1972-1990 Chevrolet Small-Block Engine Overhaul Manual

Contents Chapter 1 Introduction How to use this repair manual 1-1 What is an overhaul? 1-1 Engine identification 1-2 Parts interchangeability 1-6 Buying parts 1-11 Chapter 2 Tools and equipment A place to work 2-1 Tools and equipment 2-3 Fasteners 2-37 Component disassembly 2-41 Gasket sealing surfaces 2-41 Hose removal tips 2-42 Automotive chemicals and lubricants 2-42 Safety first! 2-43 Chapter 3 Diagnosing engine problems General information 3-1 Reading symptoms 3-1 Measuring oil consumption 3-2 Diagnostic checks 3-2 Is the engine worth rebuilding? 3-11 Chapter 4 Preparing for an overhaul Preparing to remove the engine 4-1 Removing the engine 4-2 Removing the external engine components 4-11 Chapter 5 Overhauling the cylinder heads Removing the cylinder heads 5-1 Rebuilding the cylinder heads 5-3 Inspecting the valve springs 5-11 Assembling the heads 5-13 Installing the heads 5-14 Installing the valve train 5-16

Chapter 6 Overhauling the engine block Disassembly 6-1 Cleaning and inspection 6-5 Machine shop procedures 6-17 Choosing piston rings and honing the cylinders 6-19 Reassembly 6-21 Chapter 7 Reassembling and installing the engine Introduction 7-1 Replacing the front transmission seal 7-1 Assembling the engine 7-3 \r\staU\ngthe engine 7-14 Starting the engine 7-15 Breaking in the engine 7-16 Chapter 8 Related repairs Carburetor overhaul 8-1 Distributor overhaul 8-3 Fuel pump overhaul 8-5 Starter overhaul 8-5 Generator overhaul 8-10 Alternator overhaul 8-10 Chapter 9 Improving performance and economy Introduction 9-1 Camshaft selection 9-3 Exhaust modifications 9-8 Ignition systems 9-11 Intake manifolds 9-12 Carburetors 9-14 Making it all work together 9-18 Engine swaps 9-18 Glossary GL-1 Appendix A Booster battery (jump) starting AP-1 B Conversion factors AP-2 C Electrical glossary AP-3 D Understanding wiring diagrams AP-12 Index iND-1

Introduction How to use this repair manual The manual is divided into Chapters. Each Chapter is sub-divided into Sections, some of which consist of con- secutively numbered Paragraphs (usually referred to as "Steps", since they're normally part of a procedure). If the material is basically informative in nature, rather than a step-by-step procedure, the Paragraphs aren't numbered. The first three Chapters contain material on preparing for an overhaul. The remaining Chapters cover the specifics of the overhaul procedure. Comprehensive Chapters covering tool selection and usage, safety and general shop practices have been included. The term "see illustration" (in parentheses), is used in the text to indicate that a photo or drawing has been included to make the information easier to understand (the old cliche "a picture is worth a thousand words" is especially true when it comes to how-to procedures). Also, every attempt is made to position illustrations directly opposite the corresponding text to minimize confusion. The two types of illustrations used (photographs and line drawings) are referenced by a number preceding the caption. Illustra- tion numbers denote Chapter and numerical sequence within the Chapter (i.e., 3.4 means Chapter 3, illustration number four in order). The terms "Note", "Caution", and "Warning" are used throughout the text with a specific purpose in mind - to attract the reader's attention. A "Note" simply provides information required to properly complete a procedure or information which will make the procedure easier to understand. A "Caution" outlines a special procedure or special steps which must be taken when completing the procedure where the Caution is found. Failure to pay attention to a Caution can result in damage to the component being repaired or the tools being used. A "Warning" is included where personal injury can result if the instructions aren't fol- lowed exactly as described. Even though extreme care has been taken during the preparation of this manual, neither the publisher nor the author can accept responsibility for any errors in, or omis- sions from, the information given. What is an overhaul? An engine overhaul involves restoring the internal parts to the specifications of a new engine. During an overhaul, the piston rings are replaced and the cylinder walls are reconditioned (rebored and/or honed). If a rebore is done, new pistons are required. The main bearings, connecting rod bearings and camshaft bearings are generally replaced with new ones and, if necessary, the crankshaft may be reground to restore the journals. Generally, the valves are serviced as well, since they're usually in less-than-perfect condition at this point. While the engine is being overhauled, other components, such as the distributor, starter and alternator, can be rebuilt as well. The end result should be like a new engine that will give many thousands of trouble-free miles. Note: Critical cooling sys- tem components such as the hoses, drivebelts, thermostat 1-1

Haynes Chevrolet engine overhaul manual 1.1 Typical Chevrolet code number locations and water pump MUST be replaced with new parts when an engine is overhauled. The radiator should be checked carefully to ensure that it isn't clogged or leaking; if in doubt, replace it with a new one. Also, always install a new oil pump when overhauling the engine - we recommend against rebuilt pumps. It's not always easy to determine when, or if, an engine should be completely overhauled, as a number of factors must be considered. High mileage is not necessarily an indication that an overhaul is needed, while low mileage doesn't preclude the need for an overhaul. Frequency of servicing is probably the most important consideration. An engine that's had regular and frequent oil and filter changes, as well as other required maintenance, will most likely give many thousands of miles of reliable service. Conversely, a neglected engine may require an overhaul very early in its life. Excessive oil consumption is an indication that piston rings, valve seals and/or valve guides are in need of attention. Make sure that oil leaks aren't responsible before deciding that the rings and/or guides are bad. Perform a compression check (see Chapter 3) and have a leak-down test performed by an experienced tune-up mechanic to determine the extent of the work required. If the engine is making obvious knocking or rumbling noises, the connecting rod and/or main bearings may be at fault. Check the oil pressure with a gauge installed in place of the oil pressure sending unit or switch (see Chapter 3) and compare it to the specifications for the particular engine (see the Haynes Automotive Repair Manual for your vehicle). If it's extremely low (generally, less than 10 psi at idle), the bearings and/or oil pump are probably worn out. Loss of power, rough running, excessive valvu train noise and high fuel consumption rates may also point to the need for an overhaul, especially if they're all present at the same time. If a complete tune-up doesn't remedy the situation, major mechanical work is the only solution. Before beginning the engine overhaul, read through this entire manual to familiarize yourself with the scope and requirements of the job. Overhauling an engine isn't partic- 1.2 Check for a casting number at the rear of the block (arrow) ularly difficult if you have the correct equipment; however, it is time consuming. Plan on the vehicle being tied up for a minimum of two weeks, especially if parts must be taken to an automotive machine shop for repair or reconditioning. Check on availability of parts and make sure that any necessary special tools and equipment are obtained in advance. Most work can be done with typical hand tools, although a number of precision measuring tools are required for inspecting parts to determine if they must be replaced. Often an automotive machine shop will handle the inspection of parts and offer advice concerning reconditioning and replacement. Engine identification Identifying just which engine you have is critical because Chevrolet engines which are very similar in appearance can be quite different in important details. Prior to 1972 on passenger cars and 1973 on light trucks, the Vehicle Identification Number (VIM) only indicates whether the vehicle originally came with a six-cylinder or a V8. Some of these engines can be identified by the decals on the air cleaner or the valve covers. If these markings are missing or you suspect they are incorrect, check for numbers on the engine. Record the VIN number (see illustration) and also the casting number on the rear of the engine block between the distributor and bellhousing (see illustration). Also note the shape of the casting marks on the ends of the cylinder heads (later models don't have these). Using this information, check with your local dealer parts depart- ment or salvage yard for assistance in identification. On 1972 and newer passenger cars and 1973 and newer light trucks, the first step of engine identification is to look at the VIN, because the VIN includes a code letter that indicates which engine the vehicle is equipped with. The VIN plate is located at the left front corner, just inside the windshield on passenger cars or on the door jamb of trucks and vans (see illustrations). 1-2

Introduction CHEVROLET Passenger Cars Example (1972 through 1980 models) Model Year Codes 2 = 1972 3 = 1973 4 = 1974 5 = 1975 6 = 1976 7 = 1977 8 = 1978 9 = 1979 0 = 1980 B =1981 C = 1982 D = 1983 E = 1984 F =1985 G = 1986 H = 1987 J =1988 K = 1989 L =1990 X X XX L S^X XXXXXX Engine Model year code code Example (1981 through 1990 models): X XXX XXX L X BX XXXXXX Engine Model year code code 1972 Code F H J K L R S U V \N C.I. 307 350 350 350 350 400 402 402 454 454 H.P. (130 HP) (165 HP) (175 HP) (200 HP) (255 HP) (170 HP) (210 HP) (240 HP) (230 HP) (270 HP) 1973 F H J K R T X Y Z 307 350 350 350 400 350 454 454 454 (115HP) (145 HP) (190 HP) (175 HP) (150 HP) (245 HP) (215 HP) (245 HP) (275 HP) 1974 Code H J K L R T U Y Z C.I. 350 350 350 350 400 350 400 454 454 H.P. (145 HP) (195 HP) (185 HP) (160 HP) (150 HP) (245 HP) (180 HP) (235 HP) (270 HP) 1975 G H J L T U Y 262 350 350 350 350 400 454 (145 HP) (165 HP) (155 HP) (205 HP) 1976 Code G L Q C.I. 262 350 305 H.P. (165 HP) 1976 (con't) Code S U V X C.I. 454 400 350 350 H.P. (145 HP) (210 HP) 1977 L U X 350 305 350 (170 HP) (210 HP) 1978 H L 350 350 (220 HP) (170 HP) 1979 G H J L 4 8 305 305 267 350 350 350 (2 barrel) (4 barrel) 1.3 Passenger car V8 engine codes 1-3

Haynes Chevrolet engine overhaul manual 1980 Code H J L 6 8 C.I. 305 267 350 350 350 H.P. 1981 H J L 6 305 267 350 350 1982 H J 7 8 305 267 305 350 (fuel injection) (fuel injection) Code H S 6 7 8 G H 6 8 F G H 6 8 198: C.I. 305 305 350 305 350 198' 305 305 350 _ 350** 1985 - ' 305 305 305 350 350 } H.P. (police) 1 [ (fuel injection) 1986 (fuel injection) (police) (fuel injection) 1987 - 1988 Code E F G H Y 8 C.I. 305 305 305 305 305 350 H.P. (fuel injection) (TPI) (4 barrel) (4 barrel) (4 barrel) (TPI) 1989 - 1990 E F8 Y 8 305 305 305 350 (fuel injection) (fuel injection) (fuel injection) 1.3 Passenger car V8 engine codes (continued) CHEVROLET & CMC Light trucks Model Year Codes 4 = 1974 5 = 1975 6 = 1976 7 = 1977 8=1978 9=1979 0=1980 B = 1981 C = 1982 D = 1983 E = 1984 F = 1985 G = 1986 H = 1987 J =1988 K = 1989 L = 1990 Example (1974 through 1980models): XX VXX5XXXXXXX 1—t- Engine Model year code cod* Example (1981 through 1990 models): X X X X XXX L X F XXXXXXX Engln* Model year code code 1-4 1.4 Light truck V8 engine codes

Introduction 1973 Code X Y Z C.I. 307 350 454 H.P. (130 HP) (155 HP) (240 HP) 1974 L U V W Y Z 454 350 350 350 350 454 (245 HP) (export) (2 barrel) (LPgas) (160 HP) (230 HP) 1975 L M U V Y Z 454 400 350 350 350 454 (245 HP) (export) (2 barrel) (4 barrel) (230 HP) 1976 L S U V Y 350 454 400 350 454 1977 L R S U Y 350 400 454 305 454 1978 Code L R S U Y C.I. 350 400 454 305 454 H.P. 1979 L M R S U 350 350 400 454 305 1980 G L M P R S W X 305 350 350 350 400 454 454 400 1981 F G H J L M P W 305 305 305 267 350 350 350 454 1982-1984 Code F H L M P W C.I. 305 305 350 350 350 454 H.P. 1985-1986 F H K L M N W 305 305 350 350 350 262 454 1987 H K M N W 305 350 350 454 454 (TBI) (TBI) (4 barrel) (TBI) (4 barrel) 1988 H K N 305 350 454 (fuel injection) (fuel injection) (fuel injection) 1989- 1990 H K M N W 305 350 350 454 454 (fuel injection) (fuel injection) (fuel injection) 1.4 Light truck V8 engine codes (continued) 1-5

Haynes Chevrolet engine overhaul manual Parts interchangeability A lot of time and money can be saved if you know which parts are interchangeable between your engine and those available on the used market and in wrecking yards. There is considerable interchangeability within the Chevrolet small block and big block families. However, few parts from one family are usable in the other; about the only notable exception is the distributor. Due to the vast number of Chevrolet V8 engines produced since 1955 in many versions, a complete and comprehensive guide would require several volumes the size of this book. Most wrecking yards have interchange manuals that provide a wealth of information for parts swapping. The following information provides a basic overview, and does not cover every possible combination of parts. We will treat the small block and big block engines sep- arately; refer to the appropriate Sections based on the engine family you are working on. Small block V8s Small block Chevrolet engines were produced in the largest numbers of any automotive powerplant in history. Beginning with 1955 models through the present, they have been built in 262, 265, 267, 283, 302, 305, 307, 327, 350 and 400 cubic inch versions. The different displacements are obtained by combining several bores and strokes in various combinations: Bore (inches) 3.671 3.750 3.500 3.875 4.001 3.736 3.876 4.001 4.001 4.126 Stroke (inches) 3.10 3.00 3.48 3.00 3.00 3.48 3.25 3.25 3.48 3.75 Displacement (cubic inches) 262 265 267 283 302 305 307 327 350 400 Displacement table Camshafts Camshaft specifications vary considerably among different model years and horsepower versions. The camshaft specifications should closely match the rest of the engine to assure the best performance, driveability, economy and lowest emissions. Except for 1987 and newer models with roller lifters, camshafts are interchangeable from one year or model to the other, since the journals have the same diameter and spacing. Note: On 7955 and some 1956 265 engines, the rear journal of the camshaft must be notched to assure an oil supply to the valve gear. Chevrolet factory camshafts are available: for hydraulic, solid and even roller lifters (on 1987 and later models) Fac- tory roller cams and lifters can only be installed in 1987 and newer blocks that were designed for them. Camshafts and non-roller lifters should always be replaced togethe1 as a set. It is often difficult to determine which camshaft is installed in a particular used engine before it is taken apart. Even after the camshaft is removed, casting numbers are unreliable for identifying specific grinds. Although used camshafts can be installed in another engine if the lifters are reinstalled on the same lobes, we recommend new camshafts and lifters when replacement is necessary. Cylinder heads Except for a few aluminum heads found on racing Corvettes around 1961, virtually all factory made small block heads are made from cast iron. Cylinder heads are available in a wide variety of valve sizes, combustion chamber volume, spark plug type and port size. Pre-1959 heads can be identified by the spacing of the valve cover bolts. On 1959 and later heads, the bolt holes are directly opposite each other (see illustration); on early 1-6

Introduction 1.5 Most 1959 and later cylinder heads have valve cover bolts that are directly opposite each other models the spacing was staggered. The latest heads have valve covers with four bolts running lengthwise down the center. Valve covers must be selected to match the type of cylinder head. All 1955 through 1968 heads lack mounting bolt holes on the ends for accessories such as power steering pumps or alternators (see illustration). Later heads can be used on early models, but not vice versa. Early in 1971 Chevy changed from straight to slant spark plug locations. The plug design was also changed from flat seat and washer type to tapered seat type. These heads have larger combustion chambers for lower compression. Several valve sizes were used over the years. Early 265 and 283 heads used 1.72 inch diameter intake and 1.50 inch exhaust valves. Later high performance 283 heads have 1.94 inch intake valves. For high performance use, the "202" or "fuelie" heads are very popular. These have large ports and 2.02 inch diameter intake valves and 1.60 inch exhausts. They were used mostly on Z28s and Corvettes with 302, 327 and 350 fuel injected and high performance carbureted engines. The present part number for these is 3987376, superseding 3853608, 3958604 and 3928445. Later angle-plug high performance heads go by part number 3965742. A 1976 head with large spring seats is number 336746. Pre-1974 heads are not designed for unleaded or low-lead fuel and should have special valves and hardened valve seats installed to reduce valve reces- sion on today's fuel. Production aluminum heads were introduced on 1986 Corvettes. In 1988 they were updated with larger "D" shaped exhaust ports. If these heads are used, be sure to match the intake and exhaust manifolds to the ports. Due to the low octane fuels currently available, the compression ratio should be limited to about 9 or 9.5 to 1. Many high performance heads have small combustion chamber volumes and high dome pistons that raise the compression to 10.5 or higher. Try to find heads from an 1.6 1969 and later heads have bolt holes (arrows) for accessories engine that did not have extremely high compression and use flat top pistons. Heads are available in both standard small port and high performance large port versions. Using an intake manifold gasket, compare the size of the ports in the heads and intake manifold to ensure a match. Compare the exhaust manifold mounting bolt pattern to the exhaust manifold/header you intend to use; there are different versions. Always check carefully for valve sizes, combustion chamber volume, exhaust manifold and spark plug type and port size when comparing cylinder heads to obtain the correct ones. Look for cracks and deep-seated valves and reject any worn out or damaged heads. Whenever possible, obtain replacement cylinder heads in matched pairs to ensure they are the same. Intake manifolds There are a great many choices in intake manifolds. The factory has offered two-barrel and four-barrel carburetors, dual four-barrel carburetors, Rochester fuel injection (from 1957 through 1965), throttle body fuel injection and port injection. If you are working on a fuel injected model or restoring a vehicle to original condition, an identical part must be obtained. We will not go into detail on fuel injected or multi- carb models, since the choices are limited. However, for most applications using a single carburetor, several types of manifolds will work satisfactorily. Although the bolt pattern is the same on all years, early models have an oil filler tube; later models have filler caps in the valve covers. Be sure to use the correct version. For low-performance work, a cast-iron manifold with a two-barrel carburetor will suffice. Early models generally have smaller carbs and ports than later models. Also, the automatic chokes can be activated by exhaust manifold tubes or choke stoves mounted next to the carburetor. A single four-barrel carburetor manifold works best for most applications. These are available with mounting provisions for Carter, Rochester and Holley carburetors. Early 1-7

Haynes Chevrolet engine overhaul manual 1.7 If you're swapping manifolds, make sure there are provisions for all your vacuum fittings (arrow) models and/or lower horsepower engines can use manifold part number 3888886 with a small Carter or Holley four-barrel. From 1966 on, most four-barrel models used Rochester Quadrajets on a manifold with part number 3987361. Relatively few aluminum four-barrel manifolds were installed at the factory. Exchanging a cast-iron manifold for an aluminum one is an easy way to shave weight off the front end of a vehicle. For high-performance street use, the factory aluminum high-rise is hard to beat. It mounts a square-flange Holley four-barrel or Carter AFB and goes under part number 3958627 superseded to 3972114. Always compare the port sizes of the heads and manifolds by holding a gasket up to both openings. For optimum performance, the sizes must match. Larger ports favor high rpm and larger displacements. Small ports tend to improve low rpm torque and driveability. On 1973 and later models, look for Exhaust Gas Recir- culation (EGR) valve provisions. Always compare the old and new manifolds to determine if sufficient vacuum fittings are present (see illustration). Exhaust manifolds The choice of exhaust manifolds is limited to a few basic designs; none of these are exceptional from a performance standpoint. Many enthusiasts convert to tubular headers if they are looking for more performance. Generally, the "ram's horn" shape manifolds used on early Corvettes and high-performance passenger cars pro- duce more power than the log shape designs. However, clearance between body and frame determines which exhaust manifolds can be used in a given situation. There are several types of exhaust outlet flanges from 2 to 2 1/2 inches in diameter, using both two and three studs. Heat risers or EFE valves, if used, must fit the manifold cor- rectly. Also, accessory mounts and the length and angle of exhaust outlet must match the engine and vehicle. Be sure to check the number of cylinder head-to-manifold mounting bolt holes; these vary on different models. 1.8 Crankshafts with a two-piece rear main oil seal look like this from the rear Crankshafts There are a vast number of different versions of small block Chevy crankshafts. Over the years, several different stroke lengths and journal diameters have been introduced. Unique among them are the 400 c.i. models; these stand alone and are not interchangeable with any others. Also, 400 crankshafts are externally balanced and must be used with flywheels/driveplates and harmonic balancers designed for the 400. Journal diameter remained the same on 265, 283, 327 and early 350s through 1967. Stroke was the same on 265 and 283 models, but 327s have a longer stroke. Beginning in 1968, the journal diameters were increased and these cannot be swapped with earlier models. High-performance models used forged crankshafts with Tuftrided journals (a special hardening treatment) and lower performance models have cast cranks. Forged crankshafts can be used in low performance models, but cast cranks should not be used in high-revving performance engines. Generally, the newest or highest performance version with a given stroke will be the best choice. Beginning in 1986, the rear main oil seal design was changed from a two-piece to a one-piece seal. The flywheel mounting flange on the crankshaft was also modified to be compatible with this change (see illustration). Be sure to use all the components from one type together. Connecting rods There are three basic sizes of small block V8 connecting rods. These are found in 1955 through 1967, 1968-on (except 400 c.i.) and 400 cubic inch models. All small blocks, with the exception of the 400 cubic inch version, use the same length connecting rods. The rods in 400 c.i. models are 5.565 inches center-to-center while all other rods are 5.700 inches center-to-center. However, models prior to 1968 have smaller diameter crankshaft journals and therefore are not interchangeable with later models. 1-8

1972-1990 Chevrolet Small-Block Engine Overhaul Manual

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