cylinder between the valve and the bore to aid in air flow. While this is a time tested modification, it will have the effect of lowering the compression ratio. Popular opinion is that to make power with a flathead, airflow is more important than compression ratio. I have some thoughts of my own as to the method that is commonly employed in relieving, which I will share later in this series of posts

Stroker Flathead Engine Build

(I originally started to post this series about a Flathead build on my website, however due to ongoing issues with that web site coupled with the ease of posting on this blog have caused me to move it here)

Some time ago Joe approached me about doing an engine rebuild on the 1944 big twin flathead motor that he had recently acquired. He indicated that he had been gathering parts to build it as a stroker, and wanted to know if I would be interested in doing the engine build as well as some porting work. Well, anyone who knows me, will tell you that I am one of those who still believe the words "high performance" and "antique" can still be used in the same sentence together. In the following pictures and posts I am going to attempt to follow the process in pictures and words while giving some (hopefully) good technical advice. If any of you would care to offer their opinions or advice, please feel free to comment.

These are a few "before" pictures. Wouldn't you love to have the vintage S&S carb cover? Heads are cast iron painted silver.