Ford 347 Engine Build - Budget Small-Block Ford Stroker Assembly

Here is why this is good: We ordered this Eagle 347 Ford rotator kit online from Summit Racing and had it delivered to our front door for less than $1,000. For the money, you get a crank with an additional 0.400-inch stroke, hypereutectic pistons, and forged-steel I-beam rods. All the math and machine work is done, and the assembly is already balanced with a damper and a flexplate. The rods and bearings have been chamfered for the crank fillet, the rings are pregapped, and everything is matched so there is no interference between parts.

The most amazing aspect of the rotator is it can be installed while in your garage, provided your engine doesn't have massive taper in the cylinder bores, the main bearing bores are aligned and round, and the deck is flat. It means a good-running, low-mile 302 or recent rebuild is the best candidate for this swap. You should be able to add 45 inches of displacement in one weekend. You just have to be OK with the use of a die grinder, bore gauges, and micrometers.

Another cool thing about this build is we ordered the entire parts list online from Summit Racing without leaving the house. That includes the drip pan, tools, and stroker kit. No more parts runs.

Another cool thing about this build is we ordered the entire parts list online from Summit

The engine we are using for this job is the 302 we originally pulled out of a '73 Ranchero and was refreshed in the Nov. '07 issue ("Build the Cheapest Engine Possible") by JMS Racing Engines in El Monte, California. With stock heads, it made 279 hp and 341 lb-ft. Then we added a set of AFR 165cc Outlaw Street heads and picked up 92 hp and 37 lb-ft. For the final story, we added a set of pop-up JE pistons, revved the engine to 7,500 rpm, and made 479 hp and 387 lb-ft while simultaneously reaching what is likely the maximum output of an N/A 302.

We asked around about the difference between a 347 and the 331 stroker kit for the 302. We heard the 331 needs to rev beyond 6,500 rpm to make the same power as the 347, making the larger engine slightly more reliable and streetable. The 347 will also make more usable torque. Machinists we talked to also claim the angularity of the rod is greater with the 347, which is true. It may cause increased wear on the cylinder wall on a high-mileage engine-that is also true. On the 347, you are pulling the piston down to the bottom of the bore, increasing the likelihood that the piston will rock, as the skirts are uncovered at the bottom of the stroke. The most practical complaints are that the longer stroke requires block clearancing, the counterweight can hit the oil pump, and the rod is long enough that the piston pin intersects with the oil ring bore, possibly causing oil control issues.

Eagle fixed these problems with heavy-duty oil support rails and a tapered piston to reduce noise. Our advice is to measure everything before you order and build the thing.

The first step after removing the tin is to pull the balancer. This puller is also an installer and fits a variety of engines.
The first step after removing the tin is to pull the balancer. This puller is also an inst
We are going to save the stock rotator, so after we pulled the rod bearing cap, we added rod bolt protectors to keep the threaded end from scratching the crank. To remove the piston from the bore, use a knocker or a rubber or wooden hammer.
We are going to save the stock rotator, so after we pulled the rod bearing cap, we added r
The first precision tool we used was a dial bore gauge. Note the anvils in the foreground. They are used along with a micrometer to preset the exact dimension to be measured. In this case, we used the 4.00-inch anvil and the 0.100 washer and set the dial indicator to zero. A 4.100 bore gauge in a 4.030 bore should swing the gauge 0.070. Get it?
The first precision tool we used was a dial bore gauge. Note the anvils in the foreground.

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.
We checked the top and bottom of the bore to determine the taper. We heard the maximum sho
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.
The next step is to completely scrub the engine with warm water and a mild detergent like
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.
We also removed the new Eagle stroker crankshaft from the box and cleaned it thoroughly wi

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.
With everything clean and dry, we grabbed a set of standard bearings, added some assembly
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 main caps are marked for location with the arrows pointing toward the timing chain and
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 forged pistons in the Eagle stroker kit have full-floating wristpins. That means we di

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.
The pins are held in with a wire lock. We were careful to make sure the lock was seated by
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.
To test-fit for block clearance, we installed the pistons without the rings. To keep the r
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.
Once each rod was installed with the rod cap, we marked the bottom of the cylinders for th

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.
The stroker kit has pregapped rings for this particular bore, but that doesn't mean we did
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.
As you increase the stroke on an engine, you also shorten the compression height of the pi
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.
We installed the oil expander with the gap butted over the wristpin, but we've also seen t

We installed the second compression ring next using a ring expander and positioned the gap in the 9 o'clock position looking down on the engine from the rear. The top ring will be marked with a T, a dot, or even the word Top stamped into it. We placed that gap in the 3 o'clock position.
We installed the second compression ring next using a ring expander and positioned the gap
After ensuring the bore was in good condition, we used the dingle-ball hone to remove the glaze on the cylinder walls. Using a pumping motion, we spun the hone with a light honing oil until we had a crosshatch pattern in the bore. This helped seat the new rings.
After ensuring the bore was in good condition, we used the dingle-ball hone to remove the
After we clearanced and honed the block, we gave it another scrubbing with detergent and a lot of water to remove all the metal shavings from the bores and oil holes. Since we did not replace the cam bearings, we took extra care to make sure they were clean and dry.
After we clearanced and honed the block, we gave it another scrubbing with detergent and a

With the block cleaned, we started the final assembly by installing the main bearings to check for correct oil clearance. We asked around and found that many people reuse the main cap bolts, so we did, too. We cleaned them, lubed them with ARP moly-lube, and torque them to 70 ft-lb.
With the block cleaned, we started the final assembly by installing the main bearings to c
Using the micrometer, we preset the dial bore gauge to 2.250 and zeroed the dial indicator.
Using the micrometer, we preset the dial bore gauge to 2.250 and zeroed the dial indicator
With the gauge preset, we measured the torqued main cap's bore diameter by adding the difference between the preset measurement and the reading on the gauge. The bore was 2.2517.
With the gauge preset, we measured the torqued main cap's bore diameter by adding the diff

The main bearing journal on the crankshaft was 2.2490 inches, making the bearing clearance 0.0027. The official recommendation is 0.002 to 0.003, so we were just inside the spec.
The main bearing journal on the crankshaft was 2.2490 inches, making the bearing clearance
After checking all the main bearings, we made sure to clock the oil seal on the No. 5 main cap, installed the crank with a coat of assembly lube on each journal, and torqued the main caps.
After checking all the main bearings, we made sure to clock the oil seal on the No. 5 main
The final check is the thrust bearing clearance. Using a pry bar, we gently moved the crankshaft back and forth while watching the dial indicator. The allowance is 0.0040 to 0.0080. Ours showed 0.0062.
The final check is the thrust bearing clearance. Using a pry bar, we gently moved the cran

We checked the rod bearings in the same manner as the main bearings after tightening on the bearing caps with the rod in the soft jaws of the vice. The spec was 0.002 to 0.003.
We checked the rod bearings in the same manner as the main bearings after tightening on th
We don't listen to people who tell us to install the pistons in a dry cylinder to break them in. Add a film of oil to the cylinder and lightly coat the piston with engine oil to keep things sliding off each other. We used a ring compressor with the correct bore size.
We don't listen to people who tell us to install the pistons in a dry cylinder to break th
After reinstalling the piston and rod assembly, we checked the gap between the rods with a feeler gauge for between 0.015 and 0.025 of side clearance. For the final assembly, we used a stretch gauge instead of a torque spec. The spec for a 3/8-inch capscrew is 0.0060 to 0.0067 bolt stretch. The tool was installed with the point of the dial indicator on the dimple at the top of the capscrew and the set screw on the bottom. After preloading the dial indicator 0.200 to 0.400 and zeroing the gauge, we slowly tightened the capscrew until we saw 0.0060 on the dial indicator.
After reinstalling the piston and rod assembly, we checked the gap between the rods with a

JMS also recommended we add a windage tray or an aftermarket pan. The extra stroke tends to dip the counterweights into the oil, causing foaming and loss of horsepower. Because the deck height is 8.200 on our block, the pistons are at zero deck. With the 58cc chamber on the AFR heads, the engine has a 10.9:1 compression ratio. That will work with pump gas and we will add a little fog of nitrous for some street fun.

JMS also recommended we add a windage tray or an aftermarket pan. The extra stroke tends t

Engine Specs
Bore: 4.030
Deck: 8.200
Stroke: 3.400
Cubic inches: 347
Rod length: 5.400
Compression distance: 1.100
Valve relief: -5cc
Rod journal: 2.100
Main journal: 2.249

Engine Specifications
Torque Specs
Main cap: 65 ft-lb (with ARP moly-lube and bolts); 85 ft-lb (motor oil and stock bolts)
Rod cap: 50 ft-lb (3/8-inch ARP bolt and nut); 40 ft-lb (3/8-inch ARP capscrew); 20 ft-lb (stock); 0.0060 to 0.0067 bolt stretch

Tolerances
Main bearing clearance: 0.0025 to 0.0030
Rod bearing clearance: 0.0020 to 0.0030
Crank end play: 0.0040 to 0.0080
Rod side clearance: 0.010 to 0.020

Parts List
Description	PN	Price
Bolt protectors	CLE-2800B1	$2.39
SBF gasket set	FEL-KS2328	$59.25
Engine brush kit	MRG-5192	$26.75
4.030 ring compressor	SME-904030	$26.95
Outside micrometer	SUM-900014	$51.95
Rod bolt stretch gauge	SUM-900015	$64.95
Dial bore gauge	SUM-900041	$109.95
Engine stand drip tray	SUM-901011	$35.95
Balancer installer/remover	SUM-G1025	$94.95
Torque wrench (0-100)	SUM-G1055	$93.95
Engine assembly lube	SUM-LUBE	$1.95
Piston ring installer	WMR-W80575	$4.95
Eagle 347 FSB rotator	ESP-B16422LA030	$999.95

SOURCES
Summit Racing Equipment PO Box 909 Akron OH 44398 800-230-3030 330-630-0240 www.summitracing.com	Eagle Specialty Products 8530 Aaron Lane Southaven MS 38671 662-796-7373 www.eaglerod.com
JMS Racing Engines El Monte CA 626-579-4567 www.jmsracing.com