view of the bottom end of a ford 390 block with crankshaft removed
opening a box of engine gaskets
putting rtv on a rear main seal prior to install
staggered rear main seal prior to main cap install
sliding in the rear main seal into a main cap
putting rtv on a ford fe series rear main cap
applying sealant to the rear main seal cap on a ford fe series engine
installing the rear main cap on a ford fe series engine
hammering a drift into a ford 390 fe series engine
lubricating engine bolts with engine oil
checking for crankshaft endplay on an engine
installing forged pistons into a ford engine
tightening connecting rod bolts on a ford engine
checking for top dead center on a ford engine
lubing distributor gear teeth on a ford camshaft
degreeing a camshaft on a ford engine
Milling a ford engine cylinder head
installing hardened valve seats in a ford cylinder head
engine intake and exhaust valves in a ford 390 cylinder head
close up of ford 390 main bearing galley
deburred edge on a ford 390 engine casting
water pump on the front of a ford fe series engine 390
rocker arms lined up on a workbench
rocker arms inside a cylinder head
timing pointer on a ford fe series engine
carter fuel pump on a ford fe series engine
arp fasteners installed in a ford 390 fe series engine
pouring break in oil into an engine prior to firing
prelubing a ford 390 fe series engine with a drill
pertronix flame thrower distributor on a workbench
installing a distributor onto a ford 390 FE series engine
holley hp 750 carburetor on an engine
using a gapping tool to gap a spark plug
man fitting headers onto a ford fe series 390 engine block
390 ford fe series engine on a dyno test run

Ford’s 390 FE series block offers a rugged demeanor in its skirted block and thick main webs. There’s plenty of room for increased stroke along with a .030-, .040- or .060-inch overbore to achieve 430+ ci. JGM Performance Engineering has prepared this block for greatness cutting the decks, massaging the line bore, and boring/honing cylinder bores .030-inch oversize to 4.080-inches. Speed Pro standard size main bearings have been set in the block and we’re ready for assembly.

JGM has opted for a Fel Pro #FEL-KS2307 gasket set from Summit Racing. The Fel Pro kit has every gasket you’re going to need to assemble your Ford 390. Don’t forget a tube of Permatex’s The Right Stuff to compliment your Fel Pro gaskets as needed.

The 390’s rear main cap seals can be problematic but not if you install them properly. Crankshaft seals should get a thin layer of The Right Stuff between the seal and block, and then the seal and cap. Seal grooves must be hospital clean.

Stagger crank seal ends away from main cap to block mating surfaces. Seal tips should get a dab of The Right Stuff. Before you set the crank, lube seal lips with engine assembly lube and make sure seal lips are pointed toward the crank, not away

Side seal groove get The Right Stuff first, then, set each side seal.

Rear main cap is carefully set with a modest application of The Right Stuff between cap and block. Reinforcement pins are driven into the side grooves with caution while sealer is still moist. Once The Right Stuff sets it will not leak.

All fasteners should be lubricated with SAE 30 engine oil or ARP fastener lube to ensure proper torque. Although we have gone with original main cap bolts here, it is suggested you opt for ARP #ARP-155-5401 main studs for bottom end security. Never bottom out main studs. Leave 1/8 to 3/16-inch of space between stud and bottom.

Crankshaft endplay should be checked during mock-up, not final assembly. Endplay should be .004- to .010-inch.

Mahle coated forged pistons are an integral part of our Eagle #ESP-158124080 stroker kit and are nice pieces. Eagle has designed in a 7.000cc dish to compensate for increased stroke and corresponding compression. Forged steel 5140 I-beam rods and a cast steel crank will easily accept 500 horsepower. Bore is 4.080-inches with a 4.125-inch stroke compared with the 390’s stock stroke of 3.780-inches.

True top dead center is checked using a dial indicator prior to degreeing the Crane hydraulic roller cam.

JGM Performance Engineering opted for a Comp Cams hydraulic roller, #33-422-9, which delivered unexpected power bonuses on the dyno. Lobe centers are 110 degrees with .301-inch lobe lift and a whopping .529-inch at the valves. Duration at .006-inch is 270 intake and 276 exhaust. Moly lube is applied to the distributor gear, which must be steel or bronze with a roller cam. Comp Cams also has a cool composite distributor gear available from Summit. Engine assembly lube is applied to lobes and journals.

Although a lot of us elect to install a camshaft and with blind faith not degree the cam. However, you must always degree the cam to ascertain cam specifications and be sure you’re getting what you ordered. Play it safe and always check.

JGM’s customer brought in a pair of 1968 390 GT cylinder heads and a 428 Police Interceptor intake manifold in the interest of authenticity in a mild Mustang GT restomod. Results on the dyno were stunning — and without port work. The C8AE GT Thermactor head, which isn’t even the best FE head, sports a 67-70cc chamber with 2.020-inch intake and 1.550-inch exhaust valves. We’re milling these heads for trueness and a slight boost in compression. (Image/Jim Smart)

Hardened exhaust valve seats are being installed for durability with today’s fuels along with a three-angle valve job. It is always a compromise. If you keep valve seat width narrow you get flow, yet lose valve cooling. If you go wide, you lose flow and improve valve cooling. These are Speed Pro stainless steel valves from Summit.

Two things are evident here. JGM has modified main bearing galleys for improved flow. This block has also been line honed to a nice crosshatch for good bearing security.

Block and head deburring helps eliminate the risk of cracking.

Summit Racing Equipment offers you original equipment replacement high volume cast iron water pumps as well as aftermarket pumps from Edelbrock and Weiand. You’re also going to need a 180 degree thermostat, cooling system hoses, and clamps. Evans coolant is your best bet because it never has to be replaced.

JGM has chosen to go with Crane 1.76:1 shaft-mounted roller rockers from Summit per the customer’s request. Here, we’re doing a mock-up to determine proper valvetrain geometry via correct pushrod length. These are really nice adjustable rockers that have proven a good fit with an easy to service demeanor.

JGM ordered the Dorman #RNB-594-146 stock replacement harmonic dampener for this 390 FE project, which is an excellent budget street balancer.

This is a Carter stock replacement fuel pump for the 390. Summit offers a variety of high-performance fuel pumps from Holley and Carter for your FE performance project.

JGM has opted for ARP fasteners from Summit throughout this engine for reasons of integrity. This is suggested for any engine project in the interest of durability due to bolt stretch and a stress issues.

We’re running Comp Cams Muscle Car & Street Rod 10W30 weight engine oil for our break-in on the JGM dyno. Once the Canton road race pan is filled, Jeff Latimer of JGM primes the 390’s oiling system for a good wet start.

Pertonix’s new Flamethrower ignition system with the Ignitor III module inside punctuates Pertronix’s reputation for incredible ignition systems. This is the Pertronix #PNX-D7133700 distributor, which is being tuned on the engine before fire up.

Here’s the Holley HP 750cfm carburetor, #HLY-0-82751, which helped us cash in on real power across rpm ranges. We could have gone with an 850cfm atomizer for this effort yet chose 750 for a broader power band yielding good low-end torque.

On Summit’s shelf were Autolite spark plugs gapped at .035-inch per the Ford Shop Manual. You can actually go wider at .040-inch with a high energy ignition.

Ford Powertrain Applications makes a nice perfect fit header for the 390 designed specifically for Mustang, Fairlane, Torino, and Cyclone. These are ceramic coated for longevity and good looks.

JGM Performance Engineering wound up with a nice street 390 FE built for traffic light to traffic light and weekend strip performance providing a broad torque curve that comes on strong at 2,000 rpm and pulls all the way to 6,000.

Ford’s timeless FE series big-block has been making legendary amounts of power for nearly 60 years with those first examples showing up for ’58 in Ford, Mercury, and Edsel. Early on, displacement wasn’t much to write home about with its 332-, 352 and 361-cubic-inch options. However, Ford engineers and product planners quickly went to work infusing more displacement into this history-making big-block series, ramping up displacement to 390, 406, 410, 427, and 428 cubic inches. There was also the 360 FE for trucks.

Of all the FE series big-blocks produced during the type’s 18-year production run, the 390 is easily the most common. With a 4.050-inch bore and 3.780-inch stroke there’s plenty of room to grow this engine into a 430-plus cubic inch beast without spending a lot of money. And once you have the increased stroke from Eagle Specialties and resulting displacement from a cast steel crank and I-beam rods, Summit can help get you into real power with Edelbrock Performer series cylinder heads and induction, a COMP Cams roller hydraulic camshaft and Crane Cams roller rockers, Pertronix or MSD ignition, Holley carburetion, and more. You can scarf it all up in one stop and wait for UPS to knock on your door with the goods.

We stopped by JGM Performance Engineering in Valencia, CA, which was building a 390 FE stroker for a Pennsylvania customer with a Mustang. We were astonished by the power JGM was able to get from a modest increase in stroke using cast iron 390 GT heads and 428 Police Interceptor induction topped by a Holley HP. JGM was able to get 450-plus horsepower and roughly 400 ft.-lbs. of torque using Ford heads and induction, a hot Crane roller hydraulic cam, and a very detailed approach to tuning on the dyno.

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Author: Jim Smart

Jim Smart is a veteran automotive journalist, technical editor, and historian with hundreds of how-to and feature articles to his credit. Jim's also an enthusiast, and has owned and restored many classic vehicles, including an impressive mix of vintage Ford Mustangs.