The various parts and components of your engine have now been cleaned, inspected, and measured where necessary to determine if they remain within factory tolerances or will require machine work to return them to specification. This is the time to assess where your project stands and in what direction you wish to proceed. Is your budget such that the most economical approach is your only option? Or, is this to be a “money is no object, give me nothing but the best” rebuild?
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Most projects fall somewhere between a quick clean-up hone of the cylinders plus having the piston skirts knurled to get a few more miles out of them and ordering up an all-outracing buildup. A word of caution here: sometimes the most expensive and exotic approach is not always the best. Instead, I recommend selecting quality parts that compliment one another and your engine (referred to in racing circles as “your combination”) based on the advice of a competent machinist and engine builder.
Some decisions, however, will have already been made for you, particularly in the area of the cylinder block, crankshaft, pistons, and heads. For instance, if your cylinder bores are no longer within tolerance, you will be faced with boring the block, which will in turn require you to purchase oversized (larger-diameter) pistons. During your engine rebuild you will more often than not have the choice to either reuse, refurbish, or replace parts. In the following chapters, you’ll see where I chose to replace original equipment parts with those that feature advances in design and material to gain the best possible results.
Replacement and Performance Parts
Cylinder wall wear and rust necessitate that our block be bored .030 oversize to 4.390 inches. This has allowed us to use pistons that are superior to the OE parts in design and material and will also allow us to reduce the compression ratio slightly to achieve a combination that is more compatible with today’s loweroctane fuel. The Keith Black hypereutectic pistons are lighter weight and feature a slight dish in the top, as opposed to the OE piston, which has flat top with one valve relief.
The Keith Black pistons we have selected for this rebuild feature an accumulator groove between the first and second ring. The purpose for this groove is to trap blow-by (gasses escaping past the top piston ring), thus providing a better seal and a cleaner, more efficient engine.
We’ve also chosen a Competition Cams Extreme Energy camshaft and kit with a mild grind: advertised .487-inch intake and .493-inch exhaust lift, with 256 and 268 degrees of intake and exhaust duration, respectively. This cam will provide a smooth idle and good low-to-midrange torque. The kit also contains matched valvesprings, hydraulic lifters, and assembly lube. We will also be using valve keepers supplied by Crane Cams in order to compensate for the stem length differences between the OE and aftermarket exhaust valves we’re using.
In an effort to retain original date coded and correct casting number parts on our rebuild, we chose to have the original water pump rebuilt by A-1 Cardone. If originality is not your top concern, rebuilt water pumps are readily available for Lima series engines through most auto parts stores.
For those seeking maximum engine performance, a number of different suppliers, including Ford Racing Parts, offer Lima series cylinder heads in cast aluminum. While somewhat expensive, these heads provide incredible horsepower increases via greatly improved flow through redesigned intake and exhaust ports and combustion chambers. They also reduce the overall engine weight.
The Lima series short block in this photo makes use of custom pistons and an aftermarket crankshaft with a longer-than-stock stroke, which has increased its displacement from 460 to 514 ci. These modifications will greatly increase this engine’s horsepower and torque output.
Aftermarket H-Beam connecting rods are a typical choice for extreme performance applications. Not only are they stronger than OE connecting rods, they are lighter as well. By reducing the weight of the reciprocating assembly, the engine will rev faster and produce more horsepower. The threaded studs protruding from the main bearing caps allow you to mount a windage tray, which provides additional horsepower by separating the crankshaft from the oil in the pan, thus reducing the frictional drag created when the crankshaft comes into contact with the oil.
One replacement part I consider a must for any Ford engine rebuild is a heavy-duty oil pump driveshaft. Many Ford engines have a reputation for oil pump driveshaft failure under extreme conditions. Compared to the OE shaft on the left, the heavy-duty drive supplied by ARP is far stronger to resist flexing and possible failure. The clip seen at the top prevents the drive from being pulled out of the oil pump if the distributor is removed and should always be in place.
Written by Charles R. Morris and Republished with Permission of CarTech Inc
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