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1972 350 Chevrolet Pickup Engine - Tech - Build Your First Engine

Part One The Short-Block

Steve Magnante Jul 25, 2007

Lucky you, you're about to do something that only comes around once in any hot rodder's life: building your first engine. You see, if you stay at this game long enough, you reach a point when the thrill of discovery fades a little bit. Oh, it's always a buzz when you twist the key on your latest creation, but there's nothing like that first build. So savor the moment and tag along as we rebuild this 350 small-block and show you some tricks and tips we've learned over the years.

Keep in mind, while you can do most of the disassembly and reassembly in your garage-or kitchen, if she's a particularly forgiving gal-several operations can only be performed by a competent machine shop. With help from the crew at JMS Racing Engines, we'll walk you through them so you know what your particular engine needs and you can discuss the work with your machinist.

Selecting a rebuild candidate shouldn't be too hard, thanks to the millions of small-blocks turned out in the five decades since its introduction. The best scenario is to pull an engine from a running car or truck; this way, you can listen for smooth combustion, observe the oil pressure and coolant temperature behavior, and get a solid sense that there's nothing terminal going on inside the block. Buying beached whales-you know, those engines sitting loose on the ground at the swap meet-is much riskier. Your only assurance that there are no cracks, warps, or fractured parts is the seller's word. Choose wisely and make sure the seller will refund your purchase price if terminal illness is lurking. Keep walking if it's an as-is deal.

The subject for this story is a '72 vintage two-bolt main 350 we yanked from a Chevy pickup street rod. It ran pretty well but had a nasty habit of fouling the No. 8 spark plug every few thousand miles. Aside from that mystery, it had good acceleration, the oil pressure read 25 psi at idle/60 psi cruising, the temp gauge lived at 190 degrees F, and it didn't make any sick noises. But it was tired, and that No. 8 hole wasn't going to fix itself. We could make it better, and so can you. Let's dig into the engine and rebuild the short-block. Next time, we'll revive the top end and prove our efforts with a dyno session.

Powerhouse cast-iron 3.750-stroke crankshaft, 400-style 8-inch balancer, 400-style 168-tooth flexplate, and forged 5140 steel 5.7-inch rods; King tri-metal, chamfered for radiused crank rod bearings; ARP 31/48-inch rod bolts; forged aluminum four-notch flat-top pistons; press-fit piston pins; Hastings moly- faced 2M139-030, 51/464, 51/464, 31/416-thick rings; King tri-metal, chamfered for radiused crank main bearings.

383CI Small-BlockBuild Sheet
Specifications not listed are the same as stock. Except as noted, all dimensions are in inches or fractions thereof.

Displacement 383ci
Bore x Stroke 4.030 x 3.750
Compression 10:1
Rod, center-to-center 5.700
Piston deck height 0
Rod bearing clearance 0.0026
Crank endplay 0.0060
Piston ring endgap 0.022 top;
  0.018, second
Piston to wall clearance 0.002
Main bearing cap torque 70 lb-ft*
Rod bolt torque 45 lb-ft*


JMS Racing Engines
El Monte, CA
Powerhouse Products
Memphis, TN 38118



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