Camshaft

[jacob54904]

i am trying to figure out what type of cam to put in my 350, everything is stock but i will be putting on vortec heads and vortec intake. please give me some input on what durations and lifts will work for me.

[jveik]

well, the first thing to keep in mind is that stock vortec heads dont allow for very high valve lift, i think somewhere in the upper 400's in thousandths of an inch. if you are using a stock torque converter, go no bigger than a comp cams 268 extreme energy cam. this actually may have more lift than the heads can accomodate.

one thing to look into is scoggin dickey, which sells vortec heads with modifications to accept more lift. i think they have some that accept up to
.525 lift if i remember right. the lift your heads are limited to is not the smaller number of the actual lobes, it is that combined with the rocker ratio, so keep in mind that if you go over a 1.5 to 1 rocker ratio, the lift will be much higher at the valve.

for example, a cam with lobe lift of .330 will have valve lift of .495 with 1.5 rockers and if you put in 1.6 rockers it will raise up to .528 which is another
.033 more lift than the smaller rockers.

[Blue Bowtie]

Lift is really only one part of the formula. There are other factors in camhaft design and lobe profile which may affect your outcome even more. It's going to help to know what vehicle this engine will power, and for what purpose. If the 350 is going to sit between the gutted out fenders of a gutted out F-car weighing 2400 pounds, and is routing through a 4.88 gear set, the camshaft design might be one way. If the 350 is going to sit in front of a 5500 pound G20 cargo van with 2.56 gears and pull a trailer, the camshaft design would be significantly different, all at the same lift numbers.

What are you doing with the engine, anyway?

[fuzzypuppy]

Bowtie is correct , I posted about this in another post from jacob, I have the same truck and have done alot of research on this because I have started these same modifications to my truck, 5.7 TBI.
The TBI engines are very limited in cam grind, I went with the hottest cam I could while still keeping the vacume up, it's what the factory tech recomended and still I have a bit of "idle search" problem.
The stock vortec heads are limited as well but getting them worked would be useless since the computer ie vacume is the most limiting factor and will only allow a small amount of lift and duration added over a stock cam unless other modifications are made.
I have the exact grind in my paperwork somewhere but I got the Edelbrock camkit 2102, only because it was cheaper than the comp cam with the exact same grind.
The addition of the vortec heads, a little hotter cam along with some other bolt on's would be an improvement, but laying out exactly what you want from your truck and what it's main use will be, then buying the equipment to reach this goal is the best idea.
The equipment you'll need to go for a rock crawler is going to be very different than if you want a good highway puller.
Post back with more info and i'm sure you'll get some good ideas.