This 406 normally is at home in between the fenders of a ’67 Nova. After years of feeding nitrous through it, we decided to give the engine a simple makeover by swapping out the old pieces in exchange for a complete bolt-on system from Trick Flow Specialties.
Taking a closer look at the original mill, this gem was pieced together on a tight swap meet budget and relied on a liberal shot of nitrous to catch any would-be challengers at the local grudge night sessions. It featured an old set of cast-iron heads, a Quadrajet carb, a flat tappet camshaft we borrowed, and a set of stamped-steel roller-tipped rocker arms.
For this month, we left the short-block alone with its factory 5.56-inch rods and cast 400 crankshaft. We figured it was the perfect candidate for a top end upgrade and comes complete with everything being supplied to transform our little sleeper. We should mention that Trick Flow Specialties offers each of the items used here individually, however we took the easier route and ordered the all-in-one package.
This particular kit included a pair of TFS’ Super 23 aluminum cylinder heads, and comes with the cam and lifters, all the necessary gaskets, pushrods, full roller 1.5:1 ratio rockers, and a new double-roller timing chain. To finish up the order, we also went with a Quick Fuel Technology 750-cfm carburetor and a Weiand Speed Warrior dual-plane intake manifold.
We didn’t want to turn this into an all-out track piece; on the contrary, we wanted to keep its street manners intact and decided on a mild hydraulic flat tappet camshaft, spec’d out at 228/234 degrees of duration and 0.480/0.494 lift with a 110 LSA. The Trick Flow Specialties Super 23 195 heads come standard with a 62cc chamber, which produced a pump gas–friendly 9.7:1 compression with our dish pistons.
To document our changes, we headed over to The Carb Shop in Ontario, California, where we baselined the original setup and put the new combination to the test. The baseline figures were modest at 324 hp, but did surprisingly well in the torque department with 439 lb-ft. With the first set of numbers secured, we took a couple of hours to swap over to our new combo and found a significant improvement with an increase to 409 hp and 471 lb-ft! Now for the fun part, seeing how the Nova reacts with an additional 150-shot of nitrous . . . stay tuned.
By the NumbersBaseline
|TFS top end|
|Bore x stroke||4.155 x 3.75|
|Crank||factory cast 400|
|Pistons||forged, -20cc dish|
|Intake||aluminum dual plane|
|Rockers||stamped steel, roller tip, 1.5:1|
|Type||hydraulic flat tappet|
|Duration||228/234 at 0.050|
|Lift||0.480/0.494 at 0.050|
|Baseline||TFS Top End Swap|
|40 degrees total timing||36 degrees total timing|
|91 octane||91 octane|
|Top end kit||TFS-K314-420-395|
|Trick Flow Super 23 195 62cc chamber||TFS-30400002|
|Aluminum, full roller, 1.5 ratio rockers||TFS-31400510|
|Hydraulic flat tappet lifters||TFS-21400001|
|5/16-inch chromoly pushrods||TFS-21407850|
|True, double roller timing chain, billet steel sprockets||TFS-31478500|
|Cylinder head bolts||TFS-92000|
Quick Fuel Technology
|Speed Warrior intake manifold||8150|