Engine and Driveline
Engine/Transmission/Rear End Housing Overhaul
This program will not cover the technical aspect of an engine, transmission, or rear end rebuild. There are literally hundreds of books on the market on how to rebuild and/or hot rod your engine and transmission. Odds are pretty good you will want to freshen up these major components and replace gaskets, seals, etc. and inspect/replace internal components as necessary for reliability. I do not mean to imply that internal pieces like the crankshaft, connecting rods, pistons, piston rings, camshaft, etc. are not important in an engine rebuild but those components are not going to be seen by judges or your peers.
Suggested specialty engine rebuilding books such as How To Rebuilt the Small-Block Chevrolet by Larry Schreib and Larry Atherton for your small block V8 or How To Rebuild the Big-Block Chevrolet by Toney E. Huntimer; both available CarTech publications.
If your engine block needs to be bored due to cylinder wall wear, so be it. Nobody is going to see a +.030 bored cylinder and +.030 oversize pistons and rings. Same for the crankshaft or camshaft; if either needs to be replaced or the crankshaft turned due to wear, neither are visible once the engine is assembled. I am not saying to skimp on components here but searching for that NOS L78 or LS6 mechanical lifter camshaft is not something one really needs to do, even for a Concours restoration.
One thing you should alert your machine shop about is the importance of the engine assembly plant stamp on the engine pad and possibly the partial vehicle identification number (VIN) stamp if it is on the engine pad. If your engine block needs to have the deck surfaced to fix any warpage or wear, the engine pad must, at all costs, be spared this machining. When you are working with an original-to-the-car engine, it is the only engine that car came with and these identifying numbers/letters are your only real proof the engine is original to the car. It may seem extreme to some, after all, an engine is just an engine, right? For your daily driver or weekend cruiser, that may be. But in the Concours restoration world having the original engine can mean, literally, thousands of dollars in the car’s value.
If your selected machine shop cannot service the engine block without obliterating these stamps, find another machine shop. Resist the urge to give in and let them “restamp” the engine pad. Chances are very slim they will have the correct fonts on their stamp dies for both the Tonawanda engine stamp information plus the correct, and different, stamp dies for the particular final assembly plant and the partial VIN information. If the machinist messes up the stamping, and most will not survive good scrutiny, your car will forever be suspected of having a restamped engine pad and could cost you not only in judging but most certainly in resale value should you ever decide to sell the car.
Often the engine suffix code is applied at the Tonawanda, N.Y.
engine plant like this example that may appear once the block has
been hot-tanked for cleaning.
Sample engine plant stamp from the Tonawanda Engine Assembly
Plant showing the engine plant’s letter designation, assembly date,
and three-letter suffix code identifying the horse power rating of
the engine and the transmission type. The second stamping is from
the final assembly plant indicating the sequence number of the car
the engine was installed in. (Photo Courtesy LS6 Registry).
Chevrolet Engines were built at the Flint. MI. and Tonawanda, N.Y. engine assembly plants by the thousands each year. While quality control was present, it is important to remember these engines were built for the masses and, to a certain degree, reliability and a long life. Engine blocks were stamped with the engine assembly plant letter, “T” for the Tonawanda engine plant or “V” for the Flint engine plant (Flint V8 engines built before 1967 used the letter “F”), a 4-digit assembly date depicting the month and date (such as 1025 for October 25, 0123 for January 23, etc.) and a 1-, 2-, or 3-letter suffix code to identify the advertised engine’s horsepower rating, and the transmission type the engine was to be fitted with.
The basic engine assembly and components themselves were the same regardless of transmission type but would be fitted with either a flywheel and manual transmission pilot busing in the crankshaft or with a flexplate for an automatic transmission car. The final assembly plant also used the transmission information to determine which components they would install on the engine such as the carburetor.
In some years even the Chevrolet car line made a difference in the suffix code. A 1969 396 cubic inch displacement engine with manual transmission destined for a Chevelle has a different suffix code (JC) than the same engine/transmission combination destined for a Camaro/Nova (JF). Some late 396 engines had their bore increased to display 402 cubic inches in preparation for the 1970 model year. Due to some production problems these engines were installed in late 1969 Chevelle and Camaros but used a 3-letter suffix code. For example, where an early engine would be stamped with a JC engine/transmission code the late engine would be stamped CJC.
In late 1969 and into 1970 the 402 cubic inch displacement engine with manual transmission destined for Chevelles and Novas got the suffix code CTX while the Camaro got the suffix code CJF. Why is this important? If your original engine is long gone or beyond repair, finding a period correct replacement is an alternative and the suffix code can assist you in getting the “correct” engine for your Chevelle.
Be cautious of engine stamps. There are two schools of thought here, maybe more. One is that it is alright to restamp your original engine block with the same information it was born with in the event the stamps are destroyed during machining. The problem is there is no way to prove or disprove whether the original engine block was restamped or if the restamp was done on a “date-correct” engine block. A second thought is it is alright to stamp an engine with anything you want (or need) to make it appear correct. This second one I still cannot get my head around. The engine obviously is not original to the car and any attempt such as this is tantamount to fraud. Whether you inform a potential buyer or not is beside the point; what is that potential buyer going to tell the next buyer?
Often people will use engine assembly plant marks on the engine pad, more commonly known as “broach marks,” as a clue to the engine being original, or not decked and restamped. A broach cutter is a toothed tool used to remove rough casting material. Two broach cutters were used during the engine cleanup after casting. One cutter broaches (machines) the oil pan rail and upper half of the main bearing bores. Another is a “V” shape and is used to machine the engine deck and top horizontal surface of the engine block. As these cutters wore, they would leave slight front-to-back scores in the engine block that are visible on the engine pad – “broach marks.” Fresh blades in the tool left hardly any broach marks at all; as the blade wore, the broach marks became more visible until the blades needed to be changed. Most machine shops will use a rotary grinder to resurface the engine block’s deck area. These will leave a swirl mark on the engine pad making it pretty easy to identify if the engine block has been resurfaced this way.
An alternative to the original engine is a warranty replacement engine. These were used in either short block or long block form depending on the amount of damage to the original engine. Warranty engines are not uncommon today and there is no shame in using one but it still may affect the overall perceived value of the car unless you happen to have paperwork showing that engine with its serial number was, indeed, used to replace the original engine in your car.
A Chevrolet warranty engine will have its own serial number stamped on the engine pad. This will begin with the letters “CE” meaning Chevrolet Engine. Following the CE is a 6-digit number identifying when it was used and the serial number of the engine itself. A sample would be CE959822 where “C” is Chevrolet, “E” is engine, “9” is the calendar year the engine was assembled (1969), and 59822 is the engine serial number. The Tonawanda engine plant was assigned the number range of 50000 to 79999 for each calendar year; Flint V8 engine plant was assigned the number range of 20000 to 49999. In the event more replacement engines were required the letter “X” was added to “CE” and numbering started over at the beginning such as CEX50001. Warranty engines will also normally have a stamp on the starter mounting pad with the engine plant letter and the date such as T099 for Tonawanda engine plant, September 9 (099). Naturally, if you find a warranty engine block, it should be dated after your car’s build date. One cannot have a warranty engine dated in 1970 for a 1971 or 1972 Chevelle and have it appear to be legitimate.
A typical Chevrolet Engine warranty replacement engine stamp.
Another thing to look for is the casting/stamped dates of the components if you are looking for replacements. All major components have a casting date or the date of manufacture is stamped on the piece. The engine blocks, cylinder heads, exhaust manifolds, etc. would not all be cast on the same day and fitted to a particular engine. Each piece would be cast in their respective areas, machined separately, and joined at some assembly point. Some components assembled at the engine assembly plants would come from outside sources such as water pumps, starters, distributors, etc. and would typically have earlier assembly dates than the assembled engine itself. See Appendix C - Engine Assembly Process for a more detailed look at this aspect.
Casting dates are generally in the format of a letter for the month, A through L for January through December, a 1- or 2-digit number for the day of the month followed by a 1- or 2-digit number for the year. Many pieces use “70” for 1970 so it is not confused with “7” for 1967. Other components like distributors, starters, etc. with a stamped assembly date uses the letters from A through M omitting the letter “I” as it can be confused with the number “1.”
Normally, all the peripheral components assembled at the engine plants should be dated BEFORE the engine build date. Components used at the final assembly plant to complete the engine may be dated later than the engine build date since they come from a different supplier, but it is not too common and should not be a lengthy time. Items such as starters, A.I.R. equipment, carburetors, and the like may be a few days later than the engine build date but certainly not weeks or months later.
The same can be said for the engine itself and major drive line components. They should all be dated prior to the car’s build date. How much prior? Anything from a few days to a couple of weeks typically is not questioned but some have been documented to be as much as 3 or 4 months prior to the car’s build date.
