- 2,020
- 24
- Nov 10, 2002
-
Raleigh,
North_Carolina
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???
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???