Camshaft Spec Help
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8th Gear
Joined: Mar 2024
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Camshaft Spec Help
Howdy all, I'm not sure I'm in the right place here but I am having some trouble deciphering what amount of advance is ground into the camshaft on my 351w. Truth be told its in a fox mustang haha, but I know you guys are pretty well versed when it comes to these motors.
Information on the Cam:
Comp Cams xe274h hydraulic flat tappet
110 LSA
230/236 duration at .050
.519/.523 valve lift
106 Intake Centerline
I'm assuming this has something to do with the intake centerline but I am unsure, any help on this matter would be greatly appreciated!
Information on the Cam:
Comp Cams xe274h hydraulic flat tappet
110 LSA
230/236 duration at .050
.519/.523 valve lift
106 Intake Centerline
I'm assuming this has something to do with the intake centerline but I am unsure, any help on this matter would be greatly appreciated!
Cargo Master
Joined: Oct 2020
Posts: 2,664
Likes: 779
The LSA of the camshaft is shown in camshaft degrees. It is the geometric angle of the centerlines of each lobe. The intake and exhaust centerlines are 110 degrees apart. If as in this case the intake centerline is 106 this means that the camshaft is advanced 4 degrees. If the lobe separation is 110 degrees and the cam is in on a 106 ICL then the exhaust is on 114.
How does this work?
With the cam ground on 110 lsa and in the engine 4 degrees advanced; The exhaust cam lobe reaches maximum lift and then the crankshaft rotates another 114 degrees to reach TDC. Then the crankshaft has to rotate another 106 degrees to get to where the intake lobe is at its maximum lift point/centerline.
How does this work?
With the cam ground on 110 lsa and in the engine 4 degrees advanced; The exhaust cam lobe reaches maximum lift and then the crankshaft rotates another 114 degrees to reach TDC. Then the crankshaft has to rotate another 106 degrees to get to where the intake lobe is at its maximum lift point/centerline.
Thread Starter
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8th Gear
Joined: Mar 2024
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Okay so if the lsa in this situation was 106 degrees instead, the ground in advance would be 0. Thank you sir!
Im assuming they list the intake centerline in CRANKSHAFT degrees as opposed to the lsa in CAMSHAFT degrees simply because this is checked with a degree wheel mounted to the crank?
Im assuming they list the intake centerline in CRANKSHAFT degrees as opposed to the lsa in CAMSHAFT degrees simply because this is checked with a degree wheel mounted to the crank?
Cargo Master
Joined: Oct 2020
Posts: 2,664
Likes: 779
That's right. If the LSA was 106 then the cam would be in the engine "straight up" with zero degrees of advance or retard.
LSA is in cam degrees mainly because that is what is used on the grinder. When I grind a cam I grind one side either the intake or the exhaust but normally the intake first. Using the index plate to go from cylinder to cylinder. Then I put in the amount of LSA on the index head of the grinder and then go back through the cylinders grinding the other lobe displaced by the LSA.
LSA is in cam degrees mainly because that is what is used on the grinder. When I grind a cam I grind one side either the intake or the exhaust but normally the intake first. Using the index plate to go from cylinder to cylinder. Then I put in the amount of LSA on the index head of the grinder and then go back through the cylinders grinding the other lobe displaced by the LSA.
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