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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)



  1. Overview
  2. Engine Assembly
  3. Final Assembly
  4. Painting
  5. Shipping

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.


The Flint V-8 Engine Plant built the engines from scratch; raw castings for the block, heads, water pump, intake manifold, exhaust manifolds, oil pump, flywheel and camshaft were supplied from the Saginaw Foundry, and raw crankshaft and connecting rod forgings were produced at Chevrolet-Detroit Forge. Unfinished cast pistons, rings, main and rod bearings, valves, springs and retainers, harmonic dampers, clutches, and timing chains were purchased from outside suppliers, with distributors supplied by Delco-Remy.

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.

The bare block looked like this when it came off the machining line and emerged from the high-pressure washer, ready for assembly.
Flint Bare Block
Here is the square-head 1/8" NPT oil galley plug just above the timing cover that identifies a Flint block. Tonawanda engines do not have the hole or the plug.
Flint Block Plug
This hole below the fuel pump boss was one of two master gage holes used to register the bare block to its machining pallet; the other one is just inboard of the starter.
Front Gage Hole
As an aside, the venerable L-6 engines were also built in Flint, but in a completely different facility - the old Chevrolet Manufacturing complex at what was called the Flint Motor Plant - in the "downtown" area by the Flint River. It closed in the 1970s.

Machining Department

60,000 iron castings, 40,000 aluminum castings, and 45,000 steel forgings were processed every day into finished parts through the Machining Department (blocks, heads, intakes, water pumps, oil pumps, flywheels, exhaust manifolds, camshafts, pistons, cranks and rods). Machining ran on three shifts, and occupied approximately two-thirds of the plant's floorspace.

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.

Engine Assembly

The block started down the assembly line upside-down, beginning with the bore air-gaging station, cam and main bearings and core plugs, heading for cam and crankshaft installation.
Bare V8 Block Inverted
The first operation on the assembly line (with the block upside-down) was to assign a sequence number and engine configuration code (the same as the suffix letters that would be stamped on the pad later on) to each block; the letter code and sequence number were marked on the sides of the block with a grease pencil. The next operation was to air-gage the finished cylinder bores for piston size, and to stamp a corresponding letter code on the pan rail adjacent to each cylinder; in those days there were up to eight different graded-tolerance sizes for each nominal bore diameter. That information was then "broadcast" electronically to the piston and rod subassembly area with the engine sequence number for later use.

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.

Piston Stuffing

At this point it got really interesting - time for piston/rod "stuffing". The piston type and gaged bore size codes had earlier been "broadcast" to the piston and rod subassembly area along with the engine sequence number. The piston department had many huge precision piston-finishing machines that cam-ground the pistons to the correct clearance for the eight graded bore sizes and finished the wrist pin bores. That area prepared a tray for each engine with eight numbered nests in it, corresponding to that engine's cylinder numbers - 1,3,5,7 on one side, 2,4,6,8 on the other side.

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.

Piston-stuffing four cylinders in the first of two stations. Note the lever-type hand tool to push the piston/rod assembly into place, and the rod journal protector tools used by the operator on the other side.
Piston Stuffing
After the piston stuffing, the bottom end looked like this. Both master gage holes for machining are visible in this photo.
Flint V8 Bottom End

Final Assembly

The timing cover and harmonic balancer went on next; the balancer was pressed on using an overhead hydraulic tool that engaged both the balancer hub and the rear end of the crankshaft, to avoid damage to the crankshaft thrust bearing. The oil pump and shaft went on next, followed by the windage tray if required, oil pan, then either the flexplate or flywheel and clutch assembly, bellhousing, clutch fork, and clutch inspection cover (on manuals).

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.

The timing cover, harmonic damper, oil and oil pump were added just prior to oil pan installation.
V8 Bottom End 2
On some later engines, the same head casting was used for more than one valve size. This 461 head for the large 2.02" intake and 1.60" exhaust valves shows the extra machining cut in the side of the chamber to unshroud the intake valve.
461 Cylinder Head Chamber

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.

From my rare photo file, here is a typical engine plant date/suffix gang stamper. One stamp was setup each day for each suffix and used all day long.
Tonawanda Engine Stamp
A typical 1969 Camaro stamp pad. The characters on the right were stamped by the engine plant, indentifying the date and engine suffix. The one on the left is the VIN derivative, stamped at the car assembly plant.
Original 1969 Engine Pad Stamp
Later engines had a sticker applied to the back of the passenger side valve cover, identifying the engine suffix code.
HE Engine code sticker
Assembly of the water pump came next, followed by the coolant bypass fitting and hose on certain engines. Installation of the distributor and spark plugs was next, followed by the temperature sender, thermostat and housing. Then the engine was ready for painting and hot-test. It was hoisted off the end of the build line and hung on a delivery conveyor to the Paint Booth.  


As engines entered the paint booth (one every 13 seconds), plastic or cardboard masks were applied to the carburetor and fuel pump mounting pads, water pump hub, spark plugs, and temperature sender. A can was placed over the distributor, and a piece of masking tape was applied to the stamp pad. Engines with aluminum intake manifolds and valve covers (or chrome valve covers) had those parts covered with vacuum-formed plastic masks. The engine was sprayed with the cheapest orange enamel available in bulk that month, with two spray operators on each side of the booth. Then the masks were removed as the engine exited the booth, and the paint air-dried as the engine moved on to have the exhaust manifolds installed. After that the engine was conveyed to the hot-test area.

Prior to 1965, the exhaust manifolds were installed on the main engine assembly line and they were in place when the engine was painted.

Distributors were identified in the engine plant by a paint stripe which had been applied by Delco Remy.
Distributor paint stripe
67 and later engines had a Flint Engine "Number One Team" sticker applied to the front of the passenger side valve cover.
Flint Sticker
Add the water pump, distributor, spark plugs and exhaust manifolds, and this is what a complete engine looked like when it left the paint booth on the way to the hot-test area.
V8 Engine Assembled

Hot Test

The engine was clamped in place and four quarts of oil were pumped into the fill tube opening, which was then plugged. Adapters connected the thermostat housing and water pump to a circulating water supply, a shunt adapter was screwed into the oil filter cavity, an oil pressure line was connected, a slave spark plug wire harness with its own coil and timing light connection was attached to the distributor and the spark plugs while a natural gas adapter elbow was attached to the carburetor pad and an air-powered starter was clamped to the harmonic damper, along with clamping exhaust manifold outlet adapters to the flex pipes that extracted the hot exhaust fumes.

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.


When the engine arrived in the shipping area, it was routed based on its suffix code to a specific dock location, where it was plucked off the delivery conveyor with an air hoist and placed in a steel shipping rack with three other identically-coded engines. Full racks were then taken by a fork truck and loaded into a waiting railroad car (with 240 to 300 engines in a railroad car), or into a truck if it was a rare "expedited" shipment. With up to 100 different engine configurations, and 5,000 engines per day shipping to 20 different assembly plants all over the country, and providing engine assemblies for service, Flint Engine was, for its day, an industrial miracle in terms of production control.
An actual photo of the 1955 V8 hoisted from the delivery conveyor for placement in its shipping rack. The generator brace shown was frequently damaged in shipping, and was later reallocated for installation at the car assembly plant. Note the "log" exhaust manifolds, no oil filter pad, and no side motor mount bosses.
1955 V8 Shipping

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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