Build Some American Motors Horsepower with Engine Power AMC 304 Parts Combos

When Tommy Boshers from PowerNation TV’s Detroit Muscle wanted to get some more oomph out of the 304 cubic inch V8 in his 1973 AMC Javelin project, he naturally turned to Pat Topolinski and Frankie Forman next door at Engine Power. The goal was not the usual fire-breathing, high-strung beast of a powerplant. Rather, Tommy was looking for something that made good streetable power with manners any mother would be proud of.

Pat and Frankie delivered. The little 304 is a junior powerhouse that made 337 peak horsepower at 5,000 RPM and 333 lbs.-ft. peak torque at 4,700 RPM—not too shabby for an engine with an 8.3:1 compression ratio.

You can see how the Engine Power wizards did it at PowerNationTV.com, and check out the parts they used in our Engine Power AMC 304 Engine Build Parts Combos.

Short Block
With the Javelin strapped to the chassis dyno, the 304 sent a whopping 130 horsepower to the rear wheels. When Pat and Frankie cracked the engine over, everything was covered in gunky, oily residue—a sign of a neglected engine. The main and bearings were shot too, with lots of copper showing. It was so bad, Pat gave the engine the Nastiest Engine award.

On the plus side, there was no oil in the combustion chambers, and the cylinder bores still had some cross hatch pattern left. Even though the bearings were in bad condition, the crank journals were round and in decent shape. A polish job restored the crank to like new.

The block was cleaned up and bored .060 inch over to restore the cylinder walls and remove the ridges at the top of the bores. A set of Sealed Power OEM replacement cast pistons with Total Seal rings were clipped to resized factory connected rods outfitted with ARP bolts. The cam, rod, and main bearings were replaced with new Clevite bearings.

To help the 304 make some power, Pat and Frankie installed a COMP Cams hydraulic roller cam rated at 224°/230° duration @.050, and .513" lift. They advanced the cam four degrees to a 106 degree intake centerline.

AMC V8s have an oil pump that is built into the timing cover. Instead of replacing the pump, you have to rebuild it. Melling makes a rebuild kit that makes the job a cinch.

Rounding out the parts combo is a Milodon stock replacement oil pan, Fel-Pro gaskets, a COMP Cams Magnum double roller timing set, and a Professional Products PowerForce harmonic balancer.

Cylinder Heads, Valvetrain, and EFI
The 304’s factory cylinder heads are actually pretty good. They have dogleg-style exhaust ports that flowed extremely well, to the point that the ‘Gen-3’ AMC heads of the early 1970s outflowed performance-prepped Chevy, Ford, and Mopar heads of the day.

However, the factory heads’ 1.787 inch intake and 1.406 inch exhaust valves were too small to take advantage of the new COMP camshaft. Since AMC 304, 360, and 401 engines share a block, the cylinder heads are physically interchangeable. A popular upgrade for the 304 is to use cylinder heads designed for a 360 or 401, which have bigger ports and flow more air.

Pat and Frankie chose a set of Edelbrock Performer RPM aluminum heads. The Performer RPMs have bigger 185cc CNC-machined intake runners and 54cc combustion chambers with 2.02/1.600 inch valves. The heads are designed for the 4.080 inch and larger cylinder bores, so Pat had to notch the 304’s smaller 3.810 inch holes for intake valve clearance. The heads were fastened to the engine with ARP cylinder head bolts.

The valve springs were shimmed .090 inch to provide enough spring pressure for the roller cam. Our combo includes Dart .030 inch thick shims to do the job. A set of 1.6 ratio Harland Sharp roller rocker arms were installed to reduce valvetrain friction. Rounding out the valvetrain are COMP Cams High Energy roller lifters and Hi-Tech pushrods.

Filling the gap between the cylinder heads is an Edelbrock Pro-Flo 4 port EFI system. The sequential multiport system can support up to 550 horsepower. You can let the Pro-Flo 4 self-learn your engine as you drive, or you can dive in and tune it yourself with the E-Tuner 4 software loaded on the handheld tablet.

Completer Parts
Pat and Frankie used the electronic distributor from the Edelbrock Pro-Flo 4 EFI kit, an MSD Blaster 2 coil and Super Conductor wires, and a set of NGK V-Power spark plugs to deliver spark to the 304’s combustion chambers. A set of Patriot Performance Clippster headers with 1 5/8 inch primaries are also included in the combo.

CHECK OUT THE ENGINE POWER AMC 304 PARTS LIST