Originally Posted by
Roadknee
Theres nothing wrong with 383 TBI. It will build about 40 more ft-lbs than a comparable 355. I considered one for my 1995 K1500. I'm sticking with the 350 due to concerns of the 4L60e holding up in a heavy truck.
If you're truly after low end torque, I'd look into smaller heads and cam. What you've selected would pull strong to 6k, but give up a lot below 2,500 rpm, particularly at part throttle. I think it would be pretty weak on the highway in OD with the torque converter locked.
For heads, I'd recommend what BLG or Brian are running, or a set of OEM vortecs. I think BLG's cam is a winner for a truck, and will pull strong to 5,200 or so while still making good torque. The GM cam in Brians motor is a good one too. It runs better than you would think for its size. It would build more bottom end than BLG's, but fall off about 400 rpm sooner. For a truck with OD, I'd recommend no more than 260 duration at 0.006" and 206 at 0.050 on the intake. A little added exhaust duration will help extend the HP peak, but will hurt low speed torque and part throttle fuel economy.
I've helped 355chev on this site tune the vortec 355 tbi in his 1995 K1500. It's running vortec heads, 10:1 compression, bored TBI, 5.7 injectors, 28 psi, performer manifold, headers, a 260 Comp Cams xtreme 4x4 hydraulic roller with 210 @ 0.050 intake duration. This cam has very aggressive lobes with over 130° @ 0.200". It pulls really strong, making about 320-330 hp at 5,200 rpm. Part throttle torque is a little weak requiring we delay locking the torque converter till 60 mph.