Measuring the block’s critical dimensions will determine if it remains within the tolerances recommended by the manufacturer. If the cylinder bores remain concentric and show no excessive taper, you may be able to get away with just honing them. But keep in mind that during the honing process, material is being removed from the cylinder walls, which may take the bore beyond tolerance. In other words, if in doubt, opt to bore the cylinders. Any high-mileage engine will greatly benefit from boring, as the process will restore the cylinders to a concentric shape and improve their alignment relative to one another.
This Tech Tip is From the Full Book, HOW TO REBUILD BIG-BLOCK FORD ENGINES. For a comprehensive guide on this entire subject you can visit this link:
SHARE THIS ARTICLE: Please feel free to share this post on Facebook / Twitter / Google+ or any automotive Forums or blogs you read. You can use the social sharing buttons to the left, or copy and paste the website link: https://www.diyford.com/machine-cylinder-block-big-block-ford-engine-rebuild/
Once you’ve decided to bore the block, you must decide by how much. As a general rule, you want to bore the cylinders as little oversize as possible. For most engines, it is easy to obtain pistons and piston rings between .020 and .060 inch oversize. But in the case of Lima and some other series Ford engines, your options may be more limited. Machine shops will often recommend boring your cylinders to the next oversize that is closest to, say, a Chevrolet bore size, thus increasing the availability and reducing the price of piston rings. Pistons are another matter altogether, as there are a number of factors aside from oversize to be considered. I’ll discuss that in more detail a little further along in this chapter.
Cylinder Block Step by Step
Step-1: Set Up Cylinder Block in Boring Machine Work
After being measured, cleaned, and Magnafluxed, the block is set up in the boring machine. We decided to bore our block .030 inch oversize due to wear from high mileage and rust in the cylinders due to the engine having not been run for a number of years.
Step-2: Bore the Cylinders
The boring bar works to remove taper and makes each cylinder concentric again in preparation for finish honing. The actual boring process removes approximately two to three thousandths less material from the cylinder than the total planned oversize, allowing the honing process to finish the cylinder to the proper size for the piston.
Step-3: Hone the Cylinders
After boring, the block is set up in the cylinder hone for finishing. The machine uses stones with two different grits, while cutting oil is introduced to achieve the proper finish in each cylinder bore.
Step-4: Use High Plateau Hone (if applicable)
We’re using a High Plateau hone to aid in sealing with Moly piston rings. Gil Jordan recommends 15 to 20 strokes in each bore with the hone affixed to a 1/2-inch drill motor.
Step-5: Use Cross-Hatch Pattern
The desired finish for the cylinder walls is this fine cross hatch of approximately 30 degrees. This allows the piston rings to seat and seal quickly and thoroughly.
Step-6: Clean Up Lifter Bores
Use a ball hone to clean up the lifter bores. While lifter bores seldom display problems, they can be damaged due to lifter failure during high-performance operations or pitted due to rust. In these cases, lifter bores can be sleeved and honed back to factory specification to save an otherwise good cylinder block. Larger diameter ball hones are sometimes used to clean up cylinder bores that are not undergoing a complete machining process.
Step-7: Replace Cam Bearings
The cam bearings must be replaced any time a block has been chemically degreased. We have chosen these Dura-Bond high-performance bearings for the job.
Step-8: Install Cam Bearings
A specialized tool and some experience are required to install the cam bearings in the block. While Lima series Ford engines use just one size of cam bearing in each journal, others have specific bearings for certain journals (getting smaller moving back from the front journal where the loads are greatest). Using a single size for all cam bearings is considered one of the few weaknesses in the Lima series engines, as they sometimes have a propensity to spin cam bearings due to insufficient lubrication or clearance. As a result it is important to ascertain that the oil feed holes between the cam bearings and the cylinder block are properly aligned and that the camshaft spins freely when installed. Manufacturers have a recommended setback (from the face of the block) measurement for the number-1 (front) cam bearing. The most important thing is proper alignment between the bearing and the oil passages that feed them from galleries in the block.
Professional Mechanic Tip
A Lima series block that has suffered a spun cam bearing(s) is not necessarily doomed to the scrap heap. Your machine shop can save the block by line boring the bearing bores and using cam bearings for an FE series Ford engine, which have the same 2.124-inch ID cam journals as the Lima series but are progressively larger in outside diameter moving front to back in the block.
Step-9: Modify Oiling System – optional (Performance Tip)
There are a few simple oiling system modifications that will greatly aid oil flow and ensure the longevity of your engine. The oil passage that is located at the point where the oil filter is mounted to the block is enlarged, blended, and chamfered with a high-speed grinder to assist the flow of oil.
Step-10: Chamfer Oil Passage (optional)
Using the gasket that fits between the oil pump and cylinder block as a template, match and chamfer to this passage using a high-speed grinder.
Step-11: Match Oil Passage to Bearing
Placing the top half of a main bearing insert into its saddle in the block will usually reveal a serious mismatch between the oil passage in the main bearing web and the groove in the bearing, which carries the all-important cooling and lubricating fluid to the crank. A hand grinder will easily correct this situation by matching the oil passage to the bearing. On Lima series engines, this mismatch is most often encountered in the front (number-1) main.
Step-12: Passages Chamfered
The oil passages in this crankshaft rod journal have been chamfered and smoothed, which will ensure an adequate flow of life-giving oil to the bearing. Only a thin coat of oil lubricates and cools the friction surfaces between the bearings and the rotating assembly, and a proper supply is paramount to engine longevity.
Crankshaft, Pistons and Connecting Rods Step by Step
Step-1: Connecting Rods
Lima series Ford engines came out of the factory with some pretty beefy connecting rods, so chances are, unless your engine has suffered some catastrophic failure, you’ll be able to reuse the stock rods. Even in cases where an engine hasn’t been abused, you must take into consideration the wear and tear and the pressures exerted on the connecting rods. They must be checked to ensure that the big ends (crankshaft journal end) remain concentric. This is accomplished on the Sunnen connecting rod machine. The cap is placed back on the rod and tightened to the correct torque specification before the machine measures the diameter.
Step-2: Fit Rod Bolts
Prior to resizing, we’ve fit our connecting rods with ARP rod bolts. I have found that installing new original equipment or quality aftermarket rod bolts is an inexpensive way to avoid premature failure of a rebuilt engine. Special Note: ARP recommends specific procedures to be followed when using their connecting rod bolts, one of which describes the use of a stretch gauge for obtaining proper torque. If you do not have a stretch gauge, they recommend using ARP Moly Assembly Lube on the bolts and perform three torque cycles of 50 ft-lbs on the bolts to achieve proper stretch. Also note that ARP rod bolts use different torque specifications than OE bolts.
Written by Charles R. Morris and Republished with Permission of CarTech Inc
GET A DEAL ON THIS BOOK!
If you liked this article you will LOVE the full book. Click the button below and we will send you an exclusive deal on this book.