Hi all. I'm looking to replace the dead 350 in my old 87 Silverado. Needs new piston rings. I want to use a 5.3L LS engine from a newer truck, but I figured why not add a little spice to it first. However, there are some limitations I want to abide by. They are:
1. Can't harm the factory fuel mileage very much.
2. Can't harm engine longevity. I want the engine to last 200k miles or whatever the 5.3L is typically known for.
3. Can't harm the factory road manners. I want the factory idle, so no rough cam. No obnoxious racket or bad smells.
This is pretty easy
What you're describing is camshaft with minimal overlap and with lobe profiles that are easy on the valvetrain.
Intake lobe - 208-212 degree (@.050)
Exhaust lobe - 214-218 degree range (@.050)
LSA above 110
For shelf cams I'd suggest:
Comp Cams XR265HR (212/218 112/116 .522/.529) or BTR Stage 2 Truck Cam V2 - BTR31218110 (212/218 111/111 .553"/.553")
Valve events for the Comp XR265HR:
Intake Opens BTDC: -6
Intake Closes ABDC: 38
Exhaust Opens BBDC: 45
Exhaust Closes ATDC: -7
Lobe Separation Angle (cam degrees): 114
Valve events for BTR Stage 2 Truck Cam:
Intake Opens BTDC: -5
Intake Closes ABDC: 37
Exhaust Opens BBDC: 40
Exhaust Closes ATDC: -2
Lobe Separation Angle (cam degrees): 111
Versus the BTR cam the Comp will have a slightly softer low end, a slightly stronger top end and but less idle chop
The BTR cam will provide sub-2500 rpm HP/Torque on par with the stock truck cam but will run away after
Both cams provide relatively tame idle characteristics, excellent low-end torque and huge mid-range/top end improvement (40+ HP at peak) versus the stock cam.
You could also install the BTR cam on a 112 or 113 intake centerline to tame the idle even more for a slight trade-off in sub-2500 HP/TQ.
Pair up with a TBSS intake, hardened pushrod/spring kit, and a quiet yet high flow exhaust and have fun.