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.
Quick Notes What we did...
What we did
Tore apart a tired small-block 350, performed an autopsy, and revived it to better-than-factory status
Build a fresh mill and learn a thing or three along the way.
Using our trusty MSA-1 decoding...
Using our trusty MSA-1 decoding booklet, we identified the block casting number 3970014 as a 350 cast between 1968 and 1979. Going further, the stamped suffix code on the VIN pad read "CKD," so we knew it was originally installed in a '72-74 Camaro, Chevelle, Nova, or Impala. The heads' casting number was 462624, as found on basic 350 iron heads made from 1976 to 1999.
Knowing that even wear throughout...
Knowing that even wear throughout an engine is normal but isolated wear is always cause for concern, we put on our detective hats and paid special attention to the No. 8 cylinder and related components during teardown. The process is called root-cause analysis. Here we see the thick crust of burned oil coating the piston crown, spark plug, and valve faces. All other pistons, plugs, and valves were clean.