HELP.......It has been to long since I degreed in a cam.....I am installing an X303 in my 5.0............can someone walk me through the steps and how to's on reading the degree wheel.................where can I get the proper specs etc. the can did not come with the usual, or at least as I am accustomed to, cam spec card.
cam degreeing
- Thread starter 1965kgt
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Michael Yount
Mustang Master
Without the cam card data, you've got a problem -- so you need to get that. Once you do it will tell you at what point (degrees before or after TDC) the intake valve should be open when the cam lift on that valve is at .050". That's where you want to install the cam - and you'll need an indexed gear set to do it - should have multiple slots on the crank gear allowing you to move it in 2 degree increments from 8 degrees advanced to 8 degrees retarded.
You'll need the degree wheel, a dial indicator and stand (at least 1" stroke), and, if the heads are on, a positive stop for the piston. I made mine out of an old spark plug - bust out the internals, grind off the ground tip, screw a bolt in the end of it, cut the head off the bolt so 1.5" or so can protrude into the cylinder when this is screwed into the #1 spark plug hole.
First, install the cam the regular way - dot to dot. Once that's done, put your degree wheel on the crank, make a pointer out of an old coat hanger - sharpen the end for more accuracy. If heads are off, set up your dial indicator over the #1 piston. Take a degree wheel reading with piston say .100" in the hole, rotate the piston up and over the top back down to .100" in the hole and take another reading there. TDC is halfway between those readings. Make a note of what reading on the wheel is TDC - or reposition your pointer to 0TDC. Don't try to move the degree wheel around as it usually moves the crank some minor amount. The same procedure works with the positive stop if the heads are on. Put the piston down in the stroke; screw the stop in, rotate the engine one way til it contacts the stop - record the degree wheel. Rotate it the other way until it contacts the stop - record the degree wheel. Remove the stop - tdc is halfway between the readings. DO NOT try to use the dial indicator to determine when the piston stops moving at the top with the head off - the crank can move 3-5 degrees with the piston at the top - that'll throw your measurements off.
Once you know where tdc is, set the dial indicator up on the head so you can measure lift on the tip of the #1 intake lobe - use the pushrod to make it easier. Be sure your indicator is parallel with the motion of the pushrod. Rotate the engine around until you're at .050" lift on the intake valve - opening. See where you are on the degree wheel relative to tdc, and compare that number to the cam card data.
So, let's say the X cam calls for the intake lobe to be at .050" lift 5 degrees BTDC (making things up for an example). And let's say you measured, and installing dot to dot you're between 4 and 6 degrees BTDC at .050" -- then put your stuff away, you're done. On the other hand, suppose you measure and you're at 9 degrees BTDC (it CAN be that far off on a dot to dot install - that's why you're degreeing). That means the cam is opening the the valve 4 degrees too soon - meaning you're actually 4 degrees advanced from the cam card data. To get it to open 4 degrees later at 5 BTDC, you need to retard the cam timing by 4 degrees. So you'd pull off the indexed timing set, and select the "4R" slot, reinstall, and remeasure -- you should now read 5 btdc at .050". If upon your dot to dot install/measurement it read 1 degree BTDC, you'd be 4 degrees off in the other direction, and you'd want to ADVANCE the cam 4 degrees to move it to the cam card spec (use the "4A" slot). Capice?
While there, and once the cam is set properly, you should check peak lift with dial indicator, intake closing at .050" and exhaust open/close at .050" -- you can also check the advertised opening/closing numbers. These are usually at .006" lift unless the cam card specifies otherwise.
You should also measure p to v clearance once the cam is installed properly. You need minimums of .080" intake, and .100" exhaust. Hope that helps.
You'll need the degree wheel, a dial indicator and stand (at least 1" stroke), and, if the heads are on, a positive stop for the piston. I made mine out of an old spark plug - bust out the internals, grind off the ground tip, screw a bolt in the end of it, cut the head off the bolt so 1.5" or so can protrude into the cylinder when this is screwed into the #1 spark plug hole.
First, install the cam the regular way - dot to dot. Once that's done, put your degree wheel on the crank, make a pointer out of an old coat hanger - sharpen the end for more accuracy. If heads are off, set up your dial indicator over the #1 piston. Take a degree wheel reading with piston say .100" in the hole, rotate the piston up and over the top back down to .100" in the hole and take another reading there. TDC is halfway between those readings. Make a note of what reading on the wheel is TDC - or reposition your pointer to 0TDC. Don't try to move the degree wheel around as it usually moves the crank some minor amount. The same procedure works with the positive stop if the heads are on. Put the piston down in the stroke; screw the stop in, rotate the engine one way til it contacts the stop - record the degree wheel. Rotate it the other way until it contacts the stop - record the degree wheel. Remove the stop - tdc is halfway between the readings. DO NOT try to use the dial indicator to determine when the piston stops moving at the top with the head off - the crank can move 3-5 degrees with the piston at the top - that'll throw your measurements off.
Once you know where tdc is, set the dial indicator up on the head so you can measure lift on the tip of the #1 intake lobe - use the pushrod to make it easier. Be sure your indicator is parallel with the motion of the pushrod. Rotate the engine around until you're at .050" lift on the intake valve - opening. See where you are on the degree wheel relative to tdc, and compare that number to the cam card data.
So, let's say the X cam calls for the intake lobe to be at .050" lift 5 degrees BTDC (making things up for an example). And let's say you measured, and installing dot to dot you're between 4 and 6 degrees BTDC at .050" -- then put your stuff away, you're done. On the other hand, suppose you measure and you're at 9 degrees BTDC (it CAN be that far off on a dot to dot install - that's why you're degreeing). That means the cam is opening the the valve 4 degrees too soon - meaning you're actually 4 degrees advanced from the cam card data. To get it to open 4 degrees later at 5 BTDC, you need to retard the cam timing by 4 degrees. So you'd pull off the indexed timing set, and select the "4R" slot, reinstall, and remeasure -- you should now read 5 btdc at .050". If upon your dot to dot install/measurement it read 1 degree BTDC, you'd be 4 degrees off in the other direction, and you'd want to ADVANCE the cam 4 degrees to move it to the cam card spec (use the "4A" slot). Capice?
While there, and once the cam is set properly, you should check peak lift with dial indicator, intake closing at .050" and exhaust open/close at .050" -- you can also check the advertised opening/closing numbers. These are usually at .006" lift unless the cam card specifies otherwise.
You should also measure p to v clearance once the cam is installed properly. You need minimums of .080" intake, and .100" exhaust. Hope that helps.
thumper460
Founding Member
Mike's the man... 
!!
Of all the FMS cams I have degreed and checked, they were on the advertised specs.. : B- 107 ICL, E- 110, F-109, ect... let us know what you find. cool??
Just me...........................
Thumper
!!Of all the FMS cams I have degreed and checked, they were on the advertised specs.. : B- 107 ICL, E- 110, F-109, ect... let us know what you find. cool??
Just me...........................
Thumper
Michael Yount
Mustang Master
....and, to Thumper's point, in addition to the grind of the cam, there's placement of the hole in the cam gear, placement of the 'dots' on both gears, placement of the keyway in the crank, placement of any of the slots in the crank gear, how closely to perfect the lifter bores align with the camshaft - all of which can be off, in addition to the cam grind. Stack all the tiny tolerances one way, and you can be 4 to 6 degrees off on a dot to dot install.
