1969 Chevy Camaro Small Block Engine Buildup - Thrasher Camaro Part II

Building a Street-Tough 460hp Small-Block

Mark Stielow Feb 1, 1999 0 Comment(s)

Step By Step

The Thrasher is intended to perform as well as a modern musclecar through the use of simple modifications and aftermarket bolt-ons. It is being built to drive on the street, compete in the One Lap of America, drive on the Hot Rod Power Tour, and more.

Ray Banyas, from Victory Engines in Cleveland, Ohio, performed the machine work and assembly. Here, he marks the area on the oil pan rail that will be drilled for the oil dipstick tube. The Bow Tie block is Chevy's aftermarket cylinder block that offers thicker cylinder walls and stronger construction, but some machine work is necessary for street use. The block also requires the use of a two-piece rear main seal adapter since these blocks are machined for late-model one-piece rear main seal-style crankshafts.

The Thrasher 406 uses a Crane roller camshaft with horizontal tie bar lifters. When using a Bow Tie block, this requires the tops of the lifter bores to be machined down to clear the tie bars. This process, along with the installation of four-bolt main caps, the cylinder boring and honing, stroker crank clearancing, and machining the deck, were done by Summit Racing Equipment, in Akron, Ohio. Victory Engines polished the lifter valley to promote oil flow.

The rotating/reciprocating assembly is built to withstand the rigors of repeated, hard street use, which for me borders on endurance racing. The forged Cola 3.750-inch stroke crank (with 350 style 2.100-inch mains) swings 6.000- inch Trick Flow mid-weight rods holding Wiseco pistons.

A good tip is to check the straightness of the crankshaft by placing it in the main saddles, putting a dial indicator on the center main journal, and slowly turning the crank. The runout should be less than 0.0005-inch.

Once the rod and main bearing clearances are set at 0.002-inch and the crankshaft endplay set at 0.015-inch, the mains were torqued down to 75 lb-ft on the ARP studs.

The piston/rod combination consists of a 4.155-inch diameter Wiseco forged aluminum piston and a 630 gram mid-weight Trick Flow 6.000- inch rod with floating pins. A Federal Mogul moly-faced 1/16-inch ring package seal the combustion pressure.

Using a tapered ring compressor, the lubricated piston/rod assemblies are installed in the bore. Be sure to orient the ring end gaps in the proper location on the piston. It's also a good idea to place plastic covers over the rod bolts to prevent nicking a rod journal.

Once each piston and rod assembly is in place, the ARP fasteners are lubed and rod bolts are torqued. It's an excellent idea to use a rod bolt stretch gauge when torquing the rod bolts since this establishes the proper bolt tension.

The Crane Street Roller cam offers outstanding lift with the shortest duration to better handle street driving. The Street Roller also offers a cast-iron distributor gear--a better choice than the bronze distributor drive gear. The timing chain is a Crane billet gear unit.

The timing cover is a Summit cast aluminum piece that needed about 0.035 inch machined off its inside face to arrive at the proper end cam play (0.015-inch). A thrust button from Summit was used on the cam. Stielow used ARP bolts to keep it all connected.

The Hamburger's oil pan was modified slightly to fit in the car. The number to remember is 91/4 inches--that is the maximum length the sump can extend from the rear of the pan, or the Camaro drag link will hit it. Headers may also cause a problem if they tuck in too closely, since they may hit the kick-out portion of the pan. We used a set of 17/8 Hedman race headers that cleared the pan no problem. I modified the collectors to use a regular three-bolt flange and added an 02 sensor. If you are going to use this pan, get the pump, pickup, starter, and other pieces that go with it, as everything is designed to work together.

We flow tested the Edelbrock heads and found good flow throughout the entire lift range. This will contribute to excellent torque and respectable horsepower.

The cylinder heads rest on a 0.041-inch-thick PN 1034 Fel-Pro head gasket along with Fel-Pro's PN 1206 intake gaskets. The GM Performance Parts valvecovers rest on Fel-Pro's new reusable silicone gasket which really helps clean up those pesky oil leaks.

I like broad powerbands because there is nothing better for street driving or endurance racing, which is what I like to do. For killer performance, you need a thumper engine. While work on the Thrasher continues, we assembled a 406ci small-block that was tasked to deliver both killer power and acceptable street manners.

Pro Touring is about power, but with its own definition. While horsepower is cool and will impress the locals at the burger stand, we were looking for a combination of strong torque and good horsepower. We wanted the best of both worlds. The easiest way to get there was with displacement, but a big-block puts too much weight on the nose of the car. We elected to stick with a 406ci small-block but build it the right way with quality parts.

Follow along as we assemble an engine that will impress anyone you take for a romp in your hot rod. This engine is designed to provide strong power over a wide powerband using only off-the-shelf components and run trouble-free for thousands of miles.

Power to Go
For simplicity, all the components for this 406ci were ordered through Summit Racing Equipment, in Akron, Ohio. They offer very competitive prices and usually have the product in stock, ready to ship, which makes it easy to get to work assembling the engine. All the components were ordered from Summit, but some machining was still required (like the dipstick tube hole needed to be drilled in the Bow Tie block). Victory Engines, in Cleveland, Ohio, did all the detail machining and assembly while Westech Preformance, in Mira Loma, California, performed the dyno testing and assisted with the tuning.

COMMENTS

subscribe to the magazine

get digital get print
TO TOP