1. Introduction
Talk to any cam grinder, engine builder, or racer and you’ll find overwhelming agreement that “degreeing-in” a camshaft is a vital step along the route to optimum engine performance. At first that may seem strange because “degreeing-in” a cam pertains to checking the accuracy with which it was manufactured. The purpose of degreeing a cam is to insure that the cam is phased correctly with the crankshaft, per the cam manufacturers’ specifications. You’re insuring that valve opening and closing events are in accordance with specifications, regardless of the cause. Actual valve opening and closing events are influenced not only by accuracy with which a cam was ground, but also keyway position in the crankshaft, crank timing sprocket, dowel pin hole position in the cam sprocket, and accumulation of machine tolerance also play a major role. It is the exception, rather than the rule, that a cam may be out of phase, but this should be established to insure an accurate performance baseline or point of tune.
2. Part Required
- Adjustable cam gears
- An accurate Degree Wheel for the crankshaft.
- A rigid pointer that can be attached firmly to the engine and indicate points on the Degree Wheel.
- Dial Indicator to accurately measure cam lift.
- Top Dead Center Piston Stop.
- 2 x modified hydraulic lash adjusters w/ 10mm shims or solid lifters.
- 2 x Light checking springs. (Used when checking piston to valve clearance)
Any cam degree kit will have everything excluding the cam gears and lifters.
3. Setting zero lash
Hyundai hydraulic lash adjuster (HLA)
Pry off the retaining cap to disassemble the HLA and discard the inner spring. You'll be shimming inside the lifter(refers to hydraulic lash adjuster herein after) to achieve the height needed for zero lash.
8 x 10 x 0.1 - 0.3mm shim set
Get an assortment of 10mm shims. 0.1mm(0.004") increment will be too large so be sure to pick up 0.05mm or 0.15mm. To get an estimate on how much shims you need, install the lifter, rocker arm, cam at it's base circle and measure the amount the plunger moves up before topping out and use that as a starting point.
check valve flipped and shimmed
Flip the inner check valve(middle part in picture) so it doesn't resist sliding down the body. If installed in it's normal direction it tends to bounce back up due to the trapped air compressing. You can push the check ball open as you would when bleeding the lifter so either way works. Stack the amount of shims you need, reassemble everything and torque the cam caps.
checking zero lash
Verify the rocker arms can't be twitched and if you can spin the plunger with a slight resistance then you have "zero lash". If not then you will need to add or remove the shims.
The preferred method is to use solid lifters(nut adjuster type). You can accurately adjust the lifters to have .001" preload, which can not be easily done using shims.
4. Install the timing belt
5. Mounting the degree wheel and pointer
degree wheel mounted over an ATI damper
The degree wheel is bidirectional having 180° from TDC in both directions. Mount the degree wheel so you have some means of turning the crank without interfering with the degree wheel.
mocking up the pointer
Rotate the crank until number one piston is at top dead center. This can be a rough guess. Next attach the pointer firmly to the block and adjust it so that it points to TDC on the degree wheel.
6. Finding the true top dead center (TDC)
Piston stop install
Turn the crankshaft opposite of engine rotation 15-20°(or to BDC). Install the TDC piston stop in the spark plug hole and screw in the inner piston stop until it touches the piston(or bottoms out). Continue to turn the engine in the same direction until the piston comes back up and touches the piston stop. Mark the degree wheel with a pen on the number the pointer is on. Turn the engine in the other direction, same as engine rotation, until the piston comes back up and touches the piston stop. Make a mark on the number the pointer is on.
Finding TDC
I have the stop points at 17.5° in one direction and 69° in the opposite direction. The total would be 86.5 degrees. This figure divided in half would be 43.25 degrees. Therefore 43.25 degrees from either of your stop points is true top dead center.
17.5° from TDC mark
69° from TDC mark
Adjusting the pointer
Now move the pointer to align with the 43.25 degree mark on the degree wheel(this is the only time you will be moving the pointer after initial setup) making sure that the piston is still against the stop. Now turn the engine in the opposite direction until the piston comes back up and touches the stop. The pointer should be aligned with the 43.25 degree mark on the other side of the TDC mark.
If this is correct, then you have found true top dead center and your pointer will point to the TDC mark on the degree wheel when cylinder #1 is at true TDC. It is best to repeat this to make sure that nothing has moved. Remove your piston stop and you are ready to properly degree your cam.
position pointer at 43.25°
pointer stops at 43.25° on the other side
Comparison after finding TDC
This is the before and after shot of the Eclipse cam gears alignment. The cam gears advanced(clockwise rotation) 1 crank degree with the true TDC and the cam gear marks no longer line up. .
TDC using the timing marks
after finding true TDC at the crank
7. Mounting the dial indicator
Make a metal base plate that you can bolt on the head for the dial indicator's magnetic base. Position the dial indicator mount so the tip will contact the retainer of the intake valve. You'll need to make a rigid extension (coat hanger works nicely) for the dial gauge since the retainers are deep within the head. Sand down the extension tip so you don't scratch everything it touches. It is important that the indicator plunger be parallel to the valve stem and located at a flat level on the spring retainer. Any variance in the angle of the indicator will introduce geometric errors into the lift readings. Be sure that the indicator is supported solid as any looseness will introduce MAJOR measurement errors.
8. Measuring timing events at .050" valve lift
This is for tutorial purpose only and are not the actual cam profile.
reference point at cam base circle
Rotate the crankshaft so that the camshaft base circle is over the rocker arm and set the dial indicator with .500" preload so it doesn't run out of travel. Rotate the crankshaft slightly and make sure the indicator reading does not change. Now you can set the indicator to read zero at this point. My cheapo gauge didn't have this function so I had to read the numbers and subtract. Picture showing indicator at the cam base circle.
.050" opening valve lift
Using the intake opening and closing at .050” cam lift, obtained from the information on your cam spec card, turn the engine in the normal direction of rotation. Watch the dial indicator. When it moves down .050”, stop rotating the engine.
5° BTDC @ .050" opening valve lift
Record the degree wheel number that the pointer is on. Then continue to rotate the engine in the same direction. Watch the dial indicator, it will change direction at maximum lobe lift. Record the max valve lift and degree wheel number. I'm showing 5° BTDC at .05" valve lift for the intake opening. Spec card shows it should be 10.5 BTDC so the intake cam is 5.5 degree retarded.
.050" closing valve lift
Continue to rotate the engine in the same direction until you reach .050” before closing. If you go past either of the .050” marks, back up at least .100” and rotate the engine in the normal direction again until you reach the .050” mark on the indicator.
39.5° ABDC @ .050" closing valve lift
Again record the degree wheel number that the pointer is on. Continue on to zero lift and verify that the dial indicator has returned to zero or it's original position. I'm showing 39.5° ABDC at .05" and the cam card says it should be 33.5° ABDC. So it's 6° retarded, close to the 5.5° at valve opening. Repeat this procedure on the exhaust cam.
The opening and closing figures should be within ±1 degree. If your figures are not within ±1 degree, go through the procedure again to check for possible error. If your opening and closing figures are still not correct you will need to move the cam in relation to the crankshaft in order to correct your opening and closing figures. This is where you make use of your cam gears. If the cam is opening early, the cam is too far advanced, and will need to be moved in the opposite direction of the cam rotation. If the cam is opening late, the cam is too far retarded, and will need to be moved in the direction of cam rotation. Repeat procedure 6-7 on the exhaust side. Once the cam is phased with the crank, per the manufacturer specs, then a baseline can be established. From that baseline of performance you can dial the cam exactly to your combination.
Centerline method of cam degree-in
Unless the manufacturer wants you to use this method don't bother. There are cam makers who list these values for reference only and does not represent true centerline as the lobes are often ground asymmetrical.
Adjusting the cam gears
The intake and exhaust cams are retarded 6 and 3 crank degrees compared to the cam spec sheet. HKS cam gear each mark on the scale represents 2 crank degrees so you would advance 3 and 1.5 degree at the cam gears.
9. Checking piston to valve clearance
When you install a high performance cam, it is possible that there may not be sufficient clearance between valves and pistons when near TDC on overlap. Even if they don’t touch when you rotate the crankshaft slowly by hand, they may hit and damage the engine at high revs due to slight “Floating” of the valves, stretch in the rods, deflection in the valve train, and other causes.
The easiest way of checking piston to valve clearance in an engine, with the cylinder heads installed, is to install a pair of light checking springs in place of the valve springs. These light checking springs will allow you to depress the valve easily at any time during the entire rotation of the engine, enabling you to measure the piston to valve clearance. While you're having to remove the springs it's a good time to measure the retainer to guide clearance along with coil bind, stem height etc.
With your degree wheel still mounted to the engine in correct TDC position, and the valves adjusted to zero lash, turn the engine in its normal direction of rotation until you come to 15 degrees before top dead center overlap on your degree wheel, then set the tip of the dial indicator on the exhaust valve spring retainer, in line with the movement of the valve. Preload the dial indicator to about the mid-point of travel, and set to zero. Depress the valve until the exhaust valve contacts the piston, make a note of the reading on the dial indicator, and record the clearance. Now, continue turning the engine in its normal direction two degrees at a time, checking and recording the clearance every two degrees until you reach top dead center on your degree wheel. Remember, since the valve will be moving, the dial indicator will not return to zero. You can either subtract the difference or reset the dial indicator back to zero each time before you make your clearance check.
Move the dial indicator to the intake retainer and start checking the intake piston to valve clearance the same way you checked the exhaust, except begin at top dead center and continue to 15 degrees after top dead center, turning the engine in its normal direction of rotation. The actual position of closest piston to valve clearance will depend on how far advanced or retarded your cam is. Remember, as you advance your cam you will lose intake piston to valve clearance and as you retard your cam you will lose exhaust piston to valve clearance. The recommend clearance is at least .080” between intake valves and pistons at all times, and at least .100” for exhaust valves, which expand more with heat. Add .030” to these figures if you have aluminum rods in the engine to allow for their expansion and stretch. With solid lifters you can get by with very tight intake clearance as minimum clearance is measured when the intake valve is chasing the piston down as it is opening. The exhaust on the other hand should still have plenty of clearance as the minimum clearance is measured when the valve is closing which may exhibit valve bounce under high rpm.
With a properly built head, you seldom need to go through all valves and checking one of each for the intake and exhaust is enough. If you are unsure or have a poorly machined cylinder head where valves have different height protruding at the deck, then you need to clay all the valve reliefs or measure from the lowest sitting valves. Claying can be an advantage since you can check all valves and the radial clearance as well. Although, I've never seen it being a problem on a DSM. Most aftermarket piston manufacturers cut the valve reliefs quite generously so unless you're running some outrageous duration cams you seldom have clearance problems but still checking the piston to valve clearance is highly recommended. Considering how old DSM's are and with so many shaved head/blocks with oversized valves, it's cheap insurance.
Crane cam P/N 435-0014
For this particular engine, opening & closing events were retarded 5 crank degrees for both the intake and exhaust. Minimum piston-to-valve clearance of .052" @ 8 ATDC for the intake and .097" @ 10 BTDC for the exhaust side installed with a Mitsubishi MLS gasket, JE 9.0-1cr and +1mm oversized valves. Advancing the cams to match the spec card will only give .030" clearance for the intake.