Chevy inline 6 engine & performance info

Here is some History on the 6 cylinder inline Chevy straight six engines. The Chevrolet inline 6 started with the stovebolt engine & developed to the high performance 292 Chevrolet 292 L6 engine

First Generation

Type inline-6
Production 1929 - 1936
Bore 3.3125 in (84.1 mm)
Stroke 3.75 in (95.3 mm)
Displacement 194 cu in (3.2 L)
Power output 50 hp (37 kW)
The first mass-produced GM inline-6 was introduced in 1929 on Chevrolet cars and trucks, this engine replaced the inline-4. The straight six stovebolt engine was produced from 1929 to 1936.

It was 194 cubic inches (3.2 L) in size and produced 50 hp (37 kW). This engine used a forged steel crankshaft with three bearings and cast iron pistons. Bore and stroke was 3.3125 in (84.14 mm) by 3.75 in (95.25 mm). The 194 was shared with Chevrolet and GMC trucks for 1935 and 1936.
A balanced crankshaft was introduced for 1932, while a higher (5.2:1) compression ratio upped output to 60 hp (45 kW). A new cylinder head two years later pushed output to 80 hp (60 kW).

A 181-cubic-inch (3.0 L) version was used by Chevrolet and GMC trucks in 1935 and 1936.

A 207-cubic-inch (3.4 L) variant was used by Chevrolet and GMC trucks in 1934, 1935 and 1936.

The 2nd inline six produced by Chevrolet was introduced in 1937 & was made until 1963. This engine was also used in Chevrolet trucks.

The New Chevy 6 was larger again with 216-cubic-inch (3.5 L) it boasted a 3.500” (88.90mm) bore and a 3.750” (95.25 mm) stroke. A four main bearing crankshaft & a raise to 6.5:1 compression the new engine produced 85 hp (63 kW). Chevrolet developed a new cylinder head in 1941 the new cylinder head increased hp to 90 hp (67 kW) . In 1949 the compression was raised to 6.6:1 gave an extra 2hp to boost the output to 92 hp (69 kW).

The 235.5-cubic-inch version was released in 1949 it was used in large trucks. Chevrolet increased the bore (3.5625” or 90.49mm) and stroke (3.9375” or 100.01mm). The 235-cubic-inch (3.9 L) was introduced in 1950 to give a bit more power for the new 2 speed Powerglide auto transmission, In 1953 Hydraulic lifters were added & a pressurized oiling system for cars ordered with the Powerglide auto trans. The 216-cubic-inch (3.5 L) continued to be standard powerplant for cars with the 3 speed manual transmission until 1954 when the 235-cubic-inch (3.9 L) became the standard powerplant on all its cars. Two versions were used in 1954 cars - a solid-lifter version with 123 hp (92 kW) for standard transmissions and the hydraulic-lifter 136 hp (101 kW) version (The Blueflame) for Powerglide use.
From 1954 to 1963, the high-pressure 235-cubic-inch engine with mechanical valve lifters was used in trucks. From 1956-1962, all 235-cubic-inch engines used in cars had hydraulic lifters.
The 1953 Corvette engine had the high-pressure 235-cubic-inch engine equipped with mechanical lifters. A 150 hp 235 engine was used in the 1954 Corvette and into 1955. The 235 ci Corvette used the same highlift camshaft as used in the 261 truck engine and triple side draft Carter carbs & a Powerglide transmission & a dual outlet exhaust manifold. The 235 and 261 truck engines were also used by GMC for truck in Canada.

Third member of the Chevrolet inline 6 family was introduced in 1962 to 1988.The new engine was lighter and had a different bell housing bolt pattern. Both auto & manual bell housings & starter motors became interchangeable with Chevy small block and big block V8s.
Other changes on the 3rd generation engine was the crankshafts now had 7 main bearings not 4 like the earlier straight six, Chevrolet decreased the stroke from 3.9375" to 3.25 to produce a 230 ci engine. A new wedge type combustion chamber like the V8 was also used. The valve train was changed from a shaft type & an increase from 1.5 to 1 ratio was increased to 1.75 to 1 like the big block chevys used, Chevrolet passenger cars used the new style engine until 1977, In the Camaro,Chevy Nova & full size trucks it was used until 1979. These vehicals previously used the Stovebolt sixes. In the mid-1970s, the V6 engine like the Buick V6 231& later the 200 ci & in the 1980 the 229 3.8 V6 Chevy to over from the inline six in passenger car. GM continued to use the inline 6 in trucks and vans until 1988. Brazil used the straight six in the Chevrolet Opala from 1969 to 1992 . The inline Chevy six were converted for marine use by Volvo Penta & mercrusier & were also used to run power generation & used in forklifts.

In 1970 GM made the inline 6 the base engine with the Chevy II/Nova with either a 230 or 250 ci engine, Applications:
1962-1969 Chevy II
1967-1971 Postal Jeep
1968-1992 Chevrolet Opala (Brazil)

194 Chevy straight six

194 was used in both Chevrolet and GMC trucks.
1962-1967 Chevy II
1964-1967 Chevrolet Chevelle
1965-1966 Studebaker Commander, Daytona 1966 only, Cruiser and Wagonaire

230 Chevy straight 6
The 230 Replaced 235 cubic inches (3.9 L). It was also used by Chevrolet and GMC trucks, primarily the half-tons. It produced 140 hp (100 kW). The 230 had a firing order of 1-5-3-6-2-4 rotating clockwise. This engine was used on the following vehicles:
1964 Chevrolet Chevelle
1965-1968 Checker Marathon
1965 Chevrolet El Camino
1966-1970 Chevrolet Nova
1966 Studebaker Commander, Wagonaire, Daytona and Cruiser
1967 Chevrolet Chevelle
1967 Chevrolet Camaro
1968 Chevrolet Chevelle Malibu
1969 Chevrolet Camaro
1969 Chevrolet Chevelle

3.8 Pontiac L6
The Pontiac 3.8 was a special SOHC version of the standard 230-cubic-inch (3.8 L) I6. An optional W53 version on the Firebird produced 215 hp (160 kW).
This engine was used on the following vehicles:
1967 Pontiac Firebird
1967 Pontiac Tempest Sprint coupe

250 Chevy inline six
The stroked 250 version produced 155 hp (116 kW) for Chevrolet and GMC. Between 1975 - 1984, an integrated cylinder head was produced, with one-barrel intakes for passenger cars, and two-barrel intakes for trucks after 1978.
Passenger car use of the 250-cubic-inch (4.1 L) engine was discontinued after the 1979

This engine was used on the following vehicles:
1966-1984 Chevrolet (passenger cars to 1979, trucks/vans to 1984)
1968-1976 Pontiac Firebird
1968-1970 Pontiac Tempest
1968-1976 Pontiac LeMans
1968-1969 Buick Special
1968-1972 Oldsmobile F-85
1975-1976 Oldsmobile Cutlass
1971-1975 Pontiac Ventura
1968-1971 Buick Skylark
1968-1979 Chevrolet Camaro
1969-1979 Checker Marathon
1968-1992 Chevrolet Opala (Brazil)

L22 6 cylinder Chevy
The L22 was a 250-cubic-inch (4.1 L) I6 engine produced from 1967 to 1979. The '78 Camaro had 105 horsepower (78 kW) and 190 ft·lbf (260 N·m) of torque with the 250.

LD4 Chevrolet 6 cylinder
The LD4 was a 250-cubic-inch (4.1 L) I6 engine produced strictly in 1978.

LE3 6 cylinder Chevrolet
The LE3 was a 250-cubic-inch (4.1 L) I6 engine produced from 1979 to 1984.

292 C.I Chevrolet 6 cylinder
The 292 was only used in Chevrolet and GMC trucks; the block deck is taller, along with a relocated passenger-side engine mount. These were produced between 1963 to 1990; production of the engine shifted to Mexico after 1984.

L25 Chevrolet 6 cylinder
The L25 was GM's "last" pushrod straight-6 engine, produced from 1977 to 1988. It was used in Chevrolet trucks, displaced 292 cubic inches (4.8 L) and produced 115 hp (86 kW) and 215 ft·lbf (292 N·m).

The Chevrolet straight six has been used from the early days in sedans & trucks, It became popular with many hot rodders & racers. Over the years there have been many brands of headers, aluminum cylinder heads, hotter grind camshafts, 2 & 4 barrel manifolds + a huge range of multi carb intakes from speed equipment companies both large & small. Many back yard & home work shop creations have also been invented.

Pictures below show the Chevy Blue flame straight six inlet & exhaust manifold compared to the later Chevy straight six engine. Note the blueflame manifold has round exhaust ports. The later L6 has rectangular ports.

chevy inline manifold

blueflame chevy six manifold

Chevy Straight six engine specs bore and stroke sizes

194: 3.563x3.25
215: 3.750x3.25
230: 3.875x3.25
250: 3.875x3.53
292: 3.875x4.125

firing order
1-5-3-6-2-4
Chevrolet straight six engine were available in many body styles.

Chevy Nova
Chevrolet Camaro
Buick Apollo
Buick skylark
Pontiac Firebird
Tempest, LeMans
Chevelle/Malibu
Buick Special/Grand Sport
Biscayne/Bel Air/Impala/Caprice
Chevy Blazer
Chevy pickup trucks
GMC trucks

Chevy straight six crankshaft strokes.

Straight six Chevrolet crankshafts from these engines will interchange. There are 3 basic crank types.

194/230 (3.25" stroke)

250 (3.53" stroke)

292 (4.125" stroke)

The 292 cubic inch straight six engine has a different conrod journal diameter. When swapping cranks it is recommended both crank & rods be swapped as an assembly.

Some parts that will & wont interchange between Chevy engines
starter motors,

Most chevy sixes run a through bell housing starter motor

harmonic balancers,

Do not interchange with small block or v6 chevys as the pulley on the balancer is integrated with the balancer, bolt on pulleys are used to run air con,power steering & air pumps.
Push rods,

The pushrod length on the chevy six is a length of its own & will not interchange with small or big block Chevrolets
Conrods & rod bearings,

Due to rod length & big end sizes they do not interchange with v8 engines.
rocker arms & roller rockers,

Despite having a ratio very similar the rocker length is not the same
camshafts and timing gear sets,

The 292 chevy six does not interchange with the smaller cube engines.
Fuel pumps,

292 Chevrolet straight six engines had the fuel pump switched to the other side of the engine block, The lobe on the camshaft that operates the fuel pump lever is not in the same location as the smaller cubic inch engines.

Distributors

from v6 Chevrolet, small or big blocks do not swap either

Information that can also be useful.
crankshaft tunnel alignment is very important when changing rotating assemblies .

Crankshaft weights on casting # 407/407N are 10 lbs lighter than crankshaft casting # 802 the conrod,piston,flywheel & harmonic balancer weights will also need to be matched if swapping cranks.

Cylinder heads can be shaved .060 to .080 without affecting the head face.

Head bolt bosses that run through the intake ports can provide more airflow if reduced and reshaped or removed & replaced with crush tubes

It is a known problem that the blocks can get cracks from the head bolt on the front drivers side to the water pump. This can be prevented by installing head studs when rebuilding,

Any straight six Chevy engine made before 1975 was not designed to run unleaded fuel. It is advised to fit hardened valve seats & higher grade exhaust valves to over come future problems

Fiber camshaft timing gears run a lot quieter than steel or aluminum cam sprockets. The down side is they can strip at any time & is more prone in older engines. It is advised if you are changing your camshaft or hotting up your chevy inliner that both cam & crank gears be repaced as they are designed to be run as a matched set.

This mad straight blown six cylinder powered flamed altered leaving the line...in a case like this "6 in a row is the only way to go"

Cylinder head torque settings on chevy inline 6 cylinder engines should be pulled down in 3 stages.

first stage 40 foot pounds

second stage 60 foot pounds

final stage 85 foot pounds on the 2 front cylinder head bolts & 95 foot pounds on all other head bolts except the front 2.it is recommended to install the water pump before doing up the head bolts

allways start in the center & go from left to right & work out towards the ends.