If you were around for the detuned Mustangs in the 1970s, you can appreciate what it felt like when Ford brought back the Mustang GT in 1982. While it was a good-looking ride, it wasn't much on performance. In fact, it was more show than go with its 5.0L High Output V-8 with a 351W marine performance camshaft and, believe it or not, a Motorcraft 2150 two-barrel carburetor under the aluminum dual-snorkel air cleaner.
But for 1983, Ford stepped up the power to 175 hp, thanks primarily to a Holley 4180 four-barrel carburetor. Although 175 hp isn't a page-turner in these days of 700hp Shelby Super Snakes, it was a big deal in 1983 because it was a major improvement over '74-'82.
Holley carburetion atop a small-block Ford in 1983 was surreal considering the strict federal mandates of the era. The early 1980s was an era of vacuum hoses, check valves, smog pumps, exhaust gas recirculation devices, and stifling single catalytic converter exhaust systems. For Ford to actually fit the Mustang with a Holley carburetor was a big deal, mainly because of Holley's century-long ability to design and build great performance carburetors.
Waltz out to any racing event-be it drag racing, road racing, dirt track, marine, etc.-and you will primarily find Holley carburetors. One reason is because Holley performance carburetors are easy to tune and service. For the '83 Mustang 5.0, Holley engineers took on the challenge of designing a 4180 version with both emissions and crisp performance in mind.
What makes the Holley 4180 different from its aftermarket 4150/4160/1850 cousins is the tamper-proof metering block that makes it virtually impossible to adjust the idle air mixture. Also different are the primary boosters, which are annular discharge to reduce emissions. Conventional Holley primary metering blocks will not interchange onto the 4180. However, with minor modifications, secondary 4150 metering blocks will interchange to improve wide-open throttle performance. Center-pivot Holley fuel bowls will also interchange if you use Nitrophyl floats instead of the brass types. It is important to note that '83-'85 Mustangs probably won't pass a smog check with these bowls because doing so eliminates the evaporative emissions system, which, by the way, has no bearing on power output.
Although we associate the...
Although we associate the 5.0L High Output V-8 with Sequential Electronic Fuel Injection, during 1983-'85 the engine had four-barrel Holley carburetion. Beneath the dual snorkel air cleaner is an emissions-friendly, Holley-engineered four-barrel carburetor.
This is a remanufactured Holley...
This is a remanufactured Holley 4180 on the 5.0L High Output V-8 in an '85 Mustang GT. There are variations between '83 and '85 centered mostly around emissions and performance improvements. The '85 49-state and '84-'85 California emissions version of the 4180 has a vacuum choke pull-off diaphragm that reduces emissions during cold start operation.
Don't let the 4180's hoses...
Don't let the 4180's hoses and connections intimidate you. Each has an easy-to-understand purpose. Shown here is an evaporative emissions hose to the secondary fuel bowl, which keeps fuel vapors from escaping to the atmosphere. Below the secondary fuel bowl is the exhaust recirculation (EGR) valve. A sticking EGR valve will cause poor idle quality or stalling because manifold vacuum is what operates this valve during deceleration. The valve allows exhaust gasses to pass from the exhaust side back to the intake manifold. If the valve sticks in the "recirculation" position, it creates a vacuum leak and poor performance.
This is the fast idle solenoid,...
This is the fast idle solenoid, which is energized when the air conditioning compressor is engaged. When the A/C is on, it bumps up the idle up to prevent stalling. There's also a compressor cutout switch, which opens the compressor clutch circuit at wide-open throttle to both protect the compressor and remove the load from the engine. This solenoid/switch combo is very hard to come by today.
Poor operation isn't always...
Poor operation isn't always the carburetor. Rough idle can be caused by a leaking carburetor base or spacer gasket, a sticking EGR valve, or leaking vacuum hoses. Don't give in to the temptation of removing the spacer and EGR valve. You should be environmentally responsible and aim for the cleanest exhaust possible. Keep the EGR valve shaft dressed with a high-temp penetrating lubricant every time you do an oil change for smooth operation. Replace the EGR valve whenever it sticks or the diaphragm fails.
The '83 Holley 4180 is basically...
The '83 Holley 4180 is basically the same as '84-'85 with minor calibration and connection differences. What makes it different than a conventional Holley is the anti-tamper logic. Absent are the idle air mixture screws in the primary metering block like we see with 4150/4160/1850 Holley carburetors. They were relocated to the base plate and sealed with lead to prevent tampering. The good news was evaporative emissions from both fuel bowls, electric choke, and fast idle solenoid for air conditioning use (not seen here).
Holley 4180 carburetors are...
Holley 4180 carburetors are identified by Motorcraft tags, although many have been removed and discarded during a rebuild.
Identification is also possible...
Identification is also possible via Ford part numbers and the Holley list number stamped into the air horn. Part numbers should read E3ZE for '83, E4ZE for '84, and E5ZE for '85. If you have an E4ZE with the choke pull-off diaphragm, you've found a California emissions '84 carburetor. There will be variations depending on when your Mustang was built and where it was delivered new.