The exhaust system begins at the manifold and header and determines your engine’s personality at the tail-pipe. Chances are good that if you’re reading this book you’re also interested in performance. Because this is an “interchange” book, the focus here is on stock to mildly modified exhaust parts and installation.
This Tech Tip is From the Full Book, FORD SMALL-BLOCK ENGINE PARTS INTERCHANGE. For a comprehensive guide on this entire subject you can visit this link:
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Single- and Dual-Exhaust Systems
When the small-block Ford was introduced in 1962, the only exhaust system available was a single vanilla muffler. Even the 1963 Fairlane with a 289 High Performance V-8 had a single-muffler exhaust system. The Hi-Po didn’t have dual exhausts until the Mustang received this option in June 1964.
The aftermarket offers exhaust systems for all Ford generations. National Parts Depot, Virginia Classic Mustang, Mustangs Unlimited, and Dearborn Classics, to name a few, offer a generous lineup of bolt-on exhaust systems that you can install yourself or have installed. Flowmaster, Borla, Magnaflow, Walker, and others have extensive muffler product lines.
If you own a classic Fox Mustang or perhaps a mid-1980s LTD or Thunderbird with 5.0L power, a wealth of great bolt-on exhaust system packages is available. For classic Mustangs and other vintage Fords you can select one of many off-the-shelf exhaust systems. Given a choice, opt for an off-the-shelf dual-exhaust system engineered to fit your Ford. If a system is unavailable, access to a good exhaust shop enables you to fabricate a custom-made dual-exhaust system with your favorite aftermarket muffler.
While you’re shopping for mufflers, consider noise levels that can damage your hearing and irritate those who live around you. Loud and obnoxious isn’t in style anymore. A soft throaty burble at your Ford’s exhaust tips is what’s in style. So always opt for an environmentally friendly exhaust system that gets attention without being offensive.
Classic Mustang floorpan reinforcement plates are available from Classic Tube for those planning a dual-exhaust system for a Mustang or Cougar. These stampings are identical to those that the Ford factory installed on Mustangs with dual-exhaust systems, and including brackets and muffler hangers. Muffler shops tend to use sheet-metal screws to secure muffler hangers to the floorpan, which often tear out when you cruise over a bump. The Classic Tube floorpan reinforcement system prevents that, offering solid security for a dual-exhaust conversion.
Arvinode Dual-Exhaust System
One of the factory performance exhaust systems now available in reproduction form is the limited- production Arvinode dual-exhaust system installed on 289 High Performance Mustangs between October 1964 and March 1965. It was originally manufactured by Arvin Industries for Ford and is available from Waldron Antique Exhaust and is an authentic reproduction of Ford’s original system. It has two acoustically tuned straight-through mufflers and two resonators that soften the bark.
When you’re on the throttle with an Arvinode dual-exhaust system, it gives your small-block Ford a nasty bark at the tailpipes yet it is not offensive in terms of noise levels. Everything you need to install this system yourself is there, including hangers and all hardware.
The reproduction Arvinode system was conceived by Dave Wallace, who managed to round up the original drawings. This system makes it easy to perform an authentic restoration on a 1965 Mustang with the 289 High Performance V-8. This system was installed on factory Mustangs for a limited time, but you can install it on any 1965–1968 classic small-block Mustang as long as you have 289 High Performance exhaust manifolds. Given access to a good muffler shop, you can modify this system to work with shorty or long-tube headers.
Manifolds and Headers
Small-block Ford manifold selection has never been generous. For the majority of applications one basic type of manifold for the 221/260/289/302 was available through the 1960s. As Fords changed in the 1970s, manifolds changed accordingly. If you’re building with performance in mind chances are you’re not thinking about exhaust manifolds.
The best stock exhaust manifold for the 221/260/289/302 is the 289 High Performance version. Ideally, you find a pair for the 1963–1964 Fairlane with an automatic choke heat stove, which are decidedly rare and nearly impossible to find. The 351W and 351C were never factory fitted with high-performance exhaust manifolds, although the 351W manifolds resembled those bolted to the 289 High Performance V-8.
The poor man’s Hi-Po manifolds are those for the 351W. The 351C and Boss 302 employ similar cast-iron manifolds because both have the same cylinder head. Other than variances for vehicle application, they are the same.
If you take a more conservative path, you want short-tube headers, or “shorties.” The most user-friendly shorties are headers from Ford Performance Applications (FPA) with a ball-and-socket collector. They have the best fit of any header in the marketplace.
These headers look factory original because so much goes into proper fit. If you have them ceramic coated in a charcoal or natural metal finish, they vanish alongside your small-block Ford.
Ford replaced iron exhaust manifolds with short tubular headers beginning in 1985 on the 5.0L High Output V-8. This is not a header to be used for performance purposes, but instead a restoration where authenticity is important. If you’re building a classic Fox-Body Mustang restomod, a good aftermarket shorty header is the best choice, which improves exhaust scavenging and remains smog legal in most states.
Post-1975 Ford vehicles typically have catalytic converters. Stick with a good, free-breathing catalytic converter, especially if your local area has tough smog laws and testing. Magnaflow and BBK both offer California smog-legal catalytic converter packages for the 1979–1995 Mustang GT and LX with 5.0L High Output engines. These are easy bolt-on cat packages you can integrate into nearly any aftermarket exhaust system.
Beginning with the 1966 model year Ford had to meet even tougher California emissions standards. Small-block Fords headed for California received the Thermactor smog-pump system. It is an exhaust emissions reduction package consisting of an engine-driven air pump, hoses, check valves, anti-backfire valve, and tubular air-injection manifolds tied to the exhaust manifolds. Air is injected into the exhaust ports to reduce hydrocarbon emissions.
Exhaust-air manifold check valves allow the flow of air in one direction only, which protects the pump when exhaust pressures become higher than pump pressure at wide-open throttle. The anti-backfire valve on early Thermactor systems operates based on intake manifold vacuum and throttle position. Failure occurs when the anti-backfire valve diaphragm or its check valves develop a leak and has to be replaced. Early Thermactor air-pump systems were fitted with a foam air cleaner element.
Although many think that the Thermactor robs power, it has never made much of a difference in stock engines aside from exhaust port restriction. The Thermactor employed a tubular air manifold for each cylinder bank from 1966 to 1974. Beginning in 1975, the tubular manifolds were eliminated and the air passage was cast into each cylinder head along the exhaust ports with external ports at each end of the head.
Thermactor parts are difficult to find. Yet, if you’re doing a restoration or must meet tough smog laws in your area, you must have the system. The Internet yields several sources for Thermactor emission system parts.
Later examples of the Thermactor system were equipped differently than those first systems introduced in 1966. Beginning in 1968 Thermactor air-pump systems were revised and fitted with air bypass valves, which were commonplace until the late 1970s.
By the 1980s, Ford had refined the Thermactor air-pump system to include air pump, air bypass valve, check valves, air manifolds and hoses, and air-control valve. This system was easier to understand and maintain because of its simplification and EEC. The 1980s Thermactor is more advanced due to its air injection at both the engine’s exhaust ports and at the catalytic converters. As necessary, Thermactor also vents air over-board, which can sometimes be heard in classic Fox and SN-95 Mustangs.
Written by George Reid and Posted with Permission of CarTechBooks