Oh my golly. Has it been two months already?
Here are links to my door panel plate as well as a couple shots of the ignition stuff under the hood. And, once again, it's an '82 not an '86.
http://i1331.photobucket.com/albums/...psb085e125.jpg
http://i1331.photobucket.com/albums/...ps954bf5e7.jpg
http://i1331.photobucket.com/albums/...psb75027ea.jpg
Thanks in advance for your input.

 

If there's a vacuum line on the distributor then it's the older DS-II version, lucky for you. My '80 had a 302/C4/2.75 rear and acted similarly to yours, but the C4 didn't have the converter slip like the C6 does. My problem was slightly taller tires, the 2.75 gears, and the 302 that made torque up high in RPM. Yours even with a C6 shouldn't be that bad considering the 300 makes more torque at lower RPM. I'd start by checking timing and carb mixture, that can make a world of difference. If it still seems underpowered, then I'd agree with Rogue_Wulff and swap to a lower ratio like 3.25. If you drive on the highway a lot I wouldn't recommend anything lower than that without an overdrive trans.

 

Mines an 84 4spd manual that has the computer and let me tell you 2nd only goes to 25mphs 3rd to about 35-40 mph and 4th 55mph at just a smidge above 2k rpms. I have stock tires and 3.08 rear end. It doesn't get any where fast but will haul wood and junk without a problem.

 

Something's amiss here. Mine hits around the same in 4th with stock tires and 3.55's. I'm thinking maybe your 3.08's were replaced with 3.55's as well. Is your 4th gear overdrive? If it is then it has to be even lower than that. Or your tach or speedometer, or both could be off.

 

Well I have learned that with a 30 year old truck anything is possible. Maybe I read the codes wrong too. As for the tach and Speedo I think there correct.

 

Pretty much the same with my 86 except with 31 inch tires. Indicated 60 on the speedo is actually closer to 67 and that's about it, though it holds it steady on hills as well. ~Bill

 

The 8th digit in your VIN is E which equates to a gasoline-powered 300 cid 6-banger with a 1B carburetor (light duty).

Trans K = C6 auto

Rear axle 01 = 2.75:1 ratio, 2,800 lb. capacity Ford-built axle

Your DSO code is 57 which means it was built for sale in the Houston region (not California).

What this all means is that you have a truck built for mileage and not towing or hauling (and not for original sale in California, which means no computerized stuff).

That being said, I still think something is wrong and that you should be experiencing better performance than you have; I can't imagine them being able to sell these things brand new if they had problems getting onto the highway.

Given everything, I think you should verify the ignition timing is being advanced as the engine RPM increases, that's my first guess.

My humble opinion thinks you should first check all the basics and make sure everything is operating as designed before placing blame on any one (or many) possible causes.

 

Of course though, highway speed limits were lower back then... But still, with that straight 6 it shouldn't have a problem getting up to speed. I don't know exactly what top end was on a 300, but the '80 in my sig would run 110+ all day long, just took a long time to get there.

 

Having 30-31" tall tires on a truck with a 2.75 ratio axle, is almost the exact same as having a 2.47 rear axle with stock ~28" tires. Of course, the bigger tires are also much heavier..... This gives you a real world RPM of around 1700 @ 55 (not counting loss in the convertor). Even with ~250 lb/ft of torque at that RPM, the 300 is not going to accelerate the truck with much gusto. It'll do pretty good at maintaining speed, but not so well at gaining speed.
I drove my 80 for over 16 years, and it had the 300/C6/2.75 axle combo. The first 10-12 years, it had 235/75-15 rear tires. Then stepped up to 31-10.50/15 on the rear. That made for a huge difference in how well it gained speed, once in 3rd/high gear. I can only imagine the effects of having the larger/heavier tires all around.

Having an engine that is not tuned well, and/or dragging brakes, will amplify this effect greatly. These trucks are not the most aerodynamic design either.
Restricted exhaust and/or choke not opening completely can also have a serious effect at highway speeds.

The 300 is a great engine. But ford had a habit of gearing them way too tall, in the quest for higher MPG numbers. This worked in the test environment, but not so well in the real world.
Wasn't bad for back roads and/or around town driving, but not so great for highway speeds.

 

I'm sorry, I have no input, I just almost spewed coffee on my screen reading how you don't trust your co-worker's advice because he drives a Chevy and drinks a lot! Like you can't decide which is worse! HAHAHA! Anyways, thanks for making me laugh. I hope you find your answer to your problem. I myself have a 1981 F100 Custom that frustrates me as well, so I may be in contact with you about questions if you don't mind!