Ford FE Engines. Barry Rabotnick

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.

Sonic Checking Charts

      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.