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V8 Conversion Information
If you have a tired 289 or 302 or need more horsepower and torque, the 351 Windsor is the way to go. You may get better mileage with a Windsor than a stock 289 / 302 due to more torque and lower RPM. A 351 Cleveland doesn’t have enough low range torque for four wheeling. Clevelands require very expensive custom radiator, headers and exhaust. Hard to find 100+ octane gas is also necessary. So, unless you intend to drag race at 5,000 to 8,500 rpm, a Windsor will out perform, out pull, out climb, and get better mileage than a Cleveland.

A 69-70 2V or 4V Windsor is best, a 4V having 10.5:1 compression or a 2V, 9.5:1. Before you swap, see if the 351 has a 3 bolt harmonic bal-ancer. If it has a 4 bolt, you’ll need a 3 bolt harmonic balancer for a 69 Windsor. If you can’t find a 3 bolt, you can use a 302, 3 bolt balancer by re-marking the timing marks. Reuse your 302 water pump, pulleys, belts, etc. using the power steering adapter bracket #3160 & alternator bracket #3161.
The 351W rear main is larger, so the stock 302 pan won’t work. An Oil Pan Kit, #3103, is needed to clear the front differential. Most Windsors have the sump in front which is bad for four wheeling. Your engine could run out of oil as you’re climbing a hill! Our pan has a rear sump. Even with this pan, to avoid damage, your Bronco must be lifted 2- 3 1/2”.

To complete the conversion, our Headers are designed to take into consideration the extra 1 1/2” height of the heads. They don’t rub the firewall and if you need to remove the starter, you can leave our headers in place. CAUTION: Don’t try to use your 6 cyl transmission with the V8. There are several problems and it’s not strong enough to handle the power.

SWAPPING A 6 CYL FOR A 302 / 5.0L OR 351W: YOU'LL NEED:
#3100, or #3102 Headers
Oil Pan (351W) or Oil Pan (302)
Radiator with Bracket Kit
#3107 Lower Radiator “L” Brackets
#3114 Rubber Engine Mounts
#3115 Motor Mount Brackets
#3160, #3161 Adapters (351W only)
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Long Tube Headers 289/302/351W Painted, 1966-77 Bronco Classic Early Ford
Headers 289/302/351W Black Hi-Temp Painted, 1966-77 Bronco

A design that has stood the test of time. Made in the USA, our headers are one piece construction (not sleeved) with equal length tubes for maximum horsepower and torque. Designed so the starter can be removed with the headers in place and to clear the steering and clutch linkage. Made of 16 gauge, 1.5” diameter tubing for smooth flow into the 2.5” final diameter collectors, they follow the same route as the stock exhaust system. Utilizes a 3/8” thick flange for strength and to prevent gasket blow out. They fit 289, 302/5.0 and 351W/5.8 conversions. Compatible with C4 and AOD automatics and manual transmissions. C6 transmissions will require modification. Will not work with GT-40P heads. If running an NV3550 or AX15 transmission, using our headers will require a custom intermediate pipe to work with the new transmission crossmember (not available from Duff's).
The Duffy's Original Headers with the driver side design updated in 2001 to fit better with our #5350 Radius Arms. Come with hardware, premium gaskets and instructions.*

+As of May 2018, these headers come painted with a Hi-Temp Header Paint. They start as black but after heating a few times settle in as more of a dark gray matte finish. (They can be lightly scuffed and top coated with other high temp finishes.)

*The regulation of emissions production, noise levels, and safety standards is undertaken by the federal government, each of the fifty state legislatures and by many local municipalities, towns and counties. California Vehicle Code Sections 27156 and 38391 prohibit the advertising, offering for sale, or installation of any device which modifies a vehicle’s emission control system unless exempted. James Duff headers have not received an exemption from these code sections and are not legal for sale or use in California on vehicles originally equipped with catalytic converters. It is illegal, except for vehicles only driven off-road, to remove or otherwise render inoperative any emission control device on regulated motor vehicles. In the other 49 states, it- is the responsibility of the ultimate consumer to check federal and local laws to determine if JDI products are legal for use on their vehicle.

Currently out of stock until Fall 2019.


Classic Early Ford Bronco 1966-77 Ceramic Long Tube Headers 289/302/351W V8 Duffy's Original
Ceramic Coated Headers 289/302/351W, 1966-77 Bronco

A design that has stood the test of time. Made in the USA, our headers are one piece construction (not sleeved) with equal length tubes for maximum horsepower and torque. Designed so the starter can be removed with the headers in place and to clear the steering and clutch linkage. Made of 16 gauge 1 1/2” diameter tubing for smooth flow into the 2 1/2” final diameter collectors, they follow the same route as the stock exhaust system. Utilizes a 3/8” thick flange for strength and to prevent gasket blow out. They fit 289, 302/5.0 and 351W/5.8 conversions. Compatible with C4 and AOD automatics and manual transmissions. C6 transmissions will require modification. Will not work with GT-40P heads. If running an NV3550 or AX15, you will need custom intermediate pipes to clear the new transmission crossmember (not available from Duff's).
The Duffy's Original with the driver side design was updated in 2001 to fit better with our #5350 Radius Arms. Come with hardware, premium gaskets and instructions.* These feature a inside and out metallic ceramic coating that resists temperatures up to 1600° F. They are incredibly rust, chip and abrasion resistant; lower under hood temperature; and have an "polished/aluminum" look that does not blue.

*The regulation of emissions production, noise levels, and safety standards is undertaken by the federal government, each of the fifty state legislatures and by many local municipalities, towns and counties. California Vehicle Code Sections 27156 and 38391 prohibit the advertising, offering for sale, or installation of any device which modifies a vehicle’s emission control system unless exempted. James Duff headers have not received an exemption from these code sections and are not legal for sale or use in California on vehicles originally equipped with catalytic converters. It is illegal, except for vehicles only driven off-road, to remove or otherwise render inoperative any emission control device on regulated motor vehicles. In the other 49 states, it- is the responsibility of the ultimate consumer to check federal and local laws to determine if JDI products are legal for use on their vehicle.

Currently out of stock until Fall 2019.


2-1 Early Bronco Exhaust FAQ
2-1 Exhaust FAQ

Frequently Asked Questions-

What comes in the kit?
Driver & Passenger Head Pipes, Y Pipe, Mid Pipe, Tail Pipe, Muffler
Long Rubber Hanger, 1 each Long & Short L Brackets, 2-2.25" Exhaust Clamps, 4- 2.5" Exhaust Clamps, 2-2.25" Stainless Band Clamps, Hardware & Grommets, Donut Gaskets for manifolds (#3061 kit)

How do I know which options are best for me?
Click here to watch Monster Mike walk you through the options and accessories
No two Broncos or Bronco owners are alike, so we made this kit customizable to better suit your individual preferences.

What header finish should I choose?
Click here to watch Monster Mike walk you through header finishes
  • Black painted for a tight budget, no heat or rust concerns or if you'll need to customize.
  • Stainless for show quality good looks, no heat concerns or customizing.
  • Ceramic finish or show quality and best heat reduction in engine bay. The most durable hi-temp finish available

What muffler is best for me?
Click here to watch Monster Mike walk you through the muffler choices
  • Jones Full Boar- Classic Flowmaster 40 Series sound for budget pricing
  • Flowmaster Delta Series-Great Flowmaster 40 Series sound but without the drone
  • Cherry Bomb Pro- Agressive Deep Tone for that deep lumpy sound
  • MagnaFlo- Mellow Deep Sound that really wakes up at high RPM's
How long does this take to install?
A weekend is fairly standard for most home mechanics. Please read install instructions to see if you are comfortable with what is required.

Can I do it by myself?
Yes, but having a helper is nice when hanging the tail pipe.

What tools are needed?
Cordless impact drill, 17/64 drill bit, tape measure, silver or white paint marking pen, 3M green tape, 5/16", 3/8",1/2", 9/16", 5/8", 11/16", 17mm, 19mm wrench and socket, hack saw, cut off wheel or vertical band saw, rubber mallet, vice with pipe or soft jaws and two jack stands to hold up muffler & tailpipe during mock up.

My pipes don't fit together, what should I do?
Pipes are a very tight fit so they don't leak. Check for burrs and check pipe ends for damage. Call us if you need help!





Water Pump Bypass Hose V8 Engine Conversion 90° thermostat Ford Small Block
90° Water Pump Bypass Hose, V8
Our Price: $11.85

Water Pump Bypass Hose with a 90° bend molded in to go with our 90° Thermostat for all 289/302/351W V8. Necessary for most Bronco II, 83-97 Ranger or 91-94 Explorer V8 Conversions.


Alternator Adapter Bracket 351W 1966-77 Classic Early Ford Bronco V8 Engine Conversion
Alternator Adapter Bracket 351W
Our Price: $16.50

This bracket attach the 302 alternator to the 351W heads. They retain stock 302 mounts and use the same belts and pulleys. Shown with 3160 Power Steering Adapter.


Power Steering Adapter Bracket, 351W 1966-77 Classic Early Ford Bronco V8 Conversion
Power Steering Adapter Bracket, 351W
Our Price: $16.50

This bracket attaches the 302 power steering pump to the 351W heads. They retain stock 302 mounts and use the same belts and pulleys. Shown with 3161 Alternator Adapter.


Lokar Throttle/Kickdown Bracket for 86-93 Ford EFI Mustang EGR Stainless Black Midnight
Lokar Throttle/Kickdown Bracket for 86-93 Ford EFI Mustang EGR
Our Price: $18.95

Ford EFI Bracket fits 1986-93 Ford 302 and 351w fuel injection systems that have installed the Mustang EGR spacer.This stainless bracket mounts in the stock location for easy installation of the Lokar Kickdown Cables and Throttle Cables. This uses the #2342 Cable. Does not fit BAP throttle bodies. Available in Polished Stainless or Black Stainless.


Quik Latch Billet Air Cleaner Keeper
Quik Latch Billet Air Cleaner Keeper
Our Price: $27.00

For decades, people have been securing the air cleaner to a carburetor with a wing nut. Spinning it on and off is slow and often results in dropping it! Replace it with a specially designed mini latch that is a perfect finishing touch to custom build. Requires modification to the air cleaner to fit the latch button. Will not work on stock carb without mod. Diameter of latch: 1.23” stud: 4.125”
Stage 8 Header Collector Exhaust Bolts V8 V6 6 cylinder 289 170 351w Ford
Stage 8 Collector Bolts (6)
Our Price: $29.95

Ordinary Header bolts can be a real pain to keep tight due to the expansion and contraction that headers go through. No one likes getting in there and busting their knuckles if they don’t have to. We swear by these (not at them)! They use a patented locking system that won’t come loose.
90° Thermostat Housing Bronco Ranger Explorer Thermostat housing 90° outlet Early Bronco, Bronco II, 83-97 Ranger 91-94 Explorer V8/5.0 Conversion
90° Thermostat Housing
Our Price: $29.95

Thermostat housing with a 90° outlet for your 289 302 351W Small Block Ford V8 in Early Bronco, Bronco II, 83-97 Ranger or 91-94 Explorer V8/5.0 Conversion.