Good Evening,
It has been a few years since posting a new thread on this forum. I have been working on my 1979 Bronco so I have been preoccupied. I recently purchased a decent 1994 F-250hd, 351W, ZF5, 3.55, extended cab 4x4, and 8,800 GVWR. I also purchased a fiberglass work body known as a Space Kap plus. It allows me to stand in the back and access my service equipment. I am a Refrigeration service mechanic and in my opinion am building the ultimate service truck. I previously was in a Chevy express 2500 with the 4.8 LS Vortec. It was a great vehicle but I need more space. My old van would achieve 11 mpg consistently. I was within 1000lbs of the GVWR 8200lbs.

Currently my F-250 is at around 8,100 lbs. I have steadily fixed the truck up to the point where it has become a great daily driver and handles the weight and the height of the fiberglass Space Kap. At this point I will being tearing into the 351W. It has 270,000 KM on it and runs great. Truck Idles great and there is no noticeable major issues with it. While I am repairing the oil pan and front cover oil leaks I would like to add a few components to increase my low end power. I would like to make some noticeable gains from idle to 2000 rpm and also add a bit more top end as well. Keeping the power down low will also increase my MPG which stands at 9.8 currently. Here are my plans after reading a few threads on building power for the 351w.

1) GT40 Heads- I have a set of gt40p heads and I was thinking of rebuilding them. I also have an extra set of E7TE heads in need of a rebuild. As this is a work vehicle I would like to maintain the use of 87 octane. If I go gt40 will I have to purchase mid-grade or higher? Should I stick with the E7 heads and just open up the exhaust side?

2) 1.72 Scorpion Roller Rockers. I had installed these on my 1992 Bronco 351W with flat tappet block. It woke that truck up. They increased power and my MPG was improved. From a few threads I read the F4TE blocks with the roller cams don't respond as aggressively to the increased lift. What are your thoughts?

3) Exhaust- Currently I have the stock manifolds that tie into the torpedo cat under the truck. I have no muffler after that. Just a 2.5" side exit mid bed. Truck is on the quieter side which leads me to believe that if I remove the old catalytic converter and install a new high flow 3" system i will see some good gains.My 92 Bronco Had BBK headers tied to a 2.5 y pipe to a 3" system with a 3" x 18" Magnaflow muffler. That was much louder than my current f-250 above 2500 Rpm but quieter below that. I plan to build a similar system. I Need to do some more research to see which headers allow me to work with my gt40p heads. The BBK headers I used on my Bronco look promising with header plugs and wires. Does anyone know of a 351w truck header that clears gt40p plug angle?

4) Camshaft- Many threads point to the mustang gt roller cam to be a great upgrade over the stock cam. My question is will it build as much low rpm torque as the stock cam with 1.72 RR? Or will the mustang cam be even better with the addition of 1.72 RR for low rpm torque production?

Thanks for any thoughts on my plans. i will be posting pictures and thoughts along the way as I upgrade my F-250. I know many will say go diesel or 460 and don't look back. They are great motors but I have lots of working experience with the 351W and ZF5 and many spare parts. Also the 351W is the payload champ among OBS fords which means I can put more tools into my truck for work..

 

Here Is my current setup. Once i have it mechanically where I want I will be color matching the space Kap to the Truck.


F-250HD Service Truck.

 

Here Is my current setup. Once i have it mechanically where I want I will be color matching the space Kap to the Truck.


F-250HD Service Truck.

 

What mounting kit did you use to mount the spacekap to that generation ford. I have a 1996 f250 and looking at buying same spacekap.

 

I checked them out and their site said they are universal to any pickup with 6.5 or 8.0 bed. Move it back and fort to any different brands of trucks Nice rigs..

https://www.spacekap.com/model-compak/

 

So I called Space Kap and they told me they had no mounting kit for my model year. The mounting kits are just cut plywood and a front and rear header for the bed floor. The thing is that those mounting kits are not how the Space Kaps were always mounted.
The previous owner had an 05 3500 ram and when he got it new in 06 they just stacked a couple inches of rubber mats to ensure the Kap cleared the bed rails by an inch.
I used one layer of 1” heavy mats which allow the Kap to clear the bed rails by over an inch. I also used a cut 2x4 to wedge up against the bed header so it cannot slide forward to make contact with header. You then just engage the locks which press under the bed rails and force the Kap into the bed floor. I have been using it this way fully loaded for 4 months in heavy traffic and it hasn’t moved at all.