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.