These install instructions were on Modular Headshop’s webpage years ago and were in my opinion the best write up that’s out there. This is a copy and paste from the Internet Wayback Machine. All credit goes to Modular Headshop
Degreeing cams on the modular motor is very important as it appears the stock cam gears are + or – 4 degrees from Ford. So you can have one cam 4 degrees advanced on one side and 4 degrees retarded on the other side. Too much cam advance is a good way to put the valve into the piston and too much cam retard is a good way to lose power.
You can use a welded lifter if desired for cam install centerline only as it is using the maximum lift of the cam for the test. The welded lifter will not work most times if you wanted to QC (Quality Control Test) the cams opening and closing points. To fully QC a cam’s opening and closing points you need good precision and between the base circle of the cam possibly varying (especially if the cam is over 0.550″ lift) and the install heights of the valve stems definitely varying a few thousandths, the adjustable lifter is needed.
You need to understand the basic cam installation first as can be found on this LINK before you will understand these instructions.
Accurate piston to valve (PTV) clearance check using this degree guide is shown on this LINK.
The following shows the tools we use for degreeing cams. Every person and shop will do it slightly different and with slightly different tools as there is no degree tool kit directly made for this motor.
Use this as a guide and find what you need locally.
We will comment on what is needed to be done at the various stages.
Degree wheel – we welded on a washer so it would center on the crank bolt better
Crank bolt and extra washers
Pointer for the degree wheel and holder – must be ultra rigid
Impact gun – makes this job much faster
Dial indicator with long extension and vice grip clamp
Piston TDC indicator
Adjustable lifter with small screwdriver to adjust it
Checking spring – needed if you want to know your piston to valve clearance
Adjustable wrench – helps turn crank for getting TDC perfect
Small hex key you see is for locking the timing chain tensioner
18MM wrench for turning crank back and forth easily
The 2 rachets and various sockets are for bolt installation and removal
First step is to find the TDC of the piston.
TDC = Top Dead Center, where the piston is at its highest point possible.
You can use any dial indicator for this, I like to use this specialty tool as it allows perfection every time. This is a very important step as the piston will “dwell” at the top slightly meaning it stays at TDC for more than 1 degree of crank rotation. Your first important job is to make sure you center the TDC in the middle of this dwell.
This indicator is showing – 0.013″ which is a typical TDC spec for the 4.6, the 5.4 will read -0.100″ or more typically. You must check this in line with the piston pin as done here as the piston will rock side to side the further away from the pin you get. If you get this step wrong everything else will be wrong and is a good reason to do this with the head removed.
Note – 2V are harder to do with the head always installed as the TDC indicator will have to go through the spark plug hole and thus is at a sharp angle to the piston top. The 4V is easier with the head on as the spark plug is centrally located and pointed straighter to the piston top.
Here is the adjustable wrench helping to move the crank to get the TDC centered. We are using it at the location of the oil pump flats.
And here we have installed the degree wheel and the crank pointer and found the “zero” degree point. It is very important that both of these parts are mounted very rigidly as any movement of them means you have to start all over. Our pointer is a flat piece of steel that came from a paint gun tool kit, and the bolt it is mounted to is a timing cover bolt with multiple nuts to lock it perfectly in place. Take your time here getting this perfect and triple check against the dial indicator on the piston top to ensure that your numbers repeat every time.
Note – make sure you have installed the crank gear and timing chain loosely as once the pointer is mounted it is impossible to get either of these on or off.
Here is another view of the degree wheel and pointer we used.
It is very important that neither of these items are allowed to move.
Install the cylinder head with the head gasket you plan to use or preferably a used one that has been compressed to the correct thickness. Stock head gaskets are ~0.036″ compressed. It seems the cam timing will retard 0.5 degrees negative for every ~0.008″ of thickness lost. So if you do this test without the head gasket you will be off by 2 degrees or so. Milling/decking the head and/or block will also retard the cam the same amount (0.5 degrees negative for every ~0.008″ of material removed)
Note – if you want to check PTV clearance you should install a lightweight spring onto the valve at this time in place of the stock valve spring.
Install the adjustable lifter and camshaft. You will want to degree the cam to the intake lobe of the piston that you set at TDC with the degree wheel.
Here you can see the jewelers screwdriver adjusting the lifter to take up all the slack between the rocker and the cam lobe.
Install the dial indicator that will measure the valve motion. Here we have a dial indicator with a long extension and the vice grip mounting system you can get from Harbor Freight.
Note – if you can find a valve spring retainer from a 95 and earlier modular they have a larger diameter and it is easier for the dial indicator to work from.
Another view of the dial indicator on the valve retainer and good view of the lightweight checking spring installed in place of a valve spring.
Install the timing components as you would a regular install. Instructions for this is found here. Then rotate the crank with a 18MM wrench and note the movement of the dial indicator on the valve. It should move smoothly without binding.
Rotate the crankshaft until the maximum valve opening is found with the dial indicator, then zero out the dial indicator at this maximum opening as shown below.
Rotate the crankshaft until the dial indicator reads 0.050″ as shown below, there will be 2 positions for this, once before reaching 0 and once after reaching 0. There will be a position before and a position after the 0 reading to find the 0.050″ points, you can turn the crankshaft backwards if needed but always go clockwise for the reading itself. Here is the first 0.050″ point for this particular camshaft:
And at the degree wheel we find 75 degrees:
The next 0.050″ position we find 141 at the degree wheel:
Now you take these 2 numbers and add them together:
141 + 75 = 216
Now you take this number and divide by 2:
216 / 2 = 108
Now we have verified that this particular cam is installed at a 108 intake centerline. You should repeat the rotation and degree notation 2 more times to ensure your accuracy, and once removing the head recheck that the degree wheel is still at 0 for TDC of the piston. If everything checks the same again then you know your cam is degreed properly. If you need to advance or retard the cam to get to the correct number you can either grind the keyway of the cam gear, get an adjustable cam gear, or get an adjustable crank gear from TFS like below:
Only issue with these crank gears is you should pin them together as the rear driver’s gear only sits on half the keyway in the crank (a design problem from Ford actually) as they are patterned after the original 2 piece gears Ford used up until 1999. Ford changed to a 1 piece design to stop the crank keyways from being damaged. To pin them together you need to drill them while they are installed on a crank and install a roll pin or other device to lock them together.
PTV – Piston to valve clearance check time
This is a good time to check the piston to valve clearance as shown on this link. With this setup you will get the most accurate piston to valve numbers possible and it will only take a couple minutes.
Repeat all of the above for the other head and cam and above all have patience as this is a tedious and time consuming job. Your engine will thank you if the cams are installed at the correct location.