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CRG Research Report - © 2013-2021, Camaro Research Group
Building the Small-Block V8 at Flint Engine
Author - John Hinckley|
Reviewed by the CRG Last Edit: 11-Jun-2019 Previous Edits: Original Release: 11-Jun-2019 & 2013 (as a pdf) |
Since 2014 is the 60th anniversary of the Chevrolet small-block V-8 engine, with over 100 MILLION of them produced since 1955 in various configurations, all based on the original block with 4.4" bore spacing, I thought it might be interesting to describe how they were manufactured. Thousands of books and articles have been written about how to rebuild or modify them, but almost nothing has ever been written about how they were originally manufactured. Even the plant that built all the standard and high-performance iron small-blocks is gone, closed in 1999 and bulldozed, and now there's just a big open space on Van Slyke Road in Flint where the Chevrolet - Flint V-8 Engine Plant stood for 44 years.
Let's go back in time to the 60's and see how this brilliant design was brought to life every day by the 4,000 folks at Flint V-8 who produced them.
Flint V-8 built 5,000 engines in up to a hundred unique configurations every day on two shifts, on two lines; line #1 ran at 170 engines per hour (one every 21 seconds), and line #2 ran at 110 per hour (one every 32 seconds). The combined output (one engine every 13 seconds) from both lines was routed to the paint booth, then to the final hot-test stands, then to shipping where they were placed in steel shipping racks and shipped out either by rail or truck to twenty different car and truck assembly plants in the U.S. and Canada. Flint V-8 was also the exclusive supplier of small-block Corvette engines. Flint V-8 was also the sole supplier of SHP ("Special High Performance") and solid-lifter small-block engines with 2.02" valves (like the 302 Z/28 Camaro). Tonawanda only built flat-top piston hydraulic-lifter small-blocks with 1.94" and smaller valves.
Aside from a difference in the casting date format between a Flint and Tonawanda small-block, the easiest way to tell a "Flint block" is to look for the square-head 1/8" NPT plug at 11 o'clock just above the timing cover. Tonawanda blocks do not have the hole or the plug. This was a result of different machining processes for drilling the oil galleries between the two plants.
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The block line consumed the most space, with the huge deck broaches the size of locomotives feeding long high-speed transfer lines that did the drilling and tapping of bolt holes, the boring and honing of cam, crank, cylinder and lifter bores, and gun-drilling of all the oil galleries. The block was clamped and precisely registered to its machining pallet by pins into two master locating holes in the pan rail surface adjacent to the fuel pump and starter pads on the right side of the block.
Machining operations were followed by high-pressure/temperature washers; from here, the fully-machined blocks entered a buffer system ahead of the engine assembly line. The other machined parts followed the same pattern - machining, washing, and buffer storage (and assembly for cylinder heads, oil and water pumps). Piston machining was physically located adjacent to the engine assembly area, for reasons we will see shortly.
There was little storage space at Flint Engine for incoming raw castings, which arrived from the Saginaw Foundry 24 hours a day via a huge dedicated over-the-road truck fleet; most castings were machined within a day or two of their arrival, some literally within hours. What little "buffer" stock of castings existed was at the Saginaw Foundry, 40 miles north of Flint.
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Freeze plugs (which have nothing to do with "freezing" - those holes are there to provide an exit path for the sand cores in the foundry "shake-out" line) and oil gallery plugs went in next, followed by the cam bearings, camshaft, then the main bearings and the crankshaft, followed by the rear main seal, main caps, timing chain and sprockets.
Each of the eight nests on each sequence-numbered tray had a ringed piston machined to the correct graded size for that bore, assembled to a rod which already had the bearings assembled and the rod torqued to "crush" the bearing shells, then disassembled, with each rod's cap and nuts in a little compartment next to the end of the rod. That tray was hung on an overhead conveyor, which took the trays, in engine sequence, directly over to the "piston-stuffing" operations on the main assembly line, within easy reach of the four operators in that station (two on each side of the line).
As the prior engine was leaving the station, each operator reached up and grabbed the piston/rod assembly he needed for his assigned cylinder on the next engine. The operator put protectors on the rod bolts, applied a ring compressor, and "stuffed" the assembly into the bore of the upside-down block; then he grabbed the rod cap and installed it (after removing the bolt protectors) with the nuts finger-started.
The crew in the second station did the same thing for their four cylinders, and the empty piston/rod tray was conveyed back to the piston/rod subassembly area to be reloaded again. The rod cap nuts were torqued with twin-spindle air nutrunners in the next station. Piston-stuffing was an incredible thing to watch at 170 engines per hour; 42 seconds total in two work stations to install eight rods and pistons is quite a contrast to the way we carefully assemble our restoration engines today. In present-day engine plants, this operation is fully automated, done by machines, with no one in sight, and modern precision machining methods and process controls result in only one bore and piston size; select-fitting pistons to bores is no longer required.
Think about how many finished pistons there were, with five nominal bore diameters (for 262's through 400's), five different piston compression heights due to five crankshaft strokes and two rod lengths, six different piston crown configurations, and up to eight different tolerance-graded piston diameters for each nominal bore diameter and crown type. Managing this level of complexity at 300 engines per hour was an industrial miracle.
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Next, the engine was turned upright to car position, and the lifters and heads were installed; the heads arrived from their machining and assembly department on a conveyor with the pressed rocker studs, valves, springs, retainers and locks already installed. The same cylinder head casting was frequently used for "small" (1.94" and 1.5") and "large" (2.02" and 1.6") intake and exhaust valves; in those cases, machining differences included a large cut on the intake side of the combustion chamber to un-shroud the flow around the 2.02" intake valve.
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The crankcase oil/vapor separator canister, intake manifold, pushrods, rocker arms, balls and nuts went on next, followed by valve adjustment and the valve covers. The engine build date and suffix code was gang-stamped on the block pad, based on the suffix code previously scrawled on the side of the block. One gang-stamp was set up each morning for each engine suffix type to be built that day; if there were 46 different types of engines scheduled to be built that day, there would be 46 gang-stamps set up and placed in a rack adjacent to the stamping operation for the stamping operator to select from. The operator selected the correct stamp holder, positioned it on the pad, and smacked it with a small sledgehammer.
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Prior to 1965, the exhaust manifolds were installed on the main engine assembly line and they were in place when the engine was painted.
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The operators then fired the engine, checked for oil pressure and oil or water leaks, set the timing, tightened the distributor hold-down clamp and chisel-staked the reference mark on the distributor base and intake, and listened for any unusual noises. Oil and water were drained, all test adapters were disconnected, and the engine was hoisted out of the test stand and placed on another conveyor that took it to the shipping area. Engines needing further attention due to test discrepancies were set aside for repairs; when repairs were completed, those engines were re-tested and sent on their way.
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When those engines left Flint, they were essentially "bare-naked"; all other final dress components on the engine were installed at the car and truck assembly plants, as indicated by the part number callouts in the applicable Assembly Instruction Manual. Fuel-injection Corvette engines departed from the carbureted-engine format somewhat, as their complete injection units and plumbing were installed at Flint Engine, leaving only a vacuum line, electrical connection, and throttle linkage to be assembled at St. Louis.
The Flint V-8 engine manufacturing sequence remained pretty much the same through the 50's, 60's and 70's, with only minor variations in conveyors, exhaust manifold installation, and painting, and progressive improvement in machining processes that improved quality and reliability.
Tonawanda Engine (New York) and McKinnon Industries (Canada - now St. Catherine's, where the current LS engines are built) also built small-block engines, but only the standard flat-top piston variety with hydraulic lifters and small valves. Tonawanda was the sole source for big-blocks, and supplied them to all assembly plants. The engine assembly process at these other engine plants was similiar to Flint. Two notable differences involve the big-block engine. Big-block engines were stamped with the ID code before the heads were installed (due to head interference) and the big-block exhaust manifolds were installed before engine paint.
Now that we have the engine built, tested, painted, and shipped, we'll follow it down the Engine Dress Line in another article - Engine Dress Line.
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