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Thread: Cam Phasing - An Easier Way
07-08-2019,†08:31 PM #1
Cam Phasing - An Easier Way
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 ó 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 thatís 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 0.050Ē before max lift crank position number and the 0.050Ē 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 Olsonís 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. Letís 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 looking 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 ó 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 ó this is clearly the much easier way to get the job done.
Last edited by eschaider; 07-11-2019 at 03:24 PM. Reason: Spelling & Grammar
07-09-2019,†08:37 PM #2
- Join Date
- May 2017
Ed, Thank you so much for this. This will really help once I start assembling!
07-09-2019,†08:58 PM #3
This type of information sharing is how these websites can lighten the load on all of us, Robert. If we share the success stories we each experience at different times in our builds, everyone wins. And it should go without saying that there is usually more than one way to do many of the things which means just because someone already threw a good idea up on the site, there is no reason someone else cannot add to the treasure trove with yet another perspective.
07-10-2019,†08:58 PM #4
- Join Date
- May 2018
Hi Ed this is a job that I have done many times the old way and wasted a lot of time. Thank you for sharing this awesome tool with us I will be us it for sure when finishing my new race engine.
07-11-2019,†02:42 PM #5
If you were one of the 9 members that downloaded a copy of the original Cam Phasing Master Workbook before the date of this post please download it one more time. The original which you first downloaded still had some development constructs in it. The current version is properly configured. The correct version of the tool is Rev 1.1 and the heading at the top of each page has been renamed from Worksheet to Workbook. you will find the Revision number in both the file name and also the banner at the top of each page.
The Revision 1.1 copy of the tool will open as a read only file. Do not be concerned by this. I did this to allow you to save individual copies of each cam phasing event as an individual file so you would have a cookie crumbs sort of trail to follow if you ever needed to. Additionally by requiring a save of each new file under it's own name you maintain the integrity of your template for future use. Each file you save under a project specific name is editable and resaveable under that same name. Even though you can use the same name I would encourage you to use names that you add revision numbers to inorder to leave yourself that cookie crumb trail to backtrack with just in case you ever need to.
My sincere apologies for the misconfigured original. Please download the replacement. Everything still works as indicated in the writeup in my post #1 above.
07-11-2019,†02:53 PM #6
One of the important things to remember to do is use square keys that have an intimate fit with the various cams and gears. If you don't the process is still doable you just need to maintain a tension on the chain drives like they see with the engine running. If the keys are allowed to wander in the keyways and gears the phasing job becomes more tedious.
Be sure to download the new version of the Cam Phasing Workbook I posted and discard the original if you downloaded it already. It had some development construct artifacts that I forgot to remove from the software. The Rev 1.1 version of the software is clean.
Last edited by eschaider; 07-12-2019 at 03:33 AM. Reason: Spelling & Grammar
07-11-2019,†05:35 PM #7
This is fantastic Ed. I (as Iím sure many others) are blessed to have you here (and a number of other members as well) on Modfords. The time and effort you continue to put in and the work and fruits you share with everyone is priceless in this hobby. I am getting my ducks in a row but will definitely be putting this method to use within hopefully a few months. I will be sure to start a build thread when I finally start putting the collection of parts and pieces together I have been collecting. Itís stuff like this and build threads like Jrgoffins and the countless other members who have documented the ups and downs when building these motors that keeps me coming back daily to check on anything new. I truly wish we just still had the traffic we used to have here before the facespace or mybook thing took over. I donít use those and probably never will do Iíll continue to check on things here and add what ever I can when the time comes.
Thank you and everyone else who still shows up and contributes to our great hobby!
07-12-2019,†03:31 AM #8
Thanks for the props, Ken. I think you will enjoy using the Workbook. It substantially reduces the PITA grief normally associated with the job.
A lot of the original guys from the site have sold their cars and bought newer rides to replace them so we don't see much of that crowd any more. Others that like the jousting and back and forth of the social media scene find those communities a better fit. Most of the guys still around here tend to be more of the hands on type of enthusiasts (like you) with both race track operation and street use for that special attitude adjustment time you can only find in one of these type of vehicles.
07-16-2019,†03:35 AM #9
Wow! What can I say, Ed . . . THANK YOU just doesn't seem to be enough. I am new to the Mod motor so I need to re-read this a few times before the impact of your method sinks in. I hope I can make contributions in the future.
All the very best.
07-16-2019,†09:20 AM #10
07-18-2019,†04:40 AM #11
Just starting to tear into a Teksid block. Are there aftermarket steel main caps for it? What is a good primary chain now that Cloyes has discontinued theirs? I have a set of "C" heads for it but don't know about compatibility (fitment) issues.
07-18-2019,†08:39 AM #12
07-18-2019,†11:29 AM #13
Everything Russ said is spot on saltfever.
Ford and the aftermarket do make two different primary chains for 4.6L engines. One chain is for the 03/04 SVT Cobra and the other is for everything else. The Cobra chain is referred to as a fine finish chain but beyond chain finish it is constructed differently. Here are pictures of the two side by side,
The chain on the right is the proletariat grocery getter model. The chain on the left is the fine finish 03/04 SVT Cobra chain. The two should be distinguished by the vehicle vin code. The Cobra code is VIN Y. Be sure to do a visual check before you leave the store.
A bit more trivia that is helpful is discriminating between the two. If you look in the picture the fine finish chain has 8 links and the proletariat chain has 9. The fine finish chain groups its links in pairs of two and the proletariat chain sometimes does and other times does not. Even though the fine finish chain has one less link it is the stronger chain. My guess, and it's only a guess, is that the links may be made of a higher strength steel and possibly are thicker. Without measuring the two side by side, link thickness is hard to tell from the picture but does appear to favor the fine finish chain.
Last edited by eschaider; 07-18-2019 at 11:32 AM. Reason: Fixed broken pic link
07-19-2019,†06:25 PM #14
- Join Date
- May 2017
07-19-2019,†09:16 PM #15
When it comes to installing those side bolts into OEM caps, I don't know if they will make it or not. The side bolt bosses on the original Teksid block look a little bit skimpy to put a 10 mm thread into. I put the side bolts into my HYland block but it was using John's millet mains that he did for the Hyland project. Even then the fit was nip and tuck. I drilled out the 9 mm threads the side bolts originally used. The drilling process is a bit tricky because you want to come just up to the 9 mm fastener's major diameter and stop.
I elected to use a thread forming tap rather than a traditional cutting tap because I didn't want to remove any additional material from the cap's side bolt boss for fear of a mechanical failure. After drilling to just shy of the major diameter for the 9mm bolt I used a reamer to clean up the hole to the spec size for a 10 mm thread forming tap. When the job was done I was absolutely in love with the finished product. The new 10 mm bolts are torqued to 62 or 65 ft/lbs (I have to look at my build notes to see which I used) and come up to that figure with a nice crisp click on the torque wrench.
Here is a pic of the 10 mm bolt next to the OEM 9 mm fastener,
Substantially better falls short of the mark in terms of expressing how good these fasteners really are.
The pic below is of the main caps installed in the bloc with the 10mm fasteners. It is hard to get a good look at them but if you down load the photo and zoom in it gets a bit better. Bottom line they are excellent, they look good and other than some PITA drilling and tapping what's not to like?
I thought I had pics of the machining to add the 10 mm side bolts but I seem to have misplaced it. Here are two other pics of another upgrade that is definitely worth the effort. Main caps are a tight fit in OEM blocks they border on a press fit in the Hyland block. Because a custom build process involves so much assembly, disassembly and reassembly to check fit and clearances, I needed a good way to get the caps out of the block without removing the stud and wiggling them out. I built a home made cap puller form a diesel fuel injector puller that I modified to use a quarter inch or 5/16 inch stud to pull the cap out of the block.
Here is a pic of the caps in the mill after drilling and tapping for the stud puller;
And this is what the stud puller looks like in place;
The large hex portion sitting down by the main cap is a hammer slide that you use to pull the cap. I found the injector puller on eBay for about $15 if I recall and I put another $3 in steel into the head to finish the project. Cheap money to make a PITA job a breeze.
The drilling and threading of the side bolt holes was done cap by cap before moving on to the next cap. I wanted to dril, ream, and tap each hole without moving the work or the head on the mill. That would allow me to exactly place each 10 mm hole and thread in each cap.
The question about the primary chain selection is answered by the fact they are available over the counter at virtually all Auto Parts stores. You want to get the fine finish chain that is used on the 03/04 SVT Cobras. That chain is identified in the parts catalogs as being for the VIN Y vehicle code cars, which are by default the 03/04 SVT Cobras.
The best choice for the HD secondary chains is either Michael at L&M Engines or John at Accufab depending on which side of the country you are on. Currently the only source for the 9-Way secondary gears is Michael at L&M who has them custom made.
If I am not mistaken, Kirk, you have an '99 Cobra long block. If I you do, that is a special version of the Teksid block. That particular block uses the 9 mm side bolts like a WAP block and has the nice more robust square edged looking main caps like a WAP block. Check the width of those main caps, they just might be wide enough to put the 10 mm Accufab side bolts into. In fact if you decide to go the 10 mm side bolt route just ask John at Accufab if they can be installed into OEM Teksid main caps. He will know immediately and then you will too.