Why is it that I cannot find a legal bolt on exhaust package for my '84 Bronco? It seems that everyone makes it for an '87 and up... All I have found that is legal for it is a set of Thorley tri-Y headers or some Edelbrock tubular ones. I would definately need a better Y-pipe to make that worthwhile... and it has two cats in series on it! Looks like an AIR injection tube in between them, but it has rusted off... I would like to replace those with high flow jobs... or can I replace it with one that has the AIR tube?

Thanks!

Darren

 

The problem is that there are no shorty types available (at least I haven't found any yet) that directly bolt in place of the stock manifolds. There are a few headers that are "long tube" types, such as the Dynomax 85053/86053 ones. The problem is that if you use these there is added expense to remain legal in most areas. Since the long tube headers extend below the engine, and the factory crossover extends down and goes more or less into the pre-converter then the main catalytic converter. And the air injection pipe goes into the side of the main converter (as I recall). So, there is moving and fabrication required to make it legal...

So this is my thought on this. On my 1984 Bronco 5.8 HO, the manifolds don't have any additional parts installed EXCEPT for the left manifold has a heat riser valve between the manifold and the head pipe. The right manifold has a heat stove for the air cleaner. I thought to myself, looking at all the catalogs for headers, "Why are there headers for all those 5.8's with fuel injection, but not the carbureted models?"

Well someone sent me a set of 1994 5.8 Bronco manifolds last year, and I finally got around to comparing them to my 1984 manifolds (well the left one so far, since my heat riser just failed). The manifold appears to be the same shape and layout except that the 1994 models do not have the provision for a heat riser (I guess the Fuel Injected engines don't route any heat under the intake like the old carbureted models). The pipe diameter is larger on the 1995 manifold, but the bolt spacing for the head pipe retainer is the same distance from side to side (For unlike Chevy, only uses two bolts).

So this leads me to ask everyone here, does anyone know if there is any major difference in pipe routing between a 1984 Bronco 5.8 and a 1994 Bronco 5.8? If not, then why not simply find a donor later model truck to swipe the head pipe off of then get some headers for the later truck... In my case I have already swapped the factory system 2 cats for one high-flow cat and a large (but quiet) low restriction muffler. Has anyone done this? Are there any exhaust experts that can tell my why this is a bad idea other than the legal ramifications of not having that stupid broken, leaky, cracked, heat riser valve in the exhaust flow. And I already passed the emissions test without it since it only stays closed until the sensor tells the vacuum valve to open the flapper. It was broken and leaking so someone previous to me took it apart and used bolts to block the holes from the valve shaft.

I don't want long tube headers!