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Old 23rd March 2007, 20:50   #1
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Default history of the chevy blocks

Chevy Production Small Blocks
1953, Chevrolet introduces the Corvette with the 235 cid "Stovebolt 6" cylinder reworked to turn out 150 HP up from 115 HP. The renamed "Blue Flame Six" does not overly impress performance enthusiasts. Rumor is that Ford will introduce an overhead valve V8 in 1954 and a two seater in 1955 to compete with the Corvette. 1954, Ford introduces their overhead valve V8. Sales of the Corvette are languishing and market share is being lost to Ford. To keep up with Ford and try to save the Corvette from extinction Chevy rushes a V8 into development. Oldsmobile and Cadillac had introduced modern V8ís in 1949 and Buick followed in 1953. Only Chevrolet and Pontiac were holding back and Pontiac had been working on a V8 since the end of the war.

Under the direction of Ed Cole, the Chevy 265 cid V8 was rushed into production and was introduced in 1955 along with Pontiacís 287 cid entry into the market. The new engine had some initial teething problems but these were quickly resolved and the Chevy small block evolved into the most successful V8 engine of all time with over 16.5 million being produced in ten different displacements over the next forty years. It is still with us today as the 5.7 liter (350 cid) V8. It saved the Corvette from extinction and restored Chevy to its former dominance over Ford. Despite numerous design improvements over the years the engineís basic geometry and key dimensions have been maintained unchanged. This continuity has contributed to the interchangeability of parts and tremendous popularity of the small block amongst performance and other enthusiasts. The availability of original and aftermarket parts for the small block Chevy V8 is not equaled by any other engine.

The 265 in the 1955 Corvette was rated at 195 HP, a substantial improvement over the six cylinder. For 1956 maximum HP for the 265 was raised to 225 HP. In 1957 the 265 was bored out to 3.875" resulting in the venerable 283 cid engine. Horsepower available for the Corvette was raised to 283 HP with fuel injection. In 1962 the 283 was bored and stroked to produce the famous 327 cid engine. The 327 was available in the "fuely" Corvette with up to 360 HP. A stroked version of the 327 was introduced in 1967 giving 350 cid.

In 1967 the 302 cid V-8, made by installing a 283 crank in a 327 block (4.00 x 3.00 inch bore and stroke), was introduced for SCCA Trans Am competition. The 1967, 302, Z-28 had 2 bolt mains; later 302ís had 4 bolt mains. The crank was forged steel. The Z-28, 302 cid engine used Corvette L-79 big port heads, with 11:1 compression ratio, 2.0 inch intake valves and 1.6 inch exhaust valves. Solid lifters and 1.50:1 rockers provided 0.485 inch valve lift. Optional cams could be fitted. Standard intake was an aluminum tuned-runner manifold with 4 barrel, 780-800 cfm Holley. The engine was officially rated at 290 HP but produced closer to 360 HP. In 1968 the 327 was given a beefed up crankshaft with 2.45" mains and 2.10" crank journals. The same year the 307 was introduced which basically was a 283 block with a small main bearing 327 crankshaft 3.875" bore x 3.25" stroke. For 1970 the largest displacement small block of 400 cid was introduced with 4 bolt mains; in 1973 the 400 was reduced to 2 bolt mains. Because of the 400ís large bore of 4.125" and cylinder spacing of only 4.40" there is no water jacket between the cylinders at the center and the cylinders are referred to as "siamesed". Although production of the 400 was stopped in 1980 there is still great interest in the engine today due to its high displacement and low cost.

The small block V8 has a deck height (centerline of crankshaft to cylinder deck measured along the centerline of the bore) of 9.025" and a height (centerline of crankshaft to top of engine along the center of the V) of 9.805". Cylinders are spaced on 4.40" centers on each bank and the centers of cylinders on the two banks are offset to accommodate the two connecting rods on each crank journal. The small blocks have been produced in 3.671", 3.736", 3.750", 3.875", 4.000" and 4.125" bores and strokes of 3.00", 3.10", 3.25", 3.48", and 3.75". Crankshaft bearings have been produced in small 2.30", medium 2.45", and large 2.65" diameters with rod journals of 2.00" and 2.10".

The Gen.I and II smallblocks as we know them will be phased out over the next few years and replaced with the Gen.III motor. The Ď98 "LS1" motor found in Corvettes, Camaros and Pontiac Firebirds are the first of the new style smallblocks. The Gen.III will soon be found in trucks applications using a cast iron Gen.III block instead of the aluminum block found in the LS1ís.

265 55-56
283 57-67
327 62-67
302 67
350 67-94
302 68-69
327 68-69
307 68-73
400 70-72
400 73-80
262 75-76
305 76-94
267 79-81
All 1st generation small blocks used a 5.7Ē rod length except for the
400 cid engine which used a 5.565" rod length.
Firing order 1-8-4-3-6-5-7-2


Generation II and later
350 LT5-89
350 LT1-92
265 L99-94
350 LS1-97
293 LR4-99
364 LQ4-99
325 LM7-99


L99 is Gen. II 94 and later 4.3 liter
LT5 used from 89-95 in ZR1 Corvette
LT1 is Gen. II engine
LS1 is Gen. III engine 97 and later
LR4 99 and later 4.8 liter Vortec
LQ4 99 and later 6.0 liter Vortec
LM7 99 and later 5.3 liter Vortec

Chevy Production Big Blocks

The Chevy big block was introduced in 1965 with a 396 cid Mark IV engine developed from the 1963 Datona mystery engine. The engine was basically developed as an answer to the highly successful GTO with its 389 cid engine introduced in 1964. The 396 was first offered in the Chevelle at 375 HP, in the full size Chevy as 325 and 425 HP versions and in the Corvette with up to 425 HP. In 1966 the 396 was bored out to 4.250" producing a 427 cid engine. The 427 was offered in the 1967 Impala SS rated at 385 HP and in the Corvette it was first offered in 1966 and was uprated with 3-2 bbl carburetors to 435 HP for 1967.

In 1967 the L88 427 was also provided in approximately 20 Corvettes with an advertised HP of 430 but actually producing in excess of 550 HP. The L88 required minimum 95 octane gas to avoid possible damage to the engine and was meant to be strictly for racing. 1970 saw introduction of a stroked 427 resulting in a 454 cid engine. The 454 was offered in the 1970 Impala, Chevelle SS, El Camino SS and Monte Carlo SS in a 360 HP version and in the Chevelle and El Camino SS in a 450 HP version. The 1970 Corvette LS-6 was offered with the 390 HP 454 cid engine. 1970 also ushered in the 402 cid engine which was also known as the 396 in some Chevys and the big block 400 in others. In the 1970 Camaro SS, Chevelle SS and Nova SS the 402 cid engine with 375 HP was known as the 396 and the cars carried the 396 badge. From 1970 to 1972 the 402, 454, 465 and 495 cid engines were introduced.

The short big block V8 has a deck height (centerline of crankshaft to cylinder deck measured along the centerline of the bore) of 9.80" and a height (centerline of crankshaft to top of engine along the center of the V) of 10.75". Cylinders are spaced on 4.84" centers on each bank and the centers of cylinders on the two banks are offset to accommodate the two connecting rods on each crank journal. The big blocks have been produced in 3.935", 4.096", 4.125", 4.250", and 4.440" bores and strokes of 3.47", 3.76", and 4.00". Over the years from 1965 to 1995 the big blocks were offered in nine different displacements from 366 cid to 502 cid.

Below is a table of the main dimensions for all production big block Chev engines from 1965 to 1995.


Production Big Block V8ís

CID Years Bore Stroke Block Material Actual Liters Main
CID Bearing
396 65-69
366T 66-95
427 66-69
427T 69-95
427 69
430 69
454 70-91
402 70-72
465 70-71
495 70-71
495 72
502 92-94

All big blocks have 2.75" main bearings and 2.20" rod bearings and all production big blocks used a 6.135" rod length. T is Tall (or long) block with a deck height of 10.20" and vertical height of 10.75".
Firing order 1-8-4-3-6-5-7-2

this info was taken from many sites.
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Old 23rd March 2007, 21:47   #2
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Dude,give the links of all the sites from where u compiled the info.
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Old 23rd March 2007, 22:17   #3
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hotrodders.com
sportscarforums.com
wikipedia.com
and some more.

thought of putting up also about the ford blocks.
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Old 23rd March 2007, 22:20   #4
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Pawan - nice compilation.
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Old 24th March 2007, 00:03   #5
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hey nice i am in love with chevy big blocks the sound they produce and amount of power they have
My personal fav. is the chevy 454 the ones found under the hood of the chevelles
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Old 24th March 2007, 09:23   #6
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why didnt you include the DOHC 32-valve V8 from the corvette ZR-1? This engine is the most exotic V8 ever made by an American manufacturer. 5.7 liters, designed by Lotus and built by Mercury marine, NOT pushrod, and revved to 7200 RPM too.
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Old 24th March 2007, 13:42   #7
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Quote:
Originally Posted by ananthkamath View Post
why didnt you include the DOHC 32-valve V8 from the corvette ZR-1? This engine is the most exotic V8 ever made by an American manufacturer. 5.7 liters, designed by Lotus and built by Mercury marine, NOT pushrod, and revved to 7200 RPM too.
thanks man forgot about that here is some info i have about the zr1:

That Corvette was the 1990-95 ZR-1, and it's the most exotic production 'Vette ever built.

Quote:
The standard Corvette was plenty fast with its conventional 245-horsepower V-8. But the ZR-1 had a custom 375-380 horsepower V-8 from Lotus -- the British sports car and world championship Grand Prix race car builder, which does work for major automakers. Both engines had a 5.7-liter displacement, but that's about all they had in common.



Why Lotus? Because Chevy had considered a turbocharged V-6, twin-turbocharged V-8 and even a non-turbocharged 600-horsepower V-8, but found them too noisy or inefficient. It needed a quiet, docile, smooth, economical engine at home in heavy traffic and on race tracks. Morever, GM bought Lotus about the time Chevy and Lotus representatives met in 1985 to initially discuss the ZR-1 engine, which took about two years to develop.

Such an engine never came cheap, so the Corvette ZR-1 was General Motors' most expensive 1990 car and its new flagship model. The ZR-1 announcement price was $58,995, but soon jumped to $64,138.

The ZR-1 got its model designation from the "ZR-1'' option package, which added $27,016-$31,683 to the standard Corvette hardtop's list price -- making it the most expensive auto option in Chevy history.

The Corvette ZR-1's hand-assembled 32-valve, dual-overhead-camshaft V-8 had a key-operated "valet switch.'' It limited horsepower to 150-200 when a ZR-1 owner handed the keys of the car to parking lot attendants or teen-age family members.
ps: any one have some good info on the ford blocks i don't have any thing good.

Last edited by pawan : 24th March 2007 at 13:53.
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