Need help with SOHC Degreeing

[Doug99RS]

So I'm dialing in a SOHC and I'm currently under the impression that the cam (aftermarket) may be out by 9 cam degrees from where it was installed using an AEM cam gear. Here's a link to a page I've been using to do this and I've also watched the video that came with the degree kit from Comp Cams. http://www.escortfocus.com/html/how_to_degree_a_camshaft.html
Here's the cam spec sheet:

Crane p/n 158-0012
Grind # CHR-250-2sr-8
Lift:
intake @ Cam 0.2304------------@ valve 0.355-------------Rocker Arm Ratio
Exhaust @ Cam 0.2067------------@ Valve 0.315-------------In 1.54 / Ex 1.52

Cam Timing---------------Opens-------------------------Closes--------------------Duration
@ 0.006--------------Intake 10.0 deg BTDC-------60.0 Deg ABDC---------------250.00
Valve Lift-------------Exhaust 54.0 deg BBDC-----16.0 Deg ATDC---------------250.00

Cam Timing------------Opens------------------Closes----------Max Lift----------Duration
@0.050---------Intake (9.0) Deg ATDC----33.0 Deg ABDC--107 Deg ATDC---204.0 Deg
----------------Exhaust 29.0 Deg BBDC----(9.0) Deg BTDC--109 Deg BTDC---200.00 Deg

Here's the process I used and the results:
Locating Intake lobe Centerline- Divide duration by 2 (250/2=125) subtract opening number (10) which gives me 115 degrees
Locating Exhaust Lobe Centerline- Divide Duration by 2 (250/2= 125) subtract closing number (16.0) which gives me 109 degrees.
Locating lobe center spread- Add intake and exhaust (115 + 109= 224) and divide by 2 and my lobe center spread is 112 degrees.

Locating TDC- Install Degree wheel on crank, install pointer for Degree wheel, install piston stop, rotate piston slowly until it contacts piston stop and turn degree wheel to zero. Rotate crank backwards until piston stop is contacted again and note degree (62 degrees). Divide degrees by 2 and that should yeild TDC (31 degrees). Remove piston stop.

Locating Centerline of Cam- Install Dial indicator exactly where roller meets cam and at the same angle the roller moves. Rotate the engine until dial indicator travel is maxed out. Zero Dial at top of travel. Turn engine backwards just PAST 0.050" then rotate engine in proper direction (to apply proper tension) back to 0.050". Mark Degree wheel (194 degrees). Continue rotating crank past top of cam lobe to 0.050" and note degree reading (120 degrees). Add first and second numbers (194+120=314) and divide by two (157) which will give me the Cam Centerline.

Here's where I get a little lost/confused/concerned. Where I ended up was within 9 cam degrees of the cam being full up. I.E., I moved the cam 9 degrees of the cam and it was full open. But that's 18 crank degrees and it's an interference engine so of course we don't want to buy a bunch of valves.
Help???

 

[IHeartTurbo]

I don't understand why they are telling you to do centerlines like that. The way I learned to do it was this:


Intake lobe centerline:
Put the dial indicator on like you mentioned. Go to max lift. Rotate counterclockwise past .050" then clockwise to .050" Record reading on degree wheel. Now rotate clockwise past max lift to .050" Record reading. Add both numbers and divide by two.

Exhaust lobe centerline:
Do the same as intake lobe centerline but on the exhaust obviously.

Cam centerline:
Add your intake lobe centerline to your exhaust lobe centerline and divide by 2.

Two find out if your cam is ground straight up, advanced, or retarded:
Compare the cam centerline to intake lobe centerline. If the intake lobe centerline is less than the cam centerline, you are that many degrees advanced. If they are the same, the cam is straight up. If the intake lobe centerline is more than the cam centerline, you are that many degrees retarded.

 

[Big Woo]

Finding TDC
If you use a piston stop, then it must be stooping the piston before it reached TDC. So before installing the piston stop, turn the motor over until the piston is at TDC, at this point just a visual reference is needed. Set the pointer to line up with the TDC mark on the degree wheel. Then rotate the motor to bring the piston down and install the piston stop. Rotate the motor clockwise gently until the piston hits the stop. Notate the number of degrees indicated by the pointer, then rotate the motor counter clockwise until the piston again make contact with the piston stop, and again notate the number of degrees indicated. Compare your two numbers and find the difference between them. For example when rotating clockwise 32 degrees, and counter clockwise 28. Without rotating the motor adjust the pointer to the 30 degree mark, and then rotate back in the opposite direction, and verify that you get the same number of degrees. You may need to do this a few times to ensure accuracy.
Of note here is to make certain that your crank attachment point for your degree wheel in solid, and that your means of rotating the motor does not alter the degree wheels position when rotating in either direction. This can sometime happen if you are using the front center crank bolt to rotate the motor, when you turn it counter clockwise.

Don't read to much into the cam specification card, when it says 8 degrees BTDC it is specifying crankshaft degrees. So if your numbers say it is opening at 5 degrees BTDC and the cam card says it should open at 9 degree BTDC then the cam is 4 degree retarded, and you will need to advance it 4 degrees to get it to its as ground straight up position.

Also try moving further past your .050 mark by another .050 or so and then creep back to the .050 mark in the proper direction.

When setting your dial indicator make sure that it is moving relative to the VALVE, as you will notice on your cam card that it specifies the rocker ratio, and this does factor into the specified values for the intake and exhaust valve opening and closing times.

For example the information provide on your cam card states that the intake valve should open at 9 degrees ATDC at .050 of lift, this lift is measured at the valve, and not "NOT" the cam lobe. it goes on to state that the intake rocker ratio is 1.54:1 so if you are measuring at the rocker/cam contact point then the actual valve lift will be .077 or .050 x 1.54.

 

[Doug99RS]

So from the sounds of things at this point where I am at I shouldn't even be crunching numbers yet. It would appear that I'm not even set up properly and that I should move the location of my dial indicator.
Should I:
A: Put the rocker arms/lifter assemblies back on at least for cylinder 1 and put the dial indicator on the top of the rocker/lifter arm (I think no because of lifter squish since I don't have a solid lifter available)
B: Put the rocker arms/lifter assemblies back in and measure off of the valve spring retainer in the same direction that the valve is installed and moves?
Thanks for the feedback.
Doug

 

[Doug99RS]

After a couple of weeks of procrastinating and running the bank account dry (drove the gas guzzler Ram for 2 weeks) I finally cranked the car up tonight.

I found the Exhaust CL to be at 107.5 degrees and the Intake CL to be at 104.5 degrees. Lobe Center spread was 106 meaning the cam was advanced by 1.5 degrees. After starting this post I still think I might have overcompensated. I retarded the cam gear 3 notches with each notch being worth 2 degrees of the crank. So... I should have only retarded the timing 1 notch right? Well, it runs, no bent valves and I fixed a couple of oil leaks in the process. New rotors, wheels and tires went on so all is not lost. Maybe everyone is right, take it to a dyno. The days of dialing in a cam first are gone.

Thanks for the help,
Doug