I have an 86 F250 460 4x4 I recently installed a fresh engine. Built the truck for hauling quads, trailers, firewood etc. After a proper break in i loaded my quads on the trucks flatbed and hit the interstate for a 20 mile jaunt to my favorite trail. To my dismay I noticed a serious lack of power when climbing. RPMs just won't come up and I find myself losing top speed. The engine was bored .040 over, heads redone, installed an rv cam with edelbrock performer intake and 750 carb. Runs great otherwise, just was expecting to pull a hill with a load and still have some pedal to spare.
I'm a gas engine guy, don't care what anyone says I don't trust an engine without spark plugs.

 

A few things come to mind and in no order.
What gear ratios are you running and the size tire?
What RPM is the motor turning and at what speed going down the hi way?
What is the RPM range spec. of this RV cam?
What timing chain/gear set did you use and how was it setup?
What exh system are you running from heads out to the tail pipe?


Any 1 or combo or all can kill power but not knowing what you have we cant point you where to look to get more power.
Dave ----

 

That was the first thing that came to my mind. Stock replacement 460 timing sets have the cam timing retarded so you should use either a '72 or older or a '88 and later fuel injected timing set. Using the original type replacement set for a '86 will really kill your low end torque, especially with a performance cam. Also, where do you have your ignition timing set? Is the advance mechanism connected and working properly?

 

What transmission are you using? It's going to have to kickdown and rev, or you will have to downshift a manual. The rear barrels on the carb will never open up without higher rpms.

 

Not sure on gear ratio other than its stock for an ext. cab xlt lariat, T19 4spd (no granny) with 235/85/16 tires on factory rims.
Going 65-70 at 3000rpm on flat road is fine, slightest incline and top speed falls, a give it more throttle the engine starts to stumble.
Unable to get to my cam papers right now so no help there.
Got a cloyes double roller timing set that had 3 keyways in it, a guy I know told me about the retarded timing so I used the advanced timing key per the timing set instructions.
Stock exh manifolds and stock pipes to muffler. Previous owner had a large 2 into 1 muffler installed.

 

Ignition timing set to factory spec. i.e. whatever the under hood sticker recommended. 8 degrees is the number that keeps popping up in my head.
The vacuum advance operates properly.

 

Did you pay as much attention to the transmission and differential(s) as you did to the engine ?

 

That carb should start moaning as you push it to the floor. I don't know how much weight you are pulling, and how steep the hills are, but you should hear something happening under the hood if you have it to the floor and the rpms are up.

The only driving experience I have had with a 460 is a stock 460 efi with a zf 5 speed. Pulling a 40hp tractor on a trailer up route 56 over the mountain to Vesuvius, it had to be shifted down to 3rd gear to make it. It's a pretty steep mountain and that tractor was decent sized.

 

Please clarify what you used here....

retarded
straight-up
advanced

 

Apologies that didn't come out right. The timing set had 3 key ways, one straight up (middle) one to retard timing (left) and one to advance timing (right). I used the key that advanced the timing to improve torque.

 

As I said earlier the drivetrain is all original, so to answer your question: no I didn't pay any attn to transmission and differentials. What would you suggest I look into?

 

Found the paper that came with my cam. Its a sealed power CS1086R

 

For your gear ratio, look on the VIN sticker where it says "axle".
39=3.55
35=4.10

Have you checked fuel pressure and float levels?
What kind of oil are you using? It needs to have at least 1,500ppm ZDDP (zinc) to prevent the lifters from eating the cam.

 

I thought the T19 was an up graded T18 that has a granny low that is synchronized?


Now with the 3000 RPM at 65-70 speed it is hard for "me" to know if you have an over drive trany or the rear gear giving you that speed/RPM reading?
I also don't know why you have the issues you have?
Dave ----

 

This, a T19 is a granny gear transmission.