Big Block Chevy Block Casting Numbers

1958 marked the year Chevrolet brough out the 348 C.I.D. V-8.This block was completely different from the small block Chevy,it also marked the begining of the Big Block Chevrolet Family.The casting numbers can be found on the rear drivers side flange that meets with the tranny bellhousing.Date codes can be found on either the top center of the bell housing flange or the passenger side of the block near the freeze plug locations.

The famed 409 was out in 61,and at first glance can be had to distinguise from the 348.Casting numbers and date codes are the best way to find out.1961 was also the last year on the 348 in passenger cars but,was used later in trucks and buses.

The 427 Mystery Motor showed up at the NASCAR tracks in 63.None of the caracheristics of the 348 or the 409 were present with the new big block,like the "W" shaped heads.The first of the Mark IV engines debuted as the 396 in 65.63 was the last year of the 409 in passenger cars,seeing limited service with some 65 full sized Chevys..The Mark IV can still be seen in service today.

Available in either standard or special High Performance versions.Both versions used the same casting numbers in the early years,the difference being weather or not the block was drilled and tapped for 4 bolt main bearing caps and is the only way to tell the diiference.

Appearing in 1966,to the approval of Chevy fans and the detriment of the competition was the 427.Reaching it's zenith in 69 as an exotic all aluminum block and heads high performance engine known as the ZL-1.A hand full of Corvettes and Camaros received this option and that makes then extremely difficult to find today.Most ended up as drag racing engines and so not many survived.

Mark IV engien have also been converted to truck blocks,or "tall blocks".Although essentially the same as other big block Chevys,they feature a longer crankshaft centerline to deck distance and are not normally considered desirable  for passenger cars.The only was to know is to check the cast numbers.

1969 was officially the last year of the 396 but,many cars were know as 396 SS's afterward.A slightly larger bore gave the 396 a displacment of 402 CID for the 1970 model year.Many of these vehicles were marketed with 396 SS emblems on the fenders and 402 on the sticker under the hood.To make things more interesting Chevrolet marketed some of the 402 as Big Block 400 engines,like in 71.So if you have one of these engines,it's a 402 or a slightly bored out 396,you get the point.As a result Chevrolet described the big block as a 400 4 barrel and the small block as a 400 2 barrel.

Appearing in 1970,the 454 boasted the highest advertised horsepower and torque ratings with the LS-6 @ 450 HP.There were plans for a LS-7 with 465 HP and they could be purchased over the counter,they were never reportedly installed in any applications.

The decline of the horsepower/cubic inch wars came about with insurance rates and government regulations causing all sorts of grief.The 402/400 was discontinued after 1972 and the 454 was no longer used in passenger cars after 1976 and not installed in trucks after 1979.In 1983 Chevrolet started to install the 454 into their light and medium duty trucks.

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