eschaider - Modular Fords

  • eschaider

    by Published on 07-11-2019 02:56 PM     Number of Views: 20 

    ModMotors bring a variety of new challenges to the engine builder. One of the more painful is cam phasing. I have followed the tried and true path most of us have or are following in our engine builds. During this death by a thousand cuts it occurred to me there was an easier route available to us, that I have never heard anyone suggest — so I am going to.

    This approach uses a homemade fixture and an Excel Spreadsheet to dramatically shortcut the entire process. To start out you will need to fabricate a fixture to hold two dial indicators simultaneously, and a TDC tool to make finding TDC easy and accurate and that’s about it.

    This is what the homemade fixture for the dial indicators looks like. This is the front view;



    And this is the back view;



    The split collet gizmos for locating the dial indicators are Starrett items and as you might guess come at a relatively dear price of $25 to $30 each depending on where you buy them.

    The fixture itself is very simple. It bolts to the head at the cam cover attaching screw holes. I used two chunks of aluminum for the indicator mounts and sized them to place the indicator probes just above the valve stem on the tip of the cam follower. To make angle selection easy I used a small stud and wing nut to snug the fixture down so it would not move around during cam phasing.

    The next homemade tool you will need is a ModMotor specific TDC tool that is long enough to stand above the sparkplug well when it is installed in the head. I took a spark plug, removed the porcelain and machined an aluminum shaft to push in and protrude into the chamber an inch or so to stop the piston before it reaches TDC. This is what it looks like;



    When you install it in the head, this is what It looks like;



    This makes it very easy to install and remove the TDC tool any time you feel a need to check your TDC mark on the degree wheel.

    I like the Jomar style degree wheels. Mine is a 40 year old version. The Jomar approach to degree wheels uses a collet held to the snout of the crank by the crank stud. The collet has a jam nut to lock the degree wheel wherever you wish. I built a homemade TDC pointer gizmo out of a dial indicator swivel clamp, two lengths of mild steel rod and a $1.50 block of optically clear plastic from Tap Plastics. This is what the pieces look like;



    And this is what it looks like on the engine block;



    OK now to the fun part. There is a downloadable XL spreadsheet at the end of this post that I built to take the burden of doing all the math, in real time as you are trying to phase the cams, off the engine builder's shoulders. The spreadsheet has one sheet for the Passenger Side cams and one sheet for the Driver's Side cams. This is the Driver's Side Cam Phasing Worksheet;



    The only numbers you need to enter are the 0.050” before max lift crank position number and the 0.050” after max lift crank position number. The spreadsheet does the rest for you. The spreadsheet will also accommodate the now unavailable Cloyes 9-Way secondary sprockets, if you are fortunate enough to have them.

    Lets put some numbers in. You only enter data into the yellow cells, all the green cells are calculated for you. First thing we want to do is put the cams in straight up with all the 9 ways and the hex adjust set to 0. When everything is set to zero and the pre and post max lift points are entered in crank degrees, this is what we get;



    Remember you only enter the data into the four yellow cells. The spreadsheet will calculate the individual lobe centerlines for both the intake and the exhaust, along with the lobe separation angle (LSA) and how much the cams are advanced or retarded, in this case 0.75˚ retarded.

    Lets say that I wanted the engine for a street use vehicle so I am going to look for somewhere between zero and -10˚ of overlap so my idle bypass still works reasonably well. Using Mark Olson’s great CamCharting tool we find the following phasing will provide a -3.5˚ overlap target.



    Marks CamChart tool confirms an LSA of 114˚ advanced 2˚ will provide -3.5˚ of overlap and open the intake valve at exactly TDC.

    Soooo, what do we do now?

    Time for the Cam Phasing Worksheet. We already know the cams are at a 109.25˚ LSA with everything set at 0. We want to be at an LSA of 114˚ so lets do this,



    By installing the Cloyes 9-Way intake sprocket in the 4˚ retard position we can open up the LSA from 109.25˚ to 111.25˚. Cloyes only provides +/- 4˚ of freedom with their sprockets which means we are still 2.75˚ from our 114˚ LSA target.

    If you use another Cloyes 9-Way adjustable sprocket on the exhaust cam it will not change the exhaust phasing but it will change the secondary drive chain phasing with respect to the intake cam. This time though the changes are counter intuitive. Installing the sprocket in a retarded position on the exhaust actually advances the intake cam and vice versa if you use the advance settings.

    Lets take the Exhaust 9-Way and advance it 4˚ which is the equivalent of retarding the intake 4˚ and increasing the LSA by 2˚. This is what it will look like;



    Now we are at a 113.25˚ LSA. Because of the indexing limits on the 9-Ways of +/- 4˚ this is as close as we are going to get to a 114˚ LSA. We are still confronted with the fact the cams are retarded 4.75˚. To fix this we need to advance both cams 4.75˚. The Cloyes Hex-Adjust range of adjustment as specified by Cloyes is +/- 4˚ however most Cloyes timing sets can sneak up on a +/- 5˚ adjustment range. Let’s set our Hex-Adjust all the way towards it advance limit of 5˚. When we do that the Cam Phasing Worksheet will look like this;



    Now we have the cams at a 113.25˚ centerline with a 0.25˚ advance. We wanted a 2˚ advance but that was not in the offing because of the Hex-Adjust design. Cloyes elected to make the range of adjustment on the Hex-Adjust +/- 4˚, to reach our 2˚ advance target we would need an additional 4˚ increase in the range of advance from +/- 5˚ to +/- 7˚.

    A crank sprocket has 21 teeth on it which means each tooth is the equivalent of 360/21 or 17.14˚ of crank rotation. To avoid getting caught without enough adjustment range the hex-adjust would need to have a range of +/- 8.57˚ or one half of the angular displacement in each direction of a single tooth on the crank sprocket. Because 8.57˚ is a clumsy number to work with, the range ought to be set at +/- 9˚ or a little more than twice what Cloyes has provided.

    Currently there is no clean fix for the reduced range of adjustment with the Cloyes hardware and like the example above, the enthusiast would have to settle for close to but not precisely what was he was shooting for. To be fair this shortcoming does not usually manifest itself but can, as it did here. Whether or not it will affect your install depends on how the cams were ground and where you elect to install them. All things being equal, the Cloyes package is still the best available for our engines today — even if some parts are hard to come by.

    Most significantly from an effort on the builders part perspective, the entire cam phasing process has required only two measurements. The first was the initial look see with the cams installed at zero on all the hardware to get your starting point. The second and last install was to set the cams as close as physically possible to your target phasing and then confirm their phasing with one last measurement. You follow this process once for each bank and you are done. When you compare this to the hours of repeatedly installing, measuring, making calculation mistakes on paper, reinstalling and remeasuring to achieve the same result — this is clearly the much easier way to get the job done.


    Ed
    by Published on 10-31-2018 10:33 AM     Number of Views: 369 

    One of the more frequent and emotionally charged PM questions I get on a regular basis is why can’t I bore my block 0.020” or some even ask 0.040” or 0.060” oversize. The simple answer is there is insufficient cylinder wall available to support those dimensions. That is usually followed by a proof point being offered that my good friend has bored his block that much and he makes XXX RWHP and is very happy.

    The statement begs two questions;

    1.) If you are so comfortable, why are you PMing me asking for my blessing to do the same thing?
    2.) How frequently and how long has his engine run at max power with this configuration?

    The simple truth is that when you have an engine with 100mm bore centers and a 90.22mm bore there is precious little material left to support any bore increases let alone bore increases on supercharged engines that are asked to perform at power levels several times Ford’s original advertised power level.

    Let’s look a little deeper into the how and why side of the issue using some Ford data. The image below, from a Ford print of a 4.6 block, illustrates the cylinder bore dimensions and geometry of a typical aluminum OEM 4.6L engine block.



    As you can see from the drawing the cylinder bore centers are set at 100mm. The combination of the liner and the supporting aluminum register the liner is located in come to 3.15mm or 0.124”. The print calls out a 3.5mm (0.138”) gap between the outsides of the two supporting aluminum registers.

    When we start to do the math beginning with the 100mm bore centers and then subtract 6.3mm (for liner and register) we come sown to 93.7mm. From the 93.7mm we need to subtract an additional 3.5mm (1.75mm on each side) for the coolant gap between the two aluminum cylinder registers which brings us to our standard bore size of 90.2mm or 3.551” in imperial units.

    Now lets go back to the 3.15mm liner and liner support between cylinders. Remember 3.15mm is 0.124 inches. Let’s say we leave a 0.062” thick aluminum register to support the cylinder liner. That means the iron cylinder liner is 0.124” – 0.062” or only 0.062” thick on a side! The aluminum register is actually thicker than 0.062. Let’s be conservative and hold to only 0.070” which means our cast in place sleeve has 0.124” — 0.070” or 0.054” thick walls.

    Imagine boring that block 0.020 over size let alone larger. At 0.020” over you only have 0.044” of liner wall left! For a daily driver you might be OK. For a mild 650 WHP car you are in the deep end of the swimming pool and you don’t even know you have to swim! A 650 WHP car is essentially a 750+ HP engine. That works out to a little over 3HP per inch and it only has a 0.044” thick cylinder containing all that power!

    On high powered, supercharged engines, thin walled liners like that distort under power allowing combustion gases past the rings and into the crankcase. Repeatedly doing this to the liners will ultimately cause them to work harden and crack. For any supercharged engine you want to maintain the best ring contact possible and the most rigid liner possible. That means the least overbore.

    It is also the reason I always encourage a new engine builder to find the worst cylinder in the engine and use that as the guide for piston and finished bore sizing. My suggestion will always be to go just large enough to clean up the bore top to bottom and then no more. The challenge with this historically has been that piston manufacturers only make standard, 0.010 and 0.020 oversize pistons.

    The reason I originally contacted Gibtec to ask them if they would consider offering a ModMotor line of pistons was that CNC manufactured pistons cut from billet stock had none of the limitations that forgings brought to the design table. It was possible to start with a clean sheet of paper and without compromise build the exact piston the engine needed!

    The fact that the CNC process would allow a custom pistons to be built in 0.001” increments to any size was a huge plus! Equally as attractive was the ability to order replacements that would match size and weight of the originals to a gram and a thousandth of an inch.

    The reason that having pistons in 0.001” increments is so valuable for OEM blocks is the preservation of the already oh-so-thin cylinder walls in the OEM block. The real fix for the problem is the use of an aftermarket liners like LA Sleeve offers.



    The LA Sleeve Modmotor liner has a outside diameter of 3.793 inches. Using a 3.551 inch bore will provide a cylinder wall thickness of 0.121 inches or just shy of an eighth of an inch!

    The near eighth inch liner wall thickness and improved nodular iron liner material provides a substantially stronger liner than the thin less than a sixteenth inch OEM liner wall alternatives. The more robust liner stays round under high boost and high power and if necessary can be easily replaced on an individual basis. Additionally the full flanged approach to registration provides the necessary real estate for a receiver groove allowing copper gaskets and a stainless o-ring to be used for a dramatically improve head gasket seal.

    Could you go 0.020” over on a replaceable liner — sure. You would still have 0.111” of cylinder wall left but it begs the question why? If you do, you need eight new pistons, a new set of rings, a complete boring and honing and a rebalance because the rotating assembly has just changed. This is a look from the crankcase side where you can see just how heavy the LA sleeve cylinder walls are.



    The replaceable liner lets you replace just a liner if it gets wounded and reassemble. Worst case you order a single replacement piston from Gibtec and it will arrive identical to your original including weight. Better yet order ten pistons from Gibtec on the initial order — it is less expensive. Slide the new piston in the new liner and you are good to go. There is no need to rebalance the crank or any of the other usual rebuild monkey motion.

    This is what a block looks like with aftermarket liners installed from the top.



    And here is a picture of the block with liners and a few pistons installed



    When you add head gaskets this is what they look like on the deck,




    Ed
    by Published on 10-13-2018 12:09 PM     Number of Views: 712 

    This fix was originally published in Joe Goffin's Aluminator Gibtec Build Thread

    OK guys here they are and some pics of how they were made, some additional photos similar to Joe's about how the disassembled tensioners look and where they go as you reassemble.

    I started with a 1 ft length of 3/4" 095 wall, seamless 4130 tubing because that was the closest that McMaster had to the size i needed. This is the tubing from McMaster. Aircraft Spruce will be less expensive than McMaster for the same tube;



    I started to clean up the end with Scotch-brite™ and then decided it would be easier in the lathe so this is how it looked after a few seconds and Scotch-brite™;



    The next job was to face off the end to make it square and chamfer the edges prior to parting off a piece. This is the parting off operation, you want the finished spacer to be 0.200" long.



    After the parting off I broke the sharp edge next to the cut off and the job was complete. Repeat this one more time and you have two pieces. Total time was about 30 minutes plus clean up.

    The spacers fit below the existing plunger as Joe has already indicated and prevent the chain tensioner from allowing the chain to go totally slack when the engine is shut down. This is a pic of how they fit into the tensioner assembly;



    When you use the spacers the ratcheting plungers are no longer required.

    There are a number of components in each assembly and as luck would have it they are different side to side. As a result I highly recommend you do one tensioner at a time and when you are done place it in a poly bag with all it's internals. Here is an exploded pic of most of the internals;



    The right tensioner piston has a lubricating hole drilled in its top center. This piston will have a black plastic metering disc that goes into the inside top of the piston. The left tensioner piston will have no lubricating hole and no metering disc.

    The ratcheting arm that we normally cut teeth off of is no longer required and can be discarded when you use the spacers beneath the tensioner piston. The metering valve you see in the pic below goes into the bottom of each piston well and is used to meter the volume of oil from the main galley that is fed to each piston to maintain chain guide pressure against the slack side of the primary drive chain.



    If you happen to remove it in the modification process be sure to reinstall it prior to final assembly of the tensioner. The metering disc goes in with the pictured side facing the movable tensioning piston.

    That's about it. This is not a particularly complex mod but it is a very good mod to do. The chain stretch at high engine speed or from a two step will cause the ratchet to extend on an unmodified tensioner and maintain tension on the primary drive chain as if it were stretched the way it was at high engine speeds — even after you shut off the engine.

    That primary drive chain tension will squeeze the oil out of the #1 cam bearing saddle. The next time you start your engine you will have metal to metal contact until oil pressure can be restored to that journal. Repeated performances like this will eventually scar both the cam journal and the bearing saddle in the head. The next act in this unhappy show is the seizure of the #1 cam journal in the head. This is accompanied by the breakage of the primary drive chain and all the collateral damage the engine is capable of heaping upon your wallet.

    Do the mod it is easy and the smart thing to do.


    Ed
    by Published on 01-31-2016 10:09 PM     Number of Views: 6659 

    The subject of fasteners comes up frequently enough that I should have organized this shopping list some time ago. Oh well, woulda, shoulda, coulda ... Here it is now. It covers every ARP fastener that is commonly used on our engines, how many you need and the torque or, in the case of the connecting rod bolts, the stretch required for proper installation;

    I have also provided a downloadable pdf version of the file as an attachment to this Article.


    Ed

    ModMtr ARP Fasteners.pdf
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    by Published on 09-14-2015 08:33 PM  Number of Views: 13131 
    Article Preview

    Here are a few hopefully provocative thoughts on the how's and why's of cam selection and phasing.

    Blower motors produce much higher cylinder pressures than their n/a cousins which is part and parcel to how they generate more torque and therefore horsepower. These higher cylinder pressures provide both benefits and challenges we do not have in n/a engine design equivalents. Those distinctions can be used to advantage as we approach cam phasing decisions for our engines. What I am going to share may seem at first, counter intuitive but it is as real as the supercharger on top of your engine.

    Lets use Comp 106450 cams and phase them to the crank like this;



    This is a fairly typical ...
    by Published on 07-25-2015 04:49 PM  Number of Views: 13182 
    Article Preview

    OK guys the deal is done and the numbers are in. Here are a few pics of the piston from different perspectives;

    Angled top view,



    Angled bottom / side view,



    Bottom view,



    Angled Top and side view,



    Thrust face view,




    To allow you to look to your heart's content I have also attached a 3D pdf file of the piston to this article. The file is named Gibtec.pdf. Download it and you can spin the piston around to your heart's content looking at it from all sides.

    What you see is basically 99% finished. There are little ...
    by Published on 07-05-2015 12:27 PM  Number of Views: 10078 
    Article Preview

    It has been a year or two since this was last a topic of discussion. At the time I did not have chain samples in my possession for two of the three most interesting chains, the Cloyes "Z" chain, and the Morse Japan HD chain. Since then I have managed to get production versions of all three chain sets. I have photographed all three side by side for visual comparison and also personally miked each ...
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