I have a 1994 F-150. I have a 300ci. I6. I just bought this truck about a week and a hlaf ago. It is in fantastic shape. My exhaust rattles and has a definite shake in the mid range RPMs (3000-4500). I am guessing the RPM range because I don't have a tach. Well, I am looking to replace the headers and exhaust here in the immediate future. What would you all suggest? I am getting a dynomax dual exhaust setup but I have no clue what to get for headers. I want to get a K&N filter as well because I have heard that they help when combined with headers and exhaust.

 

Check to see if the heat shield on the muffler isnt causing the rattling noise .

 

>Check to see if the heat shield on the muffler isnt causing
>the rattling noise .
That is what it is. I know that sound for sure. Thanks!

 

Just so you know - acoording to many people the stock dual exhaust manifolds are already close enough to headers, and they probably flow fine. Headers are generally for higher-RPM driving (to let the large amount of gasses escape easier), but you don't have a high-RPM engine. Your "3000-4500" numbers aren't mid-range on these engines, they are very high ranges. Midrange is 2000 RPM. SUre, you can beat the hell out of it to try to get 5000 RPM, but I can almost guarantee you that what you thought was "3000-4500" was actually 2500-3500. Past that the engine gets so loud that many people shift anyway.

 

So your saying if I stick with my stock manifolds I should be ok? Will a new exhaust help me any with my mileage. I don't beat on this truck at all so the engine rarely gets abused. I am only getting like 17-18 MPG regular driving (to and from work)and when I drive highway (70-80 MPH, I live in central Michigan) It is actually lower. I used to have a Buick LeSabre and that is pretty much why I have no clue about the RPM range. Thanks!

 

[updated:LAST EDITED ON 23-Apr-02 AT 02:59 PM (EST)]I think you'll be ok. The most restrictive part of these trucks' exhaust isn't the manifolds but the two cataltic converters, followed by the muffler.

Before spending the money, spend some good time reading all the archived straight-six posts from people. What I get when I read them is that these are low-RPM work engines that don't respond well to just a few modifications. A whole tear down and rebuild can make them really different engines, but that doesn't seem like that's what you want to do.

For better fuel mileage on the highway you probably ought to realize fifth gear isn't always the optimal gear for highway driving. You're better off keeping the engine in or near its max torque, so trying to drive in fifth at below 2000 RPM might use more fuel than driving in fourth would. (I have larger than stock tires, so my operating RPM is lowered per any speed... fifth gear is almost useless even on the highways.)

Remember, too, that you're driving the equivalent of a side of a barn against the wind, so keep it at more like 65 to 75 and you'll probably get better mileage. You bought a slow-lane work truck, so those speeds you were used to with a car probably ought to be brought down a bit. You traded speed for a vehicle that has a predictable engine and fuel mileage empty or overloaded.

Proper tuning will get you maybe 1 to 3 more MPG, but then that's the wall you're going to hit. On good days I get 18 to 20 on the highway.

 

Gammadriver is right in what he said. Also, those 17-18 MPG are about average for a big blocky truck pushing through the air. If you bring it down to 65-70 you are pushing through less air, less need for as much power = drop in fuel usage. Have a look at your exhaust manifolds. I know that the 95-96 manifolds are two piece and are very good in their design because they don't have many sharp turns or bends which create turbulence. The older manifolds flow a little bit worse, but are still good for stock pieces. I was interested in getting headers for my truck from Cliffordperformance.com but i was talked out of it by people who have used them on here because they don't improve much power over the stock ones. I don't believe that the 94s you have are the same as my 95s though. If my memory is correct, it was a one piece maybe? someone else will have to grab that one but, I think a 95-96 manifold will fit on yours. You can find new ones on ebay, type in Ford 300 in a search. It will probably not be worth the effort to install them though.




Primary rig is:
95' F-150 EB 300/6 5 spd with 4" Superlift, MSD, Ram Air, Gibson Exhaust, 32" BFG Muds
NEW PICS IN MY GALLERY!! :-)


Then theres:
88' F-250 Superduty 351 + c6
95' Mercury Cougar 4.6L V-8
80' E-350 300/6 and a
3 spd column shifter baby. Top speed, 65mph, Go Baby Go!

The newest addition to the Ford family is a 99' Mustang GT 4.6L