Ok all I am building a Vortec 350 for my tow rig. I have a 1996 Chevy 3/4 ton HD truck. It has the 4L80 w/shift kit and a 14 bolt rear with posi. I have already made a set of custom long tube headers. (shorties are junk) I have a throttle body spacer, underdrive pulleys, took out the restrictor plate on the throttle butterfly. The bottom end is stock all the way to the heads. I have a cam that is about to go in. It specs out at duration 208/221. Lift is .474/.510". Seperation is 112. I am hoping to have 300 reliable horses an maybe 350 Ft/lbs. torque.

My question is that is this cam a good Idea to use and Would it benefit me to put bigger valves in the heads. All the aftermarket vortec heads I've seen run the stock sized valves! I know my motor doesn't breath much fire but would valves give me much bang for the buck. I am also looking for a pair of Roller rockers to put in.

Please let me know what you got and if you have any input it would be appreciated. I love my chevy and I know these Vortec 350's are great motors! But there is always room for improvement!!!... Right?  

Bigger valves will only benifit most street engines like yours around 6000 RPM or higher. This will not help towing at all and the bigger valves can in some cases hurt your torque.  

Big valves are for rpm's,simple as that.The flow of a 2.02 intake does nothing for low end-midrange power,as 69camaro1 stated.But Chev truck heads had 2.02's in some cases if you run steep gears back in the 3 spd auto days,so I cant say it would cause losses on the bottom end,just no gains under 6,000.The cam that big will KILL your grunt,unless you degree it so far to lose top end power.Off stock very little cam is needed for towing power were you want it.Even with a roller,Id think that 1's a lot.I recomend to call Crane Cams tech line.They can definatly tell you what you need to know.  

So what else do you guys suggest? The engine runs great and has less than 15% leakdown in all cylinders so I want to put off any real internal work. What are these chevy's good for as far as valve lift??

I think my goals are reasonable. I get on average 15 MPG with my extended cab long box truck. It tips the scales at 5600 pounds. Which is prety good I think. I appreciate the imput and can always use more!  

I agree that your cam may be a bit long on duration for a towing rig. You want as much low end torque as possible for towing; and a flat torque curve as well. Your lift isn't a problem except with your stock vortec heads. In order to have a cam with a lift bigger than .460 you have to get them modified. Grinding down the tall valve guides. GM performance dealers like Scoggin-Dickey in TX will do it for you when you buy new ones. Any competent machine shop can as well.

Good luck with it. Don't take too long working on it. You want your truck to enjoy the summer.  

The only thing I don't understand about that cam is the huge exhaust profile in relation to the intake. It has plenty of lift on both sides but .470" lift is different than .500+. Over a half inch of lift can usually require some serious modifications for springs whereas stock or near-stock sized springs are commonly maxed at the .470" mark. 208° @ .050" is no problem (especially on a 112° separation) but that large exhaust adds to overlap and just seems a little excessive to me, who did you say makes this grind? I say look for a dual-pattern cam with 5-6­° more exhaust duration than intake duration, not 13°!, and near the same lift on both sides.