Vortec L31 cylinder head

[[Category:Cylinder head]]

[[Category:Cylinder head]]

"The lope sound of the muscle car era is as obsolete as the tube radio. Those cams made more noise than power. If you want to run with the big dogs today, you've got to look for cams with a lot of lift for their duration and fairly long LSA's compared to the old stuff. Big problem today is the inexpensive flat tappet cam is as obsolete as the dodo bird. The flat tappet is very dependent upon low detergent, high zinc/phosphate (ZDDP) oils which except for expensive race only blends, are not to be found anymore. Today's oils are high on detergents and dispersants while low in zinc and phosphate additives. This is because the zincs and phosphates gunk up converters, costing OEM's money for warranty claims, so they've been outlawed. At the same time it is realized that a clean engine experiences less wear, therefore produces less pollution so with the help of 5 micron filters, the detergency is pumped way up. Now there are additives on the shelf to bump the zinc and phosphate levels up in ordinary off-the-shelf oils but these oils are high detergency oils that scrub off the zinc and phosphate coatings so pouring in more from an additive bottle has been proving to be somewhat ineffective. The OEMs went to roller cams in the period of 1985 to 1995 in anticipation of the change in oil chemistry resulting in wear problems between the lobes and flat tappet lifters. In my opinion the day of the flat tappet cam in the hands of the average hot rodder on the street are over. The loss of a flat tappet cam and the secondary damage from all the metal shavings circulating with the oil is so high that it just isn't worth the front end costs that were thought to be saved. So if you're building on a Vortec block from 1995 or later it is at least provisioned for a roller cam if a 95 and from 96 up it has a roller cam. The factory lifters can be used with a more aggressive roller as can the push rods and rockers. The Comp XR264HR has a good midrange with an rolling idle, the XR270HR pushes the power band up the rev range and has a solid stagger to the idle it needs a high stall converter and 3.50 or numerically-higher rear gears.

"The lope sound of the muscle car era is as obsolete as the tube radio. Those cams made more noise than power. If you want to run with the big dogs today, you've got to look for cams with a lot of lift for their duration and fairly long LSA's compared to the old stuff. Big problem today is the inexpensive flat tappet cam is as obsolete as the dodo bird. The flat tappet is very dependent upon low detergent, high zinc/phosphate (ZDDP) oils which except for expensive race only blends, are not to be found anymore. Today's oils are high on detergents and dispersants while low in zinc and phosphate additives. This is because the zincs and phosphates gunk up converters, costing OEM's money for warranty claims, so they've been outlawed. At the same time it is realized that a clean engine experiences less wear, therefore produces less pollution so with the help of 5 micron filters, the detergency is pumped way up. Now there are additives on the shelf to bump the zinc and phosphate levels up in ordinary off-the-shelf oils but these oils are high detergency oils that scrub off the zinc and phosphate coatings so pouring in more from an additive bottle has been proving to be somewhat ineffective. The OEMs went to roller cams in the period of 1985 to 1995 in anticipation of the change in oil chemistry resulting in wear problems between the lobes and flat tappet lifters. In my opinion the day of the flat tappet cam in the hands of the average hot rodder on the street are over. The loss of a flat tappet cam and the secondary damage from all the metal shavings circulating with the oil is so high that it just isn't worth the front end costs that were thought to be saved. So if you're building on a Vortec block from 1995 or later it is at least provisioned for a roller cam if a 95 and from 96 up it has a roller cam. The factory lifters can be used with a more aggressive roller as can the push rods and rockers. The Comp XR264HR has a good midrange with an rolling idle, the XR270HR pushes the power band up the rev range and has a solid stagger to the idle it needs a high stall converter and 3.50 or numerically-higher rear gears.