Ford 347 Engine Build - Garage-Built Stroker

We checked the top and bottom of the bore to determine the taper. We heard the maximum should be no more than 0.003 to 0.004. We think if it is more than 0.003, you should take the block to the machine shop for boring and honing.

The next step is to completely scrub the engine with warm water and a mild detergent like Tide. We also ran a set of engine brushes through the oil galleries and lifter bores. We removed the oil gallery plugs and left the freeze plugs in place. After the cleaning, we blew out the passages with compressed air and added a light coat of oil to any unpainted surface.

We also removed the new Eagle stroker crankshaft from the box and cleaned it thoroughly with carb cleaner, then toweled it off with a terry cloth that doesn't shed fibers.

With everything clean and dry, we grabbed a set of standard bearings, added some assembly lube, and installed them in the block and main caps.

The main caps are marked for location with the arrows pointing toward the timing chain and marked in sequence. Since we are going to check the rod to block clearance, we did not torque the main caps at this time.

The forged pistons in the Eagle stroker kit have full-floating wristpins. That means we didn't have to take them to the machine shop and have the pins pressed in, saving time and money.

The pins are held in with a wire lock. We were careful to make sure the lock was seated by inserting one end of the lock into the groove and spiraling the lock into place. Do not squeeze the lock to install it; it will permanently deform. We prefer to build piston/rod combinations as pairs. The beveled edge of each rod faces the crank cheek, and the flat sides of the rods face each other on each rod journal.

To test-fit for block clearance, we installed the pistons without the rings. To keep the rod from swinging and damaging the cylinder walls, we rotated the engine so the cylinder was dead vertical, rotated the crank so the rod journal was at the bottom of its stroke, and tapped in the assembly with the handle of a rubber hammer.

Once each rod was installed with the rod cap, we marked the bottom of the cylinders for the rod bolt clearance and removed the piston assembly. For the clearancing, we used a Makita electric die grinder and a carbide bit. It only takes a touch to remove enough metal, so we worked slowly.

The stroker kit has pregapped rings for this particular bore, but that doesn't mean we didn't check them with a feeler gauge. For an N/A engine, the top ring gap is 0.0045 per inch of bore diameter. For a mild nitrous engine, the gap should be 0.005 per inch on the top and intermediate compression rings. We measured the gap with the ring squared 1 inch down the bore. If the gaps are tight, Childs and Albert sells a ring machine to file-fit the rings.

As you increase the stroke on an engine, you also shorten the compression height of the piston, and in this case, the piston pin intersects the oil ring. Federal-Mogul supplies a steel spring groove spacer that takes the place of the lower oil ring support rail to add extra support to the oil control ring. The spacer should be installed on the bottom of the third piston groove with the gap 90 degrees from the pinhole. The gap is 0.010.

We installed the oil expander with the gap butted over the wristpin, but we've also seen the gap butted over the piston skirt 90 degrees away. The point is to make sure the expander does not overlap. The upper and lower oil support rails should be at the 7 and 11 o'clock positions when looking down on the piston from the back of the block or along the piston pin centerline.