Jim Smart
June 1, 2000

Step By Step

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In standard form, the 347 Street Fighter consists of a nodular-iron crankshaft (3.400-inch stroke), Blue Thunder 5.400-inch-long connecting rods, Probe 4.030-inch hypereutectic pistons, Clevite bearings, plasma-moly piston rings and a high-volume oil pump. Coast gets the stroke by offset-grinding the crankshaft 0.060 inch. The block is bored 0.030 inch oversize. Most builds include a new block.
Coast pumps displacement up to 347 ci by including a unique custom piston that makes the 347 Street Fighter a more reliable engine than other available 347ci strokers.
This design keeps the oil ring out of the wristpin hole (arrow), which eliminates oil-control problems. H-beam connecting rods are nice options if you intend to go racing or ring it tight on the street.
Even if you’re stroking an older 289 or 302, we suggest stepping up to a roller tappet camshaft in your 347. A more aggressive cam profile helps your engine digest more air and more fuel, which improves torque.
Coast High Performance uses high-volume oil pumps in all its Street Fighter engines. Volume—not always higher pressure—keeps things lubricated under demanding conditions. Remember that the rule of thumb with oil pressure is 10 psi for every 1,000 rpm. If you expect to tach your 347 to 6,000 rpm, then you’re going to need at least 60 psi of oil pressure at that speed.
The optional main-cap girdle stiffens the block for high rpm use. Think of the stud girdle as you would the 427ci cross-bolt design: It stiffens the main caps.
Our subject block was an ’84-’85 5.0L roller block that hadn’t been drilled and tapped for the roller lifter spider. It had to be drilled and tapped for spider bolts. Block cleanup is mandatory after this step.
What makes a Coast High Performance engine an extraordinary value is attention to detail. These aren’t mass-produced crate engines—they’re custom-built one at a time. All machined surfaces are checked and rechecked prior to assembly.
If you have the option, we suggest you step up to a late-model 5.0L block that incorporates the 360-degree oil seal. This is as leakproof as it gets and beats the older half-seals found in the 289 and 302.
Coast uses Clevite bearings, which are able to withstand a lot of punishment.
We’re using a mid-’80s 5.0L block for our 347 build. Everything has been machined, and the block is ready for checking and buildup.
The main caps have been torqued to specifications, which allows engine builder Mark Jeffrey to check each main bearing.
Coast engines receive an abundance of assembly lube for a slippery start-up. No one wants the experience of dry bearings during a start-up. Jeffrey suggests priming the oiling system before the first fire-up.
The rear main seal saddle receives a mild dressing of sealer before the crank is installed. This makes for a foolproof, leakproof seal.
This is the custom-made, specially ground, cast-iron crankshaft that’s 347-specific.
Rods are torqued to specs and checked with a micrometer as shown. Close attention to detail is critical here.
The 347 Street Fighter has free-floating piston pins, which eliminate any binding and improve flexibility.
Plasma-moly piston rings provide a better seal and exhibit better wear qualities.
Coast uses this custom-sized piston ring compressor. It’s a taper-fit design that enables you to insert the piston into the bore without effort.
Coast High Performance double- and triple-checks torque readings on all its engine builds. Repeated checking means never having to say you’re sorry later.
Rod- and crank-side clearances are checked and rechecked.
Jeffrey uses this slick cam installation tool to fit the roller cam. The tool screws into the cam for ease of installation, which enables Jeffrey to be gentle on the cam bearings and journals.
Coast High Performance uses screw-in oil gallery plugs instead of original equipment press-in plugs.
The cam plate and timing set are installed next.
Don’t forget to specify the fuel pump eccentric if your 347 is for a pre–fuel-injected Mustang.
Coast uses new timing covers on its 347 Street Fighter. Be sure to specify your Mustang’s model year when ordering.
Next, the end gaskets are installed. For added protection against leaks, it’s a good idea to use sealer where the rail gaskets meet the end gaskets.
In this application, Coast is fitting the 347 with Edelbrock Performer heads. They flow better than a 351W head and weigh less. If you’re on a budget or desire a factory original appearance, then 351W heads are an affordable alternative. When using aftermarket heads, ascertain valve and chamber size before buying.
Roller tappets are installed next, along with the guides and the spider.
The spider holds the guides in place. Soak the lifters in 30W engine oil before installation.
Our completed 347 Street Fighter is prime for early- or late-model Mustangs. Coast High Performance can outfit your 347 for any application.

What do you want to do with your 302? Coast High Performance brings you the 347ci Street Fighter small-block for classic and late-model Mustangs. It screams with fuel injection and sizzles nicely with a carburetor. So check your excuses at the door. It’s time to increase displacement for about the same money it costs to do a standard rebuild on an engine.

The 347 Street Fighter employs an offset-ground iron or steel crankshaft, brute-strength Blue Thunder connecting rods, Probe custom pistons, and a host of options designed to make the most of your build. If you want H-beam Probe connecting rods that can withstand a 7,000-8,000-rpm spin, then Coast can accommodate you. Billet crank? No sweat. Trick Flow or Edelbrock heads? Sure. For those of you in the vintage crowd, if you’re seeking a stock facade, then opt for 351W heads and an Edelbrock Performer intake manifold (paint it engine color!). Our message here is flexibility. You can build a higher displacement small-block without stepping up to a 351W block.