Just found out I'm cam illiterate!

Unit 5302 · 05-23-2002, 07:13 PM

Your combo isn't setup for a "big boy" cam. You have a modified 302 that will make max power around 5500-6000rpm with those heads at best. Adding a monster cam is for strokers, or higher rpm engines.

Lift is how high the valve lifts off the seat in the head. Take a look at say, an E303.

.498/.498 220*/220*@.050 282*/282* LSA 110* LCA 107*/117*

.498/.498 lift. That means the maximum valve lift is .498" including the rockers multiplication effect. Standard rockers have a 1.6:1 ratio, meaning it multiplies the true cam lobe lift by 1.6. That means the camshaft's actual profile is smaller than the advertised lift. An E303 cam itself has a lobe lift of .31125"

220*/220*@.050 That means the duration at .050" lift (which is the industry standard measurement) is 220* So for 220* of the crankshaft the intake valve is at better or equal to .050." Same for the exhaust. Having the same duration for intake and exhaust just means the cam isn't favoring either the exhaust flow, or the intake flow. It's important to note duration is based on crankshaft rotation, not camshaft rotation. A crankshaft will rotate 720* per each camshaft rotation.

282*/282* is advertised duration. From the time the cam begins to lift at all, it's lifting 282.* Different manufacturers measure this at different lifts. .004-.006 or so.

LSA is Lobe Seperation angle. It's how far apart the lobes between the center of the intake and exhaust lobe are spread. The wider the spread, the higher your engine vacuum will be, and it's also important for low end power. The closer they are, the less vacuum you'll have, and you'll be trading lower rpm drivability for higher rpm power. Anything with less than a 110* LSA isn't going to be a good low rpm cam. Most street 5.0 cams are somewhere between 110*-114*.

LCA is Lobe Centerline angle. LCA is measured at TDC and by the peak of the lobe lift in relation to TDC. Since lobe lift is usually at the center of the lobe, LSA and LCA are normally the same. You can change cam timing to be more aggressive or less aggressive by installing the cam retarded or advanced. If you change the cam timing, you'll change the charachteristics of the cam somwhat. Lobe Centerline angle affects the camshafts performance profile much the same as LSA does.

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05-23-2002, 07:13 PM	#2
Unit 5302 Registered Member Join Date: May 1999 Posts: 5,246	Your combo isn't setup for a "big boy" cam. You have a modified 302 that will make max power around 5500-6000rpm with those heads at best. Adding a monster cam is for strokers, or higher rpm engines. Lift is how high the valve lifts off the seat in the head. Take a look at say, an E303. .498/.498 220/220@.050 282/282 LSA 110* LCA 107/117 .498/.498 lift. That means the maximum valve lift is .498" including the rockers multiplication effect. Standard rockers have a 1.6:1 ratio, meaning it multiplies the true cam lobe lift by 1.6. That means the camshaft's actual profile is smaller than the advertised lift. An E303 cam itself has a lobe lift of .31125" 220/220@.050 That means the duration at .050" lift (which is the industry standard measurement) is 220* So for 220* of the crankshaft the intake valve is at better or equal to .050." Same for the exhaust. Having the same duration for intake and exhaust just means the cam isn't favoring either the exhaust flow, or the intake flow. It's important to note duration is based on crankshaft rotation, not camshaft rotation. A crankshaft will rotate 720* per each camshaft rotation. 282/282 is advertised duration. From the time the cam begins to lift at all, it's lifting 282.* Different manufacturers measure this at different lifts. .004-.006 or so. LSA is Lobe Seperation angle. It's how far apart the lobes between the center of the intake and exhaust lobe are spread. The wider the spread, the higher your engine vacuum will be, and it's also important for low end power. The closer they are, the less vacuum you'll have, and you'll be trading lower rpm drivability for higher rpm power. Anything with less than a 110* LSA isn't going to be a good low rpm cam. Most street 5.0 cams are somewhere between 110-114. LCA is Lobe Centerline angle. LCA is measured at TDC and by the peak of the lobe lift in relation to TDC. Since lobe lift is usually at the center of the lobe, LSA and LCA are normally the same. You can change cam timing to be more aggressive or less aggressive by installing the cam retarded or advanced. If you change the cam timing, you'll change the charachteristics of the cam somwhat. Lobe Centerline angle affects the camshafts performance profile much the same as LSA does.