Early Bronco Engine Options
Engine upgrades really are fairly subjective. So much is dependent on how you plan to use the Bronco. If you go mud bogging or dune running then flat out horsepower and high RPM's fit the bill. If you like to crawl through boulder fields you're probably more interested in low end torque. And if you spend all your time on the street and want pure reliability, then a stock 289/302 or fuel injected 5.0 could be for you. Even the stock Bronco 6 cylinder has it's place, offering good gas mileage and rock solid reliability. With all that said the guide below should help give you an idea of the more popular engine swaps and what they might be worth to you. Again, the info is given in general terms and how you drive your Bronco will change which engine is most valuable for your needs.
Stock 289/302 or 170/200 - OK, admittedly these aren't engine swaps. But I show them more to give a baseline. There's nothing wrong with the stock Ford Bronco power plants. They're reliable and will last hundreds of thousands of miles if maintained properly. Simply rebuilding your stock Bronco engine is straight forward and cost effective. The downside is you're using 30 year old technology and fuel efficiency isn't the best.
351W Swap - People have been swapping 351's into early Broncos since the late 60's. It's the oldest swap and still a very popular way to get more horsepower and cubic inches into your steed. You need to understand that there's the 351C and the 351W. The 351C stands for Cleveland and although you can swap one into a Bronco, it's not as common. The 351 more widely used in 1966-1977 Broncos is the 351W (Windsor). The advantages of the 351W over the 302 include a stronger block and larger main and rod journals. Oh, and that extra 49 cubic inches of displacement doesn't hurt either.
There are a few issues to be aware of with the 351W swap. The deck height is about 1" taller than a 302. This may cause the air cleaner to hit the underside of the hood. This can be solved by installing a body lift, cutting a hole int he hood (with a scoop to cover of course), or getting an aftermarket hood (typically fiberglass) with a scoop or raised section built into it. You'll also need 351W headers designed specifically for the early Bronco. A new oil pan and accessory brackets are also needed.
5.0 Swap - The term "5.0" typically refers to the 5 liter engines found in late model Mustangs. For a Bronco swap it means replacing your carbureted 289 or 302 with a more modern, more efficient fuel injected motor. The benefits are substantial including better gas mileage, lower emissions, more power, smoother starts, automatic adjustment for change in altitude and no more stalling or flooding on steep hill climbs or sever off camber situations. It sounds great, and it is. But the 5.0 swap is also vry involved and requires a lot of research and money. The more you research and source parts yourself the less money you need to spend. Inversely if you have more to spend the swap can be made easier by purchasing one of the very comprehensive kits on the market. They've done the research so you don't have to. Just be aware that the acutal swap and hookup still takes a significant amount of time.
390, 428, 460 and other swaps - Where there's a will (and lots of money) there's a way. And many an industrious owner has found a way to get less conventional power plants into the hoods of their early Broncos. Some make sense depending on the owner and the way they drive their Broncos. But many times these swaps are more for the "wow" factor then any practical purpose. Most of the lesser used alternative engines are more trouble and cost then they're worth.
The 390 & 428 are both members of the FE big block family of Ford engines. While they have plenty of cubic inches and gobs of horsepower and torque, they're also extremely heavy. This added weight up front doesn't compliment the short wheel base Bronco very well and can contribute to steering and handling problems. And a heavy front bumper and winch and the weight distribution problem gets compounded even more. The FE engines also don't bolt up to the stock Bronco engine mounts or transmission. And if you find a big block transmission, then you'll need to fabricate a custom cross member and figure out how to mate up the transfer case, or find a different one.
The 460 is typically found in full size Ford trucks. In terms of swapping into a 1966-77 Bronco it falls in the same category as the 390/428 FE. It's large, heavy and requires custom fabrication to fit.
A Chevy 350 in a Bronco? Gasp! - Ethical issues aside, people have actually done this swap, although again, it typically makes much more sense to use a small block Ford. One main reason would be to more easily use a Chevy transmission, like the 700R4. It's a desirable transmission because it's a 4 speed with overdrive and has one of the best gear ranges around for an automatic. But to use a 700R4 with a Ford engine requires multiple adapters to engine and transfercase. So instead some people swap out the entire drive train (engine, transmission & t-case) with Chevy hardware.
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