Chevrolet Performance Parts

With GM’s legendary Fast Burn cylinder heads and 383 cubic inches, the ZZ383/425 delivers incredible torque with smooth, linear delivery. If you’re looking for a small-block package that delivers big-block power, then you’ve found it. 425 horsepower at an incredibly low 5400 RPM, and 449 ft.-lbs. of torque at 4500 RPM make this the ideal hot street engine.
Keys - scperformanceeng, gmperformanceeng, or gmgoodwrencheng for SC, GM, or Goodwrench engines. Use allengine for a complete list of all three.

WEB SITE NAVIGATION INFORMATION

GM and Chevrolet part prices are in the Price & Parts search. Keys are to be used with the Price & Parts Search. Enter a Key, part number, GM, SC, or a key word, like 502, into the Price & Parts search to see if we have it on our site. Use GM for a list of both GM and GMPP parts. Use SC for a list of all Chevrolet exclusive parts. Aftermarket company prices are on downloadable Price Sheets or on their pages. The Page Search is for searching the pages of our Web site. More information on this is on our help page.

383CI STROKER ENGINES NAVIGATION

GMPP HT 383 Main Page	GMPP HT 383 Pictures
GMPP HT 383 Parts List	GMPP HT 383 Partial Engine
GMPP ZZ383/425 Main Page	Chevrolet Premium ZZ383/425 Main Page
Chevrolet ZZ450 Main Page	Chevrolet ZZ450 Pictures
Chevrolet The SBC 50th Anniversary.	Chevrolet ZZ383-500
Chevrolet ZZ383-500A Pictures	Chevrolet ZZ383-500 Pictures
Chevrolet ZZ383-500 Options Photos	Chevrolet ZZ383-500 Parts Photos

We have more GM and Chevrolet Performance Engines available. We have more GM Stock Replacement Long-block Goodwrench Engines available. We have more “Gen 3” and “Gen 4” Design Engines available. (LS1, LS2, LS6, LQ4, LS7)

ZZ383/425 DESCRIPTION

ZZ383/425 Hot Street Engine P/N 12498772 With GM’s legendary Fast Burn cylinder heads and 383 cubic inches, the ZZ383/425 delivers incredible torque with smooth, linear delivery. If you’re looking for a small-block package that delivers big-block power, then you’ve found it. 425 horsepower at an incredibly low 5400 RPM, and 449 ft.lbs. of torque at 4500 RPM make this the ideal hot street engine. The excellent air handling and combustion characteristics of the Fast Burn cylinder heads combined with the ZZ383/425’s 3.800” stroke, make this engine the benchmark against which all other 383 inch small-blocks should be measured. And it’s tough, too. The 4340 nitrided and induction hardened crank and unique forged PM rods see to that. The 9.7 to 1 compression ratio ensures that the ZZ383/425 is 92 octane pump gas friendly. The ZZ383/425 gets a stout .509/.528 lift steel camshaft with 222/230 duration at .050 lift. Hydraulic roller lifters and GM’s time tested 1.5 to 1 roller rocker arms round out the valve train. And, of course, it has the Fast Burn head’s lightweight stainless steel valves and retainers for reliable performance at extended RPM. GM’s testing was completed using a GM single plane intake, P/N 12496822 and a 750 CFM Demon carburetor with mechanical secondaries. Test header specs are: 1-3/4” primaries, 33 inches long with a 4-inch collectors. GM dual plane intake P/N 12366573 may be used for hood clearance on the ZZ383/425, but it results in a decrease in peak horsepower of approximately 15-20 horsepower.	Now Available! We just got our first shipment in. 03-29-2004
Type the part number in the Price Search for price.
ZZ383/425 Graph" width="660" height="494">

ZZ383/425 TECHICAL INFORMATION

Horsepower:	425 @ 5400 RPM	Torque:	449 @ 4500 RPM
Max. Rec. RPM:	6,000	Comp. Ratio:	9.7:1¹
Displacement:	383 ci	Bore x Stroke:	4.00” x 3.80”
Block:	88962516 Four bolt main, cast iron	Firing Order:	1-8-4-3-6-5-7-2
Con. Rods:	12497624 PM 5.7” PM Steel	Rocker Arms:	12370838 1.5 ratio roller rockers kit
Pistons:	12499103 High Silicon Aluminum, .005 O/S	Piston Rings:	12499107 .005 O/S
Camshaft:	12370846	Lift:	0.509” I, 0.528” E
Duration:	222° I, 230° E @ .050” Lift	Centerline:	112°
Valve Lash:	Zero	Timing Chain:	14088783 8 mm single roller design.
Cylinder Heads:	12464289 Fast Burn	Volume:	62 cc
Head Gasket:	10105117 (.028” compressed thickness)
Intake Valves:	12555331, 2.00” dia.	Exhaust Valves:	12551313, 1.55” dia.
Valve Springs:	12551483	Oil Pan:	5 quart with new filter.
Oil Pres. (norm):	40 psi @ 2,000 RPM	Oil Filter:	UPF1218 ACDelco Ultra Gold
Spark Plugs:	R44LTS or R42LTS for racing	Fuel:	Premium 92 Octane or greater
Partial Engine:	12499106	Damper:	12498008

Crankshaft:	12489436 4340 steel alloy (forged), one piece rear seal design, 3.8” stroke, 2.45 main journals/ 2.10” rod journals (standard 350 engine), main and rod journals are fully radiused, number 1 & 4 crank pins hollowed, cross drill oiling, rod and main oil chamfered, 3.00” flange bolt circle, nitride treated, and main bearing bolt torque.
Intake Manifold:	None supplied with this crate engine.
Water Pump:	None supplied with this crate engine.
Ignition Timing:	32° total @ 3000 RPM with vacuum advance line disconnected and plugged. This setting will produce 32° of total advance at wide open throttle (WOT).
Flexplate:	14088765 12-3/4” outside diameter, 153 tooth, 10.75” bolt pattern.
Technical Notes:	1 - GM recommends a Demon 750 CFM or Holley 750 CFM carburetor for ZZ383 applications. 2 - In 2004 GM redesigned the pistons and rings and they are .005" over sized now. This was done to better improve piston to cylinder wall clearance. The .005” O/S pistons and rings are the recommended standard size for all second design 383 ci engines. The first design ring and piston sets were: [Rings - 12522848 std. 4.00”, Pistons - 12489437 std. 4.00" (piston & pin set).]
Note¹:	The GMPP catalog states that the compression ratio is 9.1:1 which is wrong. The compression ratio is 9.7:1 for the ZZ383/425 where the compression ratio is 9.1:1 for the HT 383 which uses a thicker head gasket.

ADDITIONAL PARTS THAT WILL WORK WITH THE ZZ383/425

Flywheel: Like all small-block V8 engines produced since 1986, the ZZ 383/425 crate engine has a 3.00” diameter flywheel flange bolt pattern. Small-block V8 engines produced from 1958 through 1985 had a 3.58” diameter flywheel flange bolt pattern. This change in bolt circle diameter was made to accommodate a leak-resistant one piece rear main seal.

Pilot Bearing: You must install a pilot bearing in the rear of the crankshaft if the engine will be used with a manual transmission. The pilot bearing aligns the transmission input shaft with the crankshaft centerline. A worn or misaligned pilot bearing can cause shifting problems and rapid clutch wear. A roller pilot bearing P/N 10461685 is recommended for this engine. This heavy duty bearing adds an extra margin of reliability to a high performance drivetrain.

Starter: The ZZ383/425 does not include a starter. The starter must be matched to the flywheel or flexplate diameter when installing the ZZ383/425 engine. Small diameter flywheels are 12-3/4” and have 153 teeth. Large diameter flywheels are 14” and have 168 teeth. This difference in flywheel diameter requires two different starter housings. Starter noses used with 14” diameter flywheels have two offset bolt holes; starters used with 12-3/4” flywheels have bolt holes that are straight across from each other.
Starters that can be used with the ZZ383/425 are: P/N 10496870, 1876552, 14097278, 14097279, 10455709, 9000852, 14037733, and 12338064.
Note - Chevrolet starter motors use special shoulder mounting bolts which register the starter on the block.

Carburetor/Air Cleaner: A 750 cfm four-barrel carburetor with either mechanical or vacuum operated secondaries and electric choke is recommended for the ZZ383/425 engine.
A foam or paper element, low restriction air cleaner should be used. The fuel mixture distribution can be upset if no diffuser is used, causing poor power and misfiring at high engine speeds. Always check for adequate hood clearance when installing a new air cleaner. GMPP has two chromed, 14” diameter, open element air assemblies for single four-barrel carburetors. P/N 12342079 has a plain top, and P/N 12342071 has a Chevrolet logo. Both of these are supplied with a 3” tall filter element P/N 6421746 (AC P/N A212cw). A taller 4” element is available as P/N 8997189 (AC P/N A698c).

Fuel Pump: The ZZ383/425 crate engine does not include a fuel pump. The fuel system must be capable of supplying adequate fuel volume at a minimum of 6 psi pressure when the engine is operating at wide open throttle (WOT). A high volume in-line electric fuel pump is available from GMPP P/N 25115899. This heavy duty pump flows 72 gallons per hour at 6-8 psi outlet pressure.

Spark Plugs/Spark Plug Wires: The ZZ 383/425 crate engine comes with spark plugs P/N 5613611 (AC P/N R44LTS). If you are installing the engine in a vehicle originally equipped with a small-block V8 with HEI ignition, standard replacement spark plug wires can be used. High performance 8 mm diameter wire sets with Chevrolet Bow Tie logo or GMPP logo are available from GMPP for custom installations. The GMPP logo wire sets are available as P/N 12361056 (135° spark plug boots) and P/N 12361057 (90° spark plug boots). The Chevrolet logo wire sets are P/N 12361050 (135° spark plug boots) and 12361051 (90°spark plug boots). The 135° spark plug boot set is recommended for routing the spark plug wires over the valve covers. The 90° spark plug boot set is recommended for routing the spark plug wires under exhaust headers. For extended highway use, you may want to upgrade spark plugs to 41-942 Dual Platinum P/N 25164048.

Rocker Covers: The ZZ383/425 comes equipped with black stamped steel, center hold-down rocker covers. A black composite center hold-down bolt LT4 type rocker cover is available (P/N 12552321 LH and P/N 12552322 RH). Also chrome center hold-down bolt rocker covers with a red chevrolet Bow Tie logo are available (P/N 12355350 LH and RH). The Fast Burn Heads will also accept the older “Rim Mount” style valve covers, for those that prefer those to the newer style “Center Bolt” valve covers, and no adapter is needed because they designed for ether style valve cover to bolt right on.

Still Not Good Enough: Our Race Shop can customize the ZZ383/425 to fit your needs all the way to a complete Turnkey engine ready to drop in. Our Race Shop is in-house for maximum quality control. We do not farm out our engine building to a third party like most on-line parts stores do. Call and talk to one of our Counter Sales people for details and warranty information on this engine. A complete price quote including shipping cost can be put together for you if you call and are seriously considering buying.