Car Craft – October 2019

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The 5.3L was

run on the

dyno with these

DNA 1^3 ⁄ 4 -inch,

long-tube

headers feeding

a 2.5-inch

exhaust.

lobe-separation angle (LSA), the 5.3L

stick was hardly what you could con-

sider a powerhouse. By contrast, the

LS9 cam offered a 0.558-/0.552-lift

split, a 211-/230-degree duration split,

and (wide) 122.5-degree LSA. Though

designed for a positive-displacement

blower—in a larger motor, no less—the

GM cam offered a lot of performance

when stuffed into the smaller 5.3L.

Case in point, the cam swap increased

the engine speed where the motor

made peak power by almost 1,

rpm! On the smaller 5.3L, the LS9 cam

definitely wanted to rev.

If you perform a search for LS cams,

chances are the least-expensive cam

to come up (even new) will be the LS9.

GM still offers the popular cam near

Below: This early

(Gen 3) LM

was equipped

with a manual,

cable-operated

throttle-body.

Our junkyard LM7 was

the mildest of the

factory 5.3L offerings.

After plucking from the

local Pick-a-Part, we

performed an injector

upgrade. Because it

would eventually see

boost, we replaced the

stock injectors with a

set of 80-pounders.

14 CAR CRAFT OCTOBER 2019