BRAAP

The seats have been cut. Next step is to blend in the chamber wall cut and the bowl hog to the ports, then surface the head, CC the chambers, pre assemble for valve train set up, etc. etc. etc. In the past, I have tried to get pictures capturing the different angles that are cut with the seat cutters but none of the previous pics really represented what was going on, very well. This time, I think I was able to take a decent shot of the seat work we perform using the Sunnen VSC seat cutters. I just LOVE these seat cutters for their precision, repeatability, finish quality of the seat face itself, etc. This first picture shows the cylinder head set up on the mill table with the cutting pilot installed in an intake guide. I then use the finger dial indicator and run it up and down the full length of the pilot in two directions to square the “head of the mill” to within .0001” of the pilot which is true in the guide. This keeps the “mill head” true to the valve guide so that the valve seat will be cut “square” to the valve stem, not tilted or canted. I then spin the finger indicator around the pilot to center up the cylinder head perfectly under the mill head, within .0001”. This allows me to cut the valve seat itself to within .0005” concentricity to the valve guide, (not offset to one side). Now I lock the mill table down tight, then double check all of my runouts in “X”, “Y” and “Z” just to make that tightening the table down didn’t disturb the settings, which it sometimes does when you are trying to keep such tight tolerances. This procedure is done for each and every valve seat that I cut. You may have seen or heard about a “seat & guide machine”. Serdi and DCM both make quality sat and guide machines. The seat and guide machine itself replaces the Bridgeport style mill that I use for performing seat and guide work, even though it uses the same cutting systems that we use here on the mill. A seat and guide machine is much quicker as its sets up much faster, but uses a bubble level and you are trusting that the table is plumb to mother earth, (or you should be double checking it once in while at least). I’ve used a DCM in the past. They are very convenient and are typically accurate enough for even high end production shops, as long as the operating is keeping tabs on the table/bed being level. This approach of using the knee mill is more precise even though it takes a little longer. With the mill, I know for darn sure that on each and every seat that I cut, that I am dead nuts on. This next picture shows one of the chambers with an Intake and an Exhaust valve. The valves themselves have purple lines on the seat faces to help identify the face and back cuts. The face is ground at roughly 44-44.5 degrees and the 30 back cut is 30 degrees to aid the air flow transition from the back side of the valve to the seat at low valve lifts, less than .100” lift. On the valve seats in the head, I marked the angles in green, with the offset green mark being the actual 45 degree valve seat face itself. The intake on this head has 5 angles, the exhaust has 4 angles. I try and get 5 angles as often as I can, but several factors dictate if I am even able to or not, such as new seats, valve head size, etc. With every head that we do, we are able to open the throat of the valve seat itself at least .040” sometimes as much as .060” over OE. This is like going to a larger valve without actually installing the larger valve itself. This modification is really only good for really high valve lift flow, at low valve lift, it doesn’t help. Of course actually installing a larger valve allows me to open the throat of the seat even further, but for most mild to moderate street L-series, this is not needed. For the Intake seat, the top angle in the chamber is 15 degree, then 30, then the 45 degree seat itself, then 60, then 70, then the bowl hog cutter which is the Blue marks, (the bowl hog is either 75 or 80 degrees, I forget which, forgive my poor memory), and then the port walls themselves. For the Exhaust seat, the top angle is 30 degree, then the 45 seat itself, the 60 degree, then the 70 degree and then the bowl hog. The green circle just left of the intake seat is the chamber wall relief cut which radiuses the 15 degree cut into the chamber wall and roof, (the 15 degree and chamber radius is actually on one cutter, as well as the 30, 45, and 60 degree cutter). On pretty much all of the valve seats we cut for N/A applications, whether it be Briggs and Stratton’s, Datsun L-series, or Little Block Chevy, we cut the Intake seats at .040” in width, and all the exhaust seats at .060” in width. Also, all of the Intake and Exhaust seats are exactly the same diameter as one another respectively and they are also cut to within .002”-.003” depth of each other respectively. On some boosted applications, we will cut the exhaust seats at .080” in width, this is application dependant. Of course, if the customer has specific seat geometry he/she needs to meet, we try to accommodate the best we can. Whew, back to work…

EXACTLY! I’m glad I’m not the only one whos L-28 was so finicky that it had to have separate summer and winter resistors. LOL A bone stock L-28 will tolerate quite a spread in AFR, but the more finely tuned for performance the engine is, the more finicky it becomes to AFR and even fuel quality. Finicky enough that during extreme temp swings from morning to the afternoon on some days, the engine will have slight misfires that you can ever so slightly feel/hear unless you reset your values. There is a little air temp sensor in the AFM, (that little white probe-nub looking doohickey), that is supposed to compensate for air density caused by temp variations, and it does a great job on stock engines, but for finely tuned performance cars, the ECU needs to have a more aggressive adjustment MAP in regards to that little sensor. FWIW, that little sensor in the AFM works just like the water temp sender, and that little air temp sender responds VERY VERY fast. It responds so fast in fact, I have used it as a tire pyrometer with a DMM. I did this back in the early ‘90’s. I just attached it to the end of an old ball point pen with the leads coming out of the back of the pen. I didn’t get actual temp values, (though it would be easy to calibrate it for that), I just used it to check for misalignment of toe and camber at the track when I used to run my cheesy 195 60HR 14” daily driver tires… (those were the days… LOL). have we gotten far enough off topic yet? LOL. I just love these discussions that get off on interesting tangents.

Oliver, You should not have any issue with running the resister in the cabin. In fact, the little black box sits on the center console for on the fly tuning/diagnosing. I was able to get in to Rons car to get picture of the little black box sitting on his center console, just in ahead of the 280 Z ash tray. Not that it has any relevance to what you are doing, but as for “ball park” OE water temp sender values, when the engine is dead cold, ambient temp of 70 degrees, the water temp sender value is typically between 2500-3000 ohms. With the engine at full operating temp, approx 180 degrees F, water temp sender value is typically 250-350 ohms.

Great thread to revisit. I may have missed it and if I did, I apologize for being redundant, but in regards to “sealing” the back of the car, I saw no mention of sealing the latch under the hatch and behind the license plate. These are areas that exhaust fumes from behind the car come into the rear hatch area via the vinyl interior cover of the underside of the hatch itself. Back in the early to mid ‘90’s when I had the dual exhaust on my L-28 powered 280-Z exiting out of the OE rear bumper holes, only about 2” out past the rear valance, I did get fair amount of exhaust fumes in the car. I had no fin, wing etc, see pic below… When I swapped in the V-8, I retained this exhaust arrangement, except it was dual 2.5” instead of dual 2”. So I set out to seal the back of car 100% from any air flow in or out. What I mean by the “back of the car” is the entire rear valence/taillight area. At first I recognized that even if the taillights are sealed good, and the rear hatch sea itself is in good condition, that the exhaust fumes can easily get behind the license plate and between the hatch and body itself, then up through the hatch lock, and into the space between the outer and inner hatch skin and ultimately into the interior through vinyl covering that allows access the hatch lock mechanism. In the first picture using a parts car as the example, the upper circle is the area between the hatch and the body of the car that needs to be sealed, (the bottom picture shows one method of using weathering strip to do just that). The lower green circle in the upper picture shows the latch hook as it is behind the license plate which allows exhaust fumes up into the hatch itself. (These pics are of a 280, the 240 would be similar). On my personal Z car back in the day, I just used duct tape to seal off the latch hook under the license plate. This is the BUBBA way out, but it did help. I’m sure that someone could easily make a Fiber Glass cup that could easily be attached under the license plate to seal that off, of course make it removable to be able to make hatch hook adjustments. Just thought I’d throw out my $.02

Charles, The sky is the limit. IT depends on how much research, fabrication, etc you want to put into this project. In short, evaluate how much that truck means to you, and then decide how much effort and money you are willing to invest. Without knowing how attached you are to that truck, (that would dictate just how far you are willing to go to squirt the truck), a Throttle body FI set up running Mega Squirt controlling both fuel and spark utilizing a dizzy would be a nice compromise in complexity, mileage, performance, and overall time invested in the conversion. You should at least gain mileage and drivability, and maybe some performance. If you could round up a multi port intake and injectors at a reasonable price, that would be even better. Even with the stock cam, I’m sure power would at least slightly increase as well as a nice bump in mileage and drivability once you get it dialed in dead nuts. Of course a nice torque cam would help power quite a bit and could even help improve mileage as the domestic OE V-8 cams are known for being WAY friggin anemic… Oh, and because you would be running a programmable EFI, even the emissions should improve, even with a nice EPA approved Torque cam. That’s my $.02. Good luck and keep us posted if you do pursue the Mega squirt avenue on your truck. There is a wealth of helpful info here and on the MS-EFI forum as well.

Silent, “CLICK!!!” It just now clicked what you meant by this question… As usual, another Paul (BRAAP) Ruschman dissertation… By taking advantage of the Helmholtz cycle, engine designers have been able to achieve greater than 100% VE at the extreme of engine development, i.e. “natural” supercharging. (I can’t remember if it is spelled Helmholtz or Helmholz. I do apologize for not knowing, as I should.) What is this Helmholtz cycle you ask? In lamen, the Helmholtz cycle is basically taking advantage of the fact that air has weight, (the mass of the air), and when that air gets set into motion, (flowing through a port), it now has energy. To fully understand and appreciate this, try this experiment. Take a long piece of PVC tubing, at least 5 foot long 10 foot is even better, or any tubing/pipe for that matter, say between 1/2 to 1” in diameter. Now blow through it and very quickly either put your tongue in the pipe or close your lips to stop the air flow. Notice how it tried to suck your tongue/lips though the pipe and you could feel a slight reverberation as well? That is the Helmholtz cycle you just felt. Those vibrations are pressure waves going back and forth inside of the pipe. The longer the pipe, the more effect it has. You also would’ve noticed that the strongest pulses were the first ones and they diminished over time, (rather rapidly). Try sucking through it and stopping the flow quickly as well. This time, the first thing you noticed this time is that the pressure wave tried to push your tongue/lips back into your mouth. Now lets apply to this to internal combustion engines. In the intake port of our engines, when the intake valve opens, the air gets moving due to the fact that the piston is moving down the bore, drawing the air into the cylinder, and the air flow moves quite fast as the port is small in comparison to the cylinder being filled, (just like when you sucked into that pipe). When the valve shuts, (you used your lips or tongue to stop the flow of air very quickly, but in the engine, this is exaggerated MUCH more as the pressure differentials are much greater, therefore the air flow is much greater than with your lungs on long piece of pipe), this column of air is still moving and now builds up pressure behind that valve, this pressure wave then surges back up the intake tract, then comes back, this would be the second wave, then it does this again, but with less energy, this would be the third wave, and the cycle repeats itself again and again. If we were tuning our intake tract for the second, third, fourth or even the fifth wave, then it would be at the point where either of these waves is just approaching peak pressure that we would want the intake valve to open, therefore allowing this column of air and its kinetic energy to “shove” even more into the cylinder than the piston could “suck” in on its own, ie. Greater then 100% Volumetric Efficiency, or VE for short Now remember, Torque output of any N/A engine is directly related to displacement AND VE. Have you ever noticed the Torque figures quoted for NASCAR engines, (I’m sure they are under stated as well)? For a given displacement, NASCAR is achieving some insane VE numbers from the lowly 2 valve push rod engine. There are other top echelons of Motorsports utilizing multi valve technology that are getting even more natural supercharging affect than NASCAR on N/A applications. Now keep in mind, engines that are able to produce this kind of power are VERY VERY narrow in the band they run efficiently. Run these engine below their optimum RPM range, and a nicely built/tuned hot street engine could kill them, say 2500-5000 RPM. I’m sure many of you are familiar with the L-98 TPI engines GM produced in the mid ‘80’s for the Camaro’s and Corvettes. In a good state of tune with a nicely matched cam, those engines pulled like freight trains! The power band was peaky, peaking at around 3000-3500 RPM, and then the torque curve would take a steep dive after that, running out of breathe by 5000 RPM. They could make as much torque as a carbureted big block that was 50-75 cubes larger. That was due to the LONG intake tract. The compromise was that they could not breathe above 5000 RPM no matter what you did. Some people have been able to get them to breathe at 5500 or so, but that is it, (yes they will all free rev to past 6000 but the power curve is DEAD up there, even with WAY radical cams, exhaust, big tube intakes, etc.) At the other end of the spectrum would be the LT 1 that replaced the GM L-98 TPI engines in the early ‘90’s. The LT 1 used extremely short runners, and as such, their peak torque output was much less, though the power band was much flatter across its operating range and because of the short runners, it could rev higher therefore allowing it to make more HP even though it couldn’t match the torque output of the TPI engines. (Torque is measured, HP is calculated. HP is calculated as Torque over time. The more torque you make at a higher RPM, the more HP you generate. Or if you can’t make as much torque as the next guys, at lest be able to make some torque at a much higher RPM and you will have a higher HP. It is the Power to weight ratio that wins the race, Torque is what you feel in the seat of your pants.) At any rate, this should kind of illustrate the idea behind intake design and tuning as it utilizes the Helmholtz cycle. Exhaust tuning is no different and all of this applies there as well, long tube vs short tube headers, etc… Hope this helps answers that question.

Oliver' date=' Since you are running the OE EFI, your best bet for across the board fuel enrichment is alter the water temp sender value. A 250 ohm resistor in series with your water temp sender might be enough to fatten your mixture for AV gas, if your AFR was pretty close to being with. As for using the AFM for adjusting the AFR, The AFM will only affect the AFR up to 4000-4500 RPM only and it doesn’t affect the AFR linearly. At WOT, the AFR has considerably less influence on the fuel map than it does at part throttle and idle, there fore the AFM would not be an ideal way to adjust your AFR for a swap to AV gas. For tuning OE EFI equipped cars, I use my little black box. This little black box is wired in series with OE water temp sensor for tuning purposes, (I even use it for diagnosing drivability issues some times as well). This black box consists of a small 3” x 2” plastic electrical box, a 1k ohm “linear taper” potentiometer, a fixed 1k ohm resistor, and a single pole double throw switch. All parts bought at Radio Shack, (I’d take a picture of the black box for you but it is currently in use in Ron Tylers ’78 280). Using my Fluke DMM, I then graduated the dial of the POT in 250k increments. 1k increments would be better, especially when dyno tuning. This little black box is a neat little tuning aid for the OE EFI. One position of the switch is just the POT, 0-1k ohms plus the OE water temp, the other position adds 1k ohms to the POT for a range of 1k-2k plus the water temp. This allows for VERY coarse adjustment, (if you are dyno tuning, just a 1k POT is MORE than enough adjustment.) Here is a picture of an example resistor with the bullet connectors on the ends and also a potentiometer allowing analog adjustment of the fuel curve on the fly. (The resistor pictured is just for example purposes, its ohm value is NOT desirable). You just unplug one of the water temp sensor connectors, either one it doesn’t matter, that is just behind the thermostat housing, (not the one with the red tape, that is the thermo time switch), and put the resistor in between the connectors and wa la, you will have a little fatter AFR. DO make sure that you protect the resistor from touching any metal parts as that could ground out the water temp signal causing the engine to run very lean, i.e. wrap it in electrical tape, heat shrink, etc. Hope this helps. BTW, did you get the E-mail I sent? [img']http://i17.photobucket.com/albums/b81/BRAAPZ/Rusch%20Motorsports/ResistorMedium.jpg[/img]

Here is a custom P-90a head that we are working over for a customer in the UK. We acquired this head here in the US, the casting number is P90A, yet the rocker pivots are the traditional solid adjustables and there are no oil galley ports in the bottom of the rocker pivot bosses, i.e. mechanically this head was cast and machined at the factory as a mechanical cam L-series head yet the casting number is P90A?!?!? Could this be a JDM head? Any how, the head is progressing along nicely, destined for a 3.1 stroker. These pics are of the completed ports and chambers just prior to installing the new valve guides. Guides will be shorted a little bit to keep as much of the guide itself out of the air stream. We will then cut the seats, CC the chambers, then after CCing the chambers, give the chambers a final finish, assemble the head with the Rebello cam, set the cam wiping pattern, order the appropriate lash pads, and ship the head to its owner in the UK. Depending on our schedule, we will post follow up pics of the progress on this head. We are also working on a Z-N-47 destined for another 3.1 stroker on the right coast, pics of that to follow as well.

Funny you mention the more accurate timing thing. Ron Tyler actually tested that on an L-16. It is dual SU carbs, had Mega Squirt running ignition only, EDIS-4 and he also left the electronic dizzy in and with his Fluke “O” scope, was able to verify how much scatter difference between crank trigger EDIS and the OE dizzy. I’ll let him reply the results…

FWIW, the currently available 100 LL AV gas has far less lead than it used to, pretty negligible any more, (I am a FAA certified Air Frame and Power plant technician a private pilot SEL, also professional engine builder specializing in L-series cylinder heads). AV gas is fine for auto engines. At Sunset Engine development, we used AV gas in pretty much all of the Gasoline powered white water race boat engines we ran on the Dyno as well as the 2/3 scale and ¾ scale P-51 Mustang kit plane V-8 engines. As has been mentioned by 1fastZ, AV gas is hard on Cats and over time will take its toll on O-2 sensors, though an O-2 will run for quite a while with AV gas. Our personal L-28 autocross car runs strictly AV gas and an Innovate LM-1 Wideband O-2. The engine is a Flat top piston L-28 with the MN-47 head, right at 12:1 comp ratio with around 42 degrees total ignition advance, no pinging or detonation, AFR at WOT is between 12.3-12.8:1 Now there is something that you DO need to be aware regarding AV gas. AV gas has less specific gravity than auto gas and race gas. This means you must either jet a little fatter or scale your EFI fuel map “up” just a skosh. If you plan to run it long term, definitely make it a point to retune your AFR as AV gasses lower specific gravity can burn a valve or worse. I’m sure many of you have heard horror stories that just by switching from auto or race gas to AV gas, you will burn up your engine. Yes, that is true and has been documented, but not because AV gas burns any hotter. AV gas burns valves due to the fact that theses same people didn’t recalibrate their fuel metering, i.e. fatten up the mixture due to lower specific gravity of AV gas so their engines were running too lean, that is what burned up their engine. Short term use like an autocross here and there most likely wont hurt anything, especially if your engine is running a little on the fat side with auto gas to begin with. If you are running on the lean side with auto fuel, then I would suggest you make a mixture adjustment, even if it is short term. Not only will this protect your engine from running too lean, but your AFR will be more ideal for maximum performance with that fuel. Octane rating an be viewed as a number that refers to the stability of the gas under certain conditions, Octane does not indicate power available in that fuel. In fact, as jmortenson mentioned, the more octane a fuel has, the less BTU’s available, i.e. less available power, but this is very slight. The trade off is that a higher octane rating is more stable and less prone to detonation, a trade off worth making for high compression race engines. In short, for maximum performance, run only as much octane as you need with ideal full ignition advance for the compression ratio of your engine. Hope this helps…

Bradman, Very cool. I have a few questions for you if you don’t mind. Who is building your MS controller? Will you been running MS-I or MS-II? Will your mega squirt be able to fire sequential COP ignition for a 6 cylinder, or at least a 4 cylinder? BTW, I’m assuming that you also own a Q-45 by your username, just curious, what year? I currently own a ’96 Q, no mods, black on black. The body/paint, interior, and power train is a 9 out 10, been a great car, but I would like to trade for an N/A Z-32.

OUCH!!! You guys are KILLING ME HERE!!!! Sorry, but as an engine builder/machinist, I must voice my $.02 here. Ok, those plugs you guys are referring to are actually called, “CORE PLUGS!” They are NOT “freeze plugs”… They got the misnomer of freeze plugs way back in the early 1900’s totally by accident, and by chance, that name stuck!! We engine builders get a full body chill every time we here a customer refer to them as “freeze plugs”….. OUCH! Please call them “core plugs”, please?.... Those plugs are there for the sole purpose of evacuating the sand from the sand casting process when these blocks are manufactured. It just so happens that approx 1-5% of the time, if the coolant freezes in an engine block, those plugs sometimes will pop out of the block, and that is how the term “freeze plug” wrongly came about. Then the myth started that these so called “freeze plugs” would protect an engine block from cracking if the water/coolant froze by virtue of those plugs popping out! Total and complete BS! Engine blocks crack ALL the time if the water/coolant freezes, even with today’s ultra modern casting technology, and those “CORE PLUGS, do not save the block from cracking!!!! PERIOD! In short, they are NOT freeze plugs! Now back to the L-series “CORE PLUGS”. Yes, there is one behind the bell housing, there is also one under the front cover, and one in the rear of the cylinder head as well as one in the rear of the EFI intake manifolds. On the L-28 blocks, there are nine 35mm “core” plugs on both sides of the block, one 40mm core plug under the front cover, and one 50mm core plug at the rear under the bellhousing. The back of the cylinder head uses a 35mm core plug as well. Core plug installation… When we install “core” plugs, we use a flapper sanding drum in a die grinder to remove all rust and sealant from the machined core plug orifice. We then use Permatex gasket sealer, (part 1A, comes in small tube), lightly smeared around the core plug itself and on the prepped core plug orifice in the block, and then tap the core plug into the block so that it is “just” beyond flush with the core plug hole, (flush to the countersink of the core plug hole). We have not had any leaks ever, using this technique. We, Rusch Motorsports, can get you the complete engine block core plug set in either Zinc plated steel or brass, or individual core plugs as well as the Permatex part 1A. E-mail us at ruschmotorsports@hotmail.com for current price and availability. For those interested, here are a few pics of the core plugs in a L-28 block, casting F-54. I also included a pic of the driver side of a VERY early, (serial number 2800), L-24 block, (bottom right), with its three “core” plugs.

I was asked via PM to describe in general COP and wasted spark ignition, in regards to use with Mega Squirt. My reply got so lengthy and with so much info I felt it best to post it publicly so that others could read it and also add to the gaps that I left behind. If anyone sees any errors in this info, please don’t hesitate to post corrections. The last thing I want is more “misinformation” thrown out to the public than already gets posted… Wasted Spark ignition systems as used by Chrysler, GM and Ford. I will use the Ford EDIS-“x” in the examples. Wasted spark means just that, one of the sparks ends up wasted. In a wasted spark ignition system, the “spark plug” in each cylinder actually fires twice per each cycle vs once per cycle as our typical dizzy ignition systems do. One upside to wasted spark is that there are multiple coils sharing the electrical load where as with a dizzy ignition system, one coil has to fire off ALL the cylinders by itself. That is quite a load for one coil to handle at high RPM, especially at WOT or even more so under boost… In a wasted spark system, the spark plug fires on the top of the compression stroke and once again at the top of the exhaust stroke, effectively doing nothing on the exhaust stroke, hence the term “wasted spark”. (It is the spark on the compression stroke that ignites the air fuel mixture in the combustion chamber which causes a chemical reaction releasing a lot of heat that pushes the piston down, rotating the crank shaft, then through the torque multiplier that we call the transmission, then through the driveshaft to the differential which not only multiplies the torque again, but also splits that torque to rotate 2 tires producing a nice light blue smoke cloud in-front of the neighbors house causing them to yell and scream at us for being so immature. Isn’t it cool?). On a 4 cylinder 4 stroke engine, by design, 2 pistons are always going up at the same time while the other 2 are going down at the same time. This means that one of those pair cylinders is actually firing when it comes to the top, while its twin is exhausting the spent gasses. With wasted spark ignition, those two cylinders are sharing the same coil. For inline 4 cylinder engines, this would be cylinders 1 and 4 on one coil, while cylinders 2 and 3 share the other coil. For inline 6 cylinder engines like our beloved L-28, cylinders 1 and 6 share a coil, 2 and 5 share another coil, while 3 and 4 share the third coil. Wasted spark is a very nice improvement over a traditional dizzy single coil ignition for a couple reasons. One being coil saturation time. More coils sharing the electrical spark demand allows for more RPM potential before the coil runs out of available duty cycle, (typical V-8 dizzy ignition systems like the GM HEI run out of optimum available duty cycle at around 5500 RPM depending on the coil design and how long you want the coil to last before it burns up). The other reason is more accurate ignition timing, AND, no gap between the dizzy rotor and cap that the spark has to jump across, also no cap and rotor to replace due to corrosion on the terminals. The Ford EDIS system uses an intermediate module called the “EDIS module”. This module is particular to the number cylinders of an engine. The EDIS module controls at what point the coils fire, coil saturation time, (duty cycle), and combined with a pulsed input from the Mega Squirt controller telling the EDIS module just how much ignition advance to fire off the spark plugs at, it makes for a great ignition upgrade over the OE distributor. All in all, the Ford engineers did a WONDERFUL job designing this system and it is how they implanted this design that lends the EDIS system to work independent of the FORD ECU, i.e. Mega Squirt control or for the Carbureted guys, Mega Jolt Lite Jr. C.O.P. is an acronym for “Coil On Plug”. That means one coil for each individual spark plug. This is yet another leap forward in ignition systems over wasted spark. Being as this post is already LENGHTY, I’ll just mention why, and if you are interested, the details covering these “why’s” are all over the internet if you search. In a wasted spark ignition system, the high tension leads of paired cylinders are in series so BOTH plugs HAVE to fire or neither of them fire. The air gap between the spark plugs themselves has resistance. The more air between the plug gap, (i.e. WOT or boost), the more the resistance. So, in effect, if one cylinder is running different than its ignition mated twin, the spark will also be affected for both cylinders because they are “ignitionaly linked”. (is that even a word? It is now…) I have heard there is another VERY slight pit fall to the wasted spark vs COP in regards to the direction the current flows through the spark plugs. Being as I have not looked into this, I’ll leave it to others that are “in the know” to elaborate more. COP eliminates this pit falls. Remember, wasted spark is still a drastic improvement over dizzy ignition, but COP is currently the pinnacle for production ignition systems. Plasma arc or full chamber ignition would be the ideal, but we are years away from that technology so we wont cover that. As mentioned, COP is the next evolution in ignition systems over wasted spark. In regards to the trigger wheel. Whether it be COP, wasted spark, or electronic control of timing while still retaining a dizzy, there has to be some sort of signal going to the processor to let it know where TDC is in regards to one of the cylinders, this is usually cylinder number one. (some of the more complex modern ignition systems through the use of cam AND cranks sensors, know which cylinder is at TDC on the compression stroke or pretty much any point within the 4 stroke cycle). As you probably already know, 4 cylinder 4 stroke engines, fire a cylinder once every 180 degrees of crankshaft rotation. 6 cylinder engines fire a cylinder once every 120 crankshaft degrees. 8 cylinder engines fire a cylinder once every 90 degrees of crankshaft rotation. Now each ignition system is specific to the number of cylinders being fired for that reason. I.E., (back the wasted spark Ford system), Ford produced four different EDIS systems. There is the EDIS-4, EDIS-6, EDIS-8 and the EDIS-10, each one corresponds to the number cylinders of that particular engine. All of these use the 36-1 trigger wheel and a matched Variable Reluctor, or “VR” for short, and it is the missing tooth that lets the processor know where TDC of the number 1 cylinder is at so that it can fire off the right cylinders at the right time with the correct amount of timing advance for a given RPM. (36-1 means a total of 36 teeth around the circumference, each at 10 degree intervals, with one tooth completely missing). Some Euro OE auto makers used a 60-2 wheel. Other auto makers use two separate wheels, one on the crank and another on the cam. This combo is capable of interpreting very precise piston location within the bore at any point within its 4 stroke cycle. Again, using the Ford EDIS system as an example, (EDIS uses only a 36-1 crank trigger wheel), with a 4 cylinder, if you were to use the EDIS-4 system, the EDIS module would know to fire one coil at “so many” teeth count, and then the next coil at “so many” teeth count again This applies to the EDIS-6 and EDIS-8 as well. So you can see, if you intend to use the FORD EDIS wasted spark system, you HAVE to match the module with the number of cylinders of your engine, i.e. EDIS-4 for a 4 cylinder, EDIS-8 for an 8 cylinder. Of course, you could use two separate EDIS-4 systems on an 8 cylinder engine, but that is beyond the scope of this post. ALL of the Ford EDIS systems use the 36-1 wheel. Another critical part of the EDIS set up is where you clock the VR sensor to the missing tooth in regards to TDC of the number 1 cylinder. When installing the EDIS system on the engine, it is imperative that you clock the VR sensor to the missing tooth at the specified location because the EDIS module is programmed for that position, or the plugs wont fire at the desired time, see attached pic below for VR sensor clocking to the missing tooth for the various EDIS systems. For COP using Mega Squirt, there is a lot more that you have to program and configure yourself, such as coil saturation time, how many teeth your wheel has and where your sensor is clocked, etc. etc. etc… The Ford EDIS is easy in comparison. All the info you need to make it run has been fully documented. COP is not for the faint of heart, though it is not impossible and COP does have advantages over Wasted Spark for extreme engines that spin extreme RPMS or engines that place extreme demands on its ignition system such as Sport bike engines, etc. I gather within the next couple/few years, it will be just as easy to adapt, set up, and configure a COP system as EDIS is today. Hope this is able to help answer some questions in regard to the alternative ignition systems.. Here are some other links that may be of interest along these lines.. Our EDIS test bench with some good pics as well http://www.msextra.com/viewtopic.php?t=14920 Our N/A L-28 240-Z with Mega Squirt and EDIS-6 Distributor less ignition. http://www.msruns.com/viewtopic.php?t=15436

Ohh Cooll… .. You work Lancair? Tell me more… Paul Ruschman Private SEL, (recently) and A&P back in ’91…

Contact us for a quote. We sell Center force as well as ZOOM clutch kits. ruschmotorsports@hotmail.com

Hmmmm.. Vetty vetty intahesting.. I'm intrigued...

Ouch, I hate it when that happens. Well a couple of things. You mentioned that you have “stiffer” springs, but just how much stiffer, a little stiffer or are these the recommended springs for that much cam at the RPM’s you spin? Also, a lot of the cheaper stainless valves are actually a three piece design fused into a valve, (valve stem tip, stem, and valve head). On rare occasion those three piece valves will separate/come apart at the fusion points and the result typically is what you experienced in those photos. We’ve seen this on more than one occasion with big lift cams. So you are in Bend eh.. Do you do much auto crossing in Eugene through EESCC or Medford at the Jackson county sports park?

And I quote… Hmmmm... LMAO...

Pete, Hmm.. Interesting. At this point, I would suspect dry would be OK. It would seem that a the SC would be better off to run dry vs having fuel run through it, i.e. gasoline is more of solvent than lube?.. BTW, are the Camden SC’s anything like the Eaton ones used on the GM 3.8 in the Pontiac Bonneville SSEi and Grand Prix GTP, or the Ford 3.8 Super Chickens? Those are run dry? Slightly off topic, but has anyone adapted one of those Domestic SC’S from the Ford or GM 3.8 to an L-series? Hmmmm…

The info that ezzzzz and the link that NCchris posted is info you can take to the bank. At minimum, allow your crankcase to breathe with a filter on the crank case breather tube. Those tubes are just pressed in so you can rotate it for better intake/exhaust clearance if needed, please don’t plug it. At best, a strong vacuum in the crankcase is ideal. The OE PCV system is VERY good middle ground as it does draw air through the crankcase via the head from that breather in the valve cover for all those reasons ezzzz stated. Better ring seal, less contamination of the oil from combustion fumes due to “blow-by”, and will also help keep your gaskets and seals from leaking, oh, and the greenies next door appreciate the fact that you are not allowing those noxious crankcase fumes into the atmosphere. If you are going to use the PCV system, you will need either a little filter on your valve cover breather port or leave it vented to the air intake on the ambient pressure side of the throttle valve so that it utilizes the OE air cleaner for its air filtration, i.e. OE set up. Good luck and keep us posted on your progress, Paul Ruschman