How's it goin. I have an '02 F-250 5.4 CC 4X4 and it has about 110,000 miles on it. I am currently deployed AGAIN and while the truck sits at my dad's place until I return, I want to have some work done. I am going to have the bottom end rebuilt (along with better rods). I was also interested in swapping on a set of the 4V Navigator heads. I know I will have to change intake, exhaust manifolds/headers, and do a different tune. Is it a bolt on swap with those parts (and other bolt on parts) or is there machining involved? Or will it just not work. I know anything's possible but just trying to figure out if it's something the average gearhead could do.

 

The Navigator heads are just about the least effective off all the 4V heads, next to the A and B split port heads.

A set of 99/01 (Cobra, Continental) or 03-05 heads (Mach, Marauder, Cobra, Aviator, Falcon Boss 290 & Boss 302) would be a much better bet. I believe the 03-04 Navigators even switched over to the 03-05 style heads.

The only issue I am aware of with swapping the 4V heads onto a 2V iron block is one coolant passage. You'll have to research it a bit, but I believe it actually has to be opened up in the 2V block and that is relatively easy.

Beyond that everything will bolt right on. The 4V combustion chamber is quite large (52cc) so a PI 2V piston with it's 17cc dish will provide a rather sizeable compression drop, somewhere in the mid-to-low 8s. Too lazy to figure it out at the moment. If you're staying n/a and you are already rebuilding the short-block go with either a stock 4V piston or an aftermarket piston with about a 2cc dish (or flat top) to get a ~10:1 CR.

 

Thanks. I was hearing that the Navigator heads were really good for low end torque. I was doing some research on some heads for a mod motor swap on my Mustang and saw some articles and it looked like those heads did better for low end torque than a lot of the other ones. It's going to be NA for now but will probably see about a supercharger with about 6-9 psi. It will come when I can afford to upgarde the fuel system the way I want to after some other mods (gears, exhaust, tune, CAI). Also, I thought the Aviator heads were close to or the same as the Navigator heads but I'm probably gettting those confused with some other ones, I've lloked at so many different ones I can't keep track.

I am also planning on getting the heads ported, probably should have mentioned that first. My goal here is a lot more low end torque, not high revving horsepower. The gear should help out quite a bit, too.

 

The Navi heads aren't better for anything. The 99/01 and 03-05 heads have both have 177cc intake port volumes (03-05 have some improvements on the short side Ford learned from the FR500 heads) and better flow at all lifts than the Navi heads. The Navi heads have an 184 cc intake port volume (less velocity) with some fairly substantial flow obstructions around the port divider. The 177cc heads will provide more torque than the 184cc heads in any app.

If all you are looking for is torque I would find a set of 04-05 (8 thread) 4V heads and leave them stock. Those heads out of the box flow enough to support 400rwhp n/a. Porting will generally only add intake port volume, not something you want to do when looking for a low-end/mid-range biased powerband. The trick to making low end torque will be found in compression, cam specs, cam timing, and the intake manifold.

Aviator heads are identical to the 03-04 Cobra, Mach 1 and Marauder heads. I *THINK* the Navigator switched over to the 177cc 03+ heads in 2003. The 184cc Navi heads from 99-02 were most definitely nothing like the Aviator heads.

 

Great, thanks for the info!