Читать книгу Ford FE Engines - Barry Rabotnick - Страница 8
ОглавлениеWe now have our engine block taken down to its bare essentials: a casting without any parts bolted to it. This is the point where we can decide if it is truly a good candidate to move forward with. A few fairly simple inspections and we are off to the machine shop, where things will get a lot more intensive.
As with other processes throughout the build, you can do this work in many ways, depending on your experience, the tools on hand, your budget, and your desired results. Plenty of engines have been successfully rebuilt with the most basic of tools, done completely in a home garage. Just do not expect such a low-budget package to compete with a professionally machined and reworked combination in terms of power or longevity. Keep your expectations in line with your abilities and your finances and you will be happy with the end result.
When we inspect a block before machining, we are usually looking for damage that cannot be repaired or cannot be repaired at a cost that can be justified. The cost versus value is very different depending on a number of factors.
Common issues include the need for cylinder sleeves due to excessive wear or physical damage. You may also find cracks from freezing or from prior component failure. Significant corrosion damage is possible in certain engines, such as raw water–cooled marine applications or castings that have sat outside for an extended time. Damaged bolt hole threads are common.
A common 360 or 390 block will justify only modest work before you reach its current $200 or $300 replacement value, which is maybe a single sleeve. A 427 block will almost always get repaired; their multi-thousand-dollar value can justify extensive work. If you are working with an original “numbers-matching” combination, you will do whatever it takes to retain that block because of the value it adds to the car.
Basic Block Dimensions
All Ford FE engines share many common characteristics. The nominal deck height as measured from the main bearing center to the cylinder head mounting surface is 10.17 inches. Blocks can be identified from there using a couple external cues, the casting numbers, the date codes, and the bore diameters.
Very early blocks have a different cam mounting and thrust control method. They can be converted to the later style with a little work, but are usually not the best candidate for normal use unless you have all the parts and the need for earlier casting numbers.
Critical Inspection
Basic bore diameter is a quick identifier of an engine block and can be measured with a dial caliper. Precision is not required for block identification, so there is no need to be concerned about to-the-thousands accuracy. A dial caliper is perfectly fine for this task.
Basic bore diameter is a quick identifier, and can be done with a dial caliper. We are seeking only general sizes here, so to-the-thousandths accuracy is not required at this point. A 352 engine starts out life with a 4.00-inch bore, whereas a 360 or 390 begins at 4.050 inches. If your engine block is under that 4.05-inch size, it’s not a 390.
All the 360 and 390 blocks are between 4.050 if standard and 4.110 at .060 over. We generally try to avoid anything beyond 4.090 (.040 over). The sonic test detailed in a subsequent paragraph will demonstrate why. Most FE blocks being built will be either 390- or 360-based. We covered block identification in some detail in chapter 1, but some things merit repeating.
When checking casting codes for FE motors, casting numbers are more useful for telling you what you don’t have versus what you do have. The first two characters in Ford casting numbers represent the decade and year; in the case of the FE, being primarily manufactured in the 1960s and 1970s, the letter “C” represents the 1960s, and “D” the 1970s following Ford’s numbering system. Example: C8 is 1968, D2 is 1972, etc. Something with a D2TE-xx or a C4AE-xx number is obviously not a 428 since those were made from 1966 through 1970. When it exists, the date code is cast below the oil filter pad. This code provides exact casting date information for the numbers-matching folks.
A 428 begins life at 4.130-inch diameter. After 40 years its pretty safe to assume that if somebody is selling a supposedly standard-bore 428 with fresh machining, he is trying to push a .080-over 390 off on you. Stay away; the cylinder walls will often be tissue-paper thin.
A 428 block is often identifiable by a letter “A” or “C” that appears hand scratched in the bellhousing area.
A 427 block is generally out of the context of this book, but with cross-bolt mains and a 4.23 bore they are easily identified. It is fairly common to see the numbers “66-427” cast into a common 390 block; don’t get too excited if you see this.
A 428 block can also be identified by the numbers “428” cast into the floor of interior water jackets below the center freeze plug or below the front or rear water openings to the heads.
Casting numbers are more useful for exclusion than for true identification. The first two characters in Ford casting numbers represent the decade and year in which the casting was released; C8 is 1968, D2 is 1972, etc. A “T” in the third position indicates that the item was initially designed for a truck application, while an “A” means it was originally designed for passenger car use.
Something with a D4TE-xx or a C4AE-xx number is probably not a 428 since those were made from 1966 through 1970, and never installed in trucks. There is often a date code cast below the oil filter pad that provides exact casting date information for the numbers-matching folks.
All FE engines, with very rare exceptions, use the same main bearing diameters, the same cylinder head bolt patterns, the same cam tunnel diameters, and similar bolt holes everywhere on the block. This means that almost every part can be transferred from one block to the other as long as you pay proper attention to things such as valve diameters against cylinder bores.
Fixes for the Factory Block
The factory FE Ford engine block is a very robust design, noted for its durability. Most damage to a factory FE block is related to normal wear or abuse/neglect and can be readily repaired in a well-equipped machine shop. Our initial steps with the block are focused on inspection, making certain that the block is usable and repairable. You want to minimize the possibility of investing a lot of money into a part that cannot be run.
Common damage includes cracks caused by freezing, stripped-out bolt holes, split or scored cylinder walls, and corrosion from sitting in an uncontrolled environment. Most of these issues are repairable within the limits of financial necessity, although a catastrophic failure will occasionally render a block worthless for most folks.
The first step in finding flaws and preparing for reworking the block is a thorough cleaning. Depending on your budget there are a few ways to get the job done. A really low-budget effort might be nothing more than a pressure wash and a lot of scrubbing. But to do the job real justice, we use a “shake and bake” process that involves heating the casting up to burn off any accumulated oil, grime, and paint, followed by an abrasive media in a tumbler that brings the block to a new-casting finish level.
There are three notable variations in main webbing. The aforementioned 427s with cross bolts fall outside my context here. But we still will often see single or double webbing in the main saddle areas on common blocks. The double-web blocks are stronger, and are used in 1968-and-later 428s, including the Cobra Jet, along with many later truck applications. Visual identification is easy once the pan is removed. Compare this example to the single-web block in the top image.
Common cylinder block damage includes cracks caused by freezing, stripped-out bolt holes, split or scored cylinder walls, and corrosion from sitting in an uncontrolled environment. The cylinder walls in this example are showing a fair amount of corrosion, which can be repaired by boring, honing, or in extreme examples, re-sleeving.
Once cleaned up, preferably through a professional process of heating the block to burn off gunk and corrosion, followed by an abrasive media blasting, many previously hidden flaws will be readily visible. Look for cracks alongside bolt holes and in the valley area and adjoining freeze plugs. Cleaning the block will reveal old repairs and hidden damage.
Shown here is a stripped-out head bolt hole. Although a serious problem, this can be readily repaired with a Heli-Coil.
Once cleaned up, many previously hidden flaws will be readily visible to the eye during a careful inspection. Look for cracks alongside bolt holes, in the valley area, and at adjoining freeze plugs. Block cracks can be further identified and evaluated with a magnetic tester, but you need to suspect where they are before you can really test them. Cast-iron cracks can often be repaired by either welding or pinning. Both of these are challenging repairs best put into the hands of folks with a fair amount of experience. It’s not a really good place to practice a new skill unless you are willing to sacrifice a block to the learning curve.
Stripped or damaged bolt holes are common in old castings and are readily fixed with a thread insert. The most popular of the repair inserts is a Heli-Coil, where the hole is drilled and tapped to an oversize and a stainless-steel wire spring is wound into the hole. The result is a perfectly good thread with no real downside. This work is well within the skill level of most any home engine builder, and with a little care can be easily done successfully. Making a simple drill jig will help you keep the holes straight and perpendicular to the part.
Professional Mechanic Tip
One unique area to check on an FE engine is the oil feed passage that runs from the cam bearing up to the deck on each side. This hole feeds oil to the rocker arm assembly and has been known to crack on occasion, allowing oil to get into the coolant.
One unique area to check on an FE engine is the oil feed passage that runs from the cam bearing up to the deck on each side. This hole feeds oil to the rocker arm assembly, and has been known to crack on occasion, allowing oil to get into the coolant. You can pressure check this by covering the hole at the cam bearing end with your finger and putting just a bit of air into the top of the passage using a rubber tip air gun. It should appear airtight; if you hear air blowing into the cooling jackets you have a leak. The fix is to install a sleeve (a piece of tubing) into the passage. While we make a sleeve in our shop, I have heard of folks using brake line tubing or old pushrods for the purpose. The sleeve needs to fit snug but not necessarily super tight, and be lightly tapped/pressed into place. We usually lightly coat the outside of the sleeve with silicone before installing it for added insurance.
Our next step in preparation is to do a sonic test. This is also recommended when you bore a block out beyond .030 or .040 over because FE engines are noted for having fairly thin cylinder walls. It’s far better to know beforehand whether you should start off with a different block than to discover a thin wall or core shift after investing in the machine work.
Critical Inspection
Regardless of the type of build, it always provides peace of mind to do a sonic test, which is a test for the thickness of your cylinder walls. It is an optional process for most rebuilds, but a nice thing to consider for anybody working on a rare or expensive block. This is also recommended when you are boring a block out beyond .030 or .040 over, as FE engines are noted for having fairly thin cylinder walls.
Sonic testing is used to determine metal thicknesses in places that are not easily measured. To perform a sonic test you must first calibrate the tester to your block. The front face provides a spot that can be easily measured and the tester can be set up to match the actual measurement.
