Chevrolet - GMPP ZL-1 ALUMINUM BIG-BLOCK BARE BLOCK
     Based on the original tooling, the new/old ZL-1 is cast from 356-T6M aluminum alloy and tips the scales at a scant 110 pounds. It’s dry cylinder (cast iron) liners are bored to 4.250-inch diameter, that can be bored to 4.300”.
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 ZL-1 ALUMINUM BIG-BLOCK BARE BLOCK DESCRIPTION
12370850
     Chevy’s ZL-1 aluminum big-block is back--and it’s better than ever! Introduced in 1969, the original ZL-1 was one of Chevrolet’s rarest production engines. Now the improved and updated aluminum ZL-1 block is be available as P/N: 12370850.
     Based on the original tooling, the new/old ZL-1 is cast from 356-T6M aluminum alloy and tips the scales at a scant 110 pounds. It’s dry cylinder (cast iron) liners are bored to 4.250-inch diameter, that can be bored to 4.300”. Its bottom end is bolstered with new four-bolt splayed steel main bearing caps, with splayed outer ball-tip studs.. All five main caps are accurately located and held in place with dowel pins, and the rear cap uses an early-style two-piece rear seal. Screw-in aluminum water-jacket plugs with O-ring seals add reliability.
     The reborn ZL-1 block has provisions for both a dry-sump or regular oil pump systems and a mechanical fuel pump. The lightweight big-block is engineered to produce up to 800 hp with reliability, and it’s aimed at vintage Can-Am racers, street rodders, nostalgia drag racers, and ZL-1 enthusiasts. All Gm performance cylinder heads will fit this block and it only weighs 110 lbs. The maximum stroke is 4.375".
     This block includes screw-in freeze plugs with o-ring seals, and a two-piece rear seal.
ZL-1 The new ZL-1 aluminum block (PN12370850) weighs less than 110 pounds. The dry cylinder liners are bored to 4.250-inch diameter. The ZL-1’s bottom end is upgraded with four-bolt steel main bearing caps with splayed outer studs.

 SPECIFICATIONS:
Block Material:
Cylinder Wall Type:
Deck Height:
Cylinder Bore Range:
Cap Bolts:
Cap Material:
Crankshaft Journal Dia.:
Oil Sump Type:
Crankshaft Seal:
Design Max. Stroke:
Weight (bare):
Intended Usage:
Fuel Pump Boss:		 Aluminum
Siamesed
9.800”
4.300”
Splayed, 4 Bolt
8620 Steel
2.75”
Wet or Dry
2 Piece
4.375”
110 lbs.
Street - Modified
Has fuel pump Boss
Non-Standard Parts Required Special Features:
 This is an improved ZL1 block good for 650 HP.