im in the process of rebuilding a 5.3 to pump in my trail truck. I need a cam thatll produce most of its power off idle and low in the RPM's. also looking for a cam to work with a 2000-2500 stall. what would be my best combo?

 

What year is the 5.3?

to reach these goals you want failry short duration and a tight LSA to jack up dynamic compression and be pretty close to having valve overlap to help keep air moving.

if its a newer 5.3 with the 799 heads that may look like this : 212/218 110+2

Thats assuming you have headers. Without headers that'll change. maybe 210/218 110 with no advance.

You'll also want a fairly aggressive intake lobe to keep the .006 lift numbers as small as you can... again for dynamic compression.

 

Its a 01' 5.3. Its a trail truck so hill climbing, rock climbing and low rpm power is really needed. Not a mud bogger. So short duration with a low LSA is what I need? What about lift? I can't seem to find a set of long tube headers for a 4wd 73-87 K5 blazer. So I may just stick with the factory manifolds

 

with factory manifolds you want a little less overlap, and you want it centered over the intake stroke. You want the exhaust valve open as late as possible to push out as much exhaust as possible, and you want the intake to open a little later so that it doesn't open to more pressure in the cylinder than the velocity of air trying to go in... it messes with your intake flow. Its why the factory cams have such late intake valve events.

When you say low RPM power... you mean part throttle power more so than chopping the throttle... that's where the game changes. In that case you need a little LSA in the cam. The tighter LSA hurts real bottom end, but it makes the meaty power come on sooner. For low RPM part throttle you need everything to be a little more smooth.

Look into the vinci 'butt kicker'. IF you spend more time at decent throttle but still low RPM then the 'chopper' will be better.

LS TRUCK CAMSHAFT

 

Awesome find on those cams. Those are about what I'm looking for. So would some shorty headers do any good? That's about all I would be able to run. Or would stock manifolds work just as good?

 

Also talk to Roger. His truck cams tend to have a little more advance ground into them than the car cams... That's great if you have headers... but with the stock manifolds it could do more harm than good.

For instance with your manifolds a 114+2 would be better than a 114+4. Thats a very general statement... but its somethign worth asking him.

And from what i've seen the shorty headers dont do anything... but ive never had any first hand experience with them. LS manifolds are a hell of a lot better than the old school log style that used to come on the SBC.

 

, i do have a set of 2001 f body manifolds. Idk much about shorty headers, but if they dont work any better then a factory LS manifold, I could weld up the egr ports and use them, if they would do better then a truck manifold?

 

It sucks they dont make a set of long tubes for a 4wd square body Chevy