406ci Engine Rebuild - Top It Off!

We bring new life to a once-tired 406ci

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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.

1207chp 01 O  406ci Engine Rebuild Dyno 2/19

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.

1207chp 02 O  406ci Engine Rebuild Rollers 3/19

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.

1207chp 03 O  406ci Engine Rebuild Valve Covers 4/19

By the Numbers

Baseline
RPM HP
4,200 325
RPM LB-FT
3,300 439
TFS top end
RPM HP
5,600 410
RPM LB-FT
3,700 471

Short-block

Displacement 406ci
Bore x stroke 4.155 x 3.75
Rods 5.56 inches
Crank factory cast 400
Pistons forged, -20cc dish
Balanced assembly
Ignition GM HEI

Parts Swapped

Baseline
Heads cast-iron
Intake aluminum dual plane
Carb owner-modified Q-jet
Camshaft hydraulic flat-tappet
Rockers stamped steel, roller tip, 1.5:1

Cam Specs

Type hydraulic flat tappet
Duration 228/234 at 0.050
Lift 0.480/0.494 at 0.050
LSA 110

Dyno Info

Baseline TFS Top End Swap
40 degrees total timing 36 degrees total timing
91 octane 91 octane

Parts List

Description PN

Trick Flow

Top end kit TFS-K314-420-395
Camshaft TFS-31401001
Trick Flow Super 23 195 62cc chamber TFS-30400002
Aluminum, full roller, 1.5 ratio rockers TFS-31400510
Hydraulic flat tappet lifters TFS-21400001
Gasket set TFS-31400915
5/16-inch chromoly pushrods TFS-21407850
True, double roller timing chain, billet steel sprockets TFS-31478500
Cylinder head bolts TFS-92000
Valve covers TFS-44000

Quick Fuel Technology

750 cfm SS-750

Weiand

Speed Warrior intake manifold 8150

Sources

Trick Flow Specialties
Tallmadge, OH 44278
330-630-1555
www.trickflow.com
Quick Fuel Technology
Bowling Green, KY 42101
270-793-0900
QuickFuelTechnology.com
Summit Racing
Akron, OH
800-230-3030
SummitRacing.com
The Carb Shop
Ontario, CA
909-947-3575
CustomCarbs.com
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