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Category: Categories > Engines > Engine Building > Tech Tip
|BUDGET BIG BLOCK CHEVY
Posted: Thu Mar 06, 11:48 PM EST
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|Author's Username: KAM||Ask the Author a Question or View Answers|
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This will hopefully be a series of articles that will chronicle a budget buildup of a 454 Chevy I am currently working on. This is a VERY cost concious job and I think it will be an interesting project. Parts will be sourced from a variety of places including ebay. My goal is to put an effective combo together that will make tons of torque and pull very hard to 6000rpm. Some things that I do to this engine will not be for everyone. There will be more expensive and fancier ways than what I detail, but that is not the point of this build-up. Typically I would just do all the machine work in my shop, but the idea here is a rebuild that the reader can do themselves. Comments are welcome of course!
A little about me
I made my living working on diesel engines and power systems. I would estimate that I have overhauled, rebuilt or done major repair to at least 1000 engines in the last 25 years. I own a business know as MAX EFFORT ENGINES. www.maxeffortengines.com This a modest engine building and machine shop. I am a certified Superflow chassis dyno tech and have training in applied failure analysis and other areas. I hope that my exprience with engines may be helpfull to someone else.
This is my first try at an article like this, please bear with me!
This current project is for a friend who wanted a street/strip type BBC.
The first step was to obtain a rebuildable core. A month of scouring the want-ad and asking around turned up a 1973 454 for $500. The engine was supposed to be in running condition when it was pulled from the camper special pick up truck it was in.
Once we had it home we pressure washed the exterior and then tore it down. All parts were kept in order. The rod and main caps were already stamped. Make sure you do this when tear an engine down. The block and heads were visually checked for cracks and the crank and the block were measured up.
Some good news and some bad. The engine had some decent parts. The block, a two bolt main, was in pretty good shape, only .002-003. taper in the cylinders. The mainline was checked with the strait edge and the lifter bores were fine. The cam gear thrust surface was also in good shape. The crankshaft was the #7416 forging. The rods were the heavier 3/8s variety, all but one rod was ok. The 049 oval port heads were in good shape, the valve guides showing little wear.
The BAD news was that the number eight rod bearing was spun and the crank was worn .023, most of the wear on one side of the journal. The number eight cylinder showed plenty of scratches from the metal being thrown into the cylinder.
The next step was to prep the block and make a decision on the crankshaft. A scat9000 cast crank was considered, but we decided to see if the forged crank could be reground without welding. The local crank grinder was able to help out. He reground the crank with a slight offset to the stroke and this gave him a little more material to work with. He also reconned a rod for us. Total cost for the grind and the rod was $120.
I cleaned up all the casting flash on the block with a die grinder and carbide burr. The oil return areas were smoothed and all the excess removed in the lifter valley. The deck surfaces were carefully cleaned by hand and checked for straightness. All bolt holes were tapped out and the freeze plug holes cleaned of scale.
We made the decision to keep the bore standard. This saved the price of the bore job. We hard honed all eight cylinders for forged piston clearance. When done we had under .001 taper and out of round avg. This was done with a heavy duty hard hone, these are made by Sunnen or Lisle Co. The trick is to use the old style Chevy/Trw pistons that require a fair amount of clearance. Some shopping on ebay turned up a set of slightly used trw domed pistons that would give about 10.2:1 compression with our heads. Buying used pistons is always a gamble, but $125 was a bargain when a new set of forged pistons are $400 and up these days. After honing the bores were cleaned with hot soapy water and a bore brush. Then the block was thoroughly pressure washed and the oil passages brushed and jetted clean. The bores were then oiled and the blocked sprayed with wd40 to prevent rust.
Thats enough for tonight. In my next segment I will go over the short block assembly, cam selection and other parts purchased.