Car Craft – October 2019

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LS9 cam Stock LM7 cam

$100 Cam Swap

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ON THE DYNO

What can you get for $100 these days? How about an extra 60 hp from a cam

swap? For this test, we upgraded the stock LM7 cam and springs with an LS

cam and LS3 valvesprings. The used takeoffs are available from a variety of

sources; we got both of ours for an even $100 off of eBay ($70 for the cam

and $30 for the springs). Equipped with the stock cam, the well-used junkyard

5.3L produced 342 hp at 5,300 rpm and 373 lb-ft of torque at 3,900 rpm.

After installation of the LS9 cam and LS3 springs, the power output jumped to

402 hp at 6,200 rpm and 379 lb-ft of torque at 4,900 rpm.

Below: After swapping out the valvesprings,

we turned our attention to the camshaft.

Off came the stock damper and front cover

to provide access to the timing chain.

With our

LS3 springs

in place, we

reinstalled

the stock

pushrods and

rocker arms.

Left: Once we removed

the force holding the

springs, the installation was

complete. Now all we had to

do was repeat the procedure

with the remainder of the

stock truck springs.

16 CAR CRAFT OCTOBER 2019

LS3 springs. We nabbed a set of used

takeoffs for $30. When combined

with the $70 used LS9 cam (the LS

cam offers identical performance

when run with the LM7 1.7 rockers),

our total expenditure for the cam

swap was a cool $100!

Now that we have covered the rea-

son for our purchase and the associ-

ated costs, let’s take a look at the

results. Fresh from the junkyard, our

5.3L LM7 test motor was covered

with over 200K miles worth of grease

and grime. It is amazing how well

these things run with so many miles,

especially after we saw the condition

of a couple of the cam lobes. No lon-

ger smooth and shiny, the lobes were

nonetheless intact and, thanks to

working roller lifters, offered not only

a smooth idle but plenty of