Ok,i purchased a 1984 F150 4x4 swb,FARM TRUCK that was to have a 302 and was supposed to run good,wrong,what i ended up with was a piece of crap!!!! so now comes the truth.This truck ended up with a 351w and i have had to pretty much rebuild the entire truck.front to back is new, i mean, really new!!! so here`s what happened.Only at the last minute just before i was going to sell it for what ever i could get i decided to try 1 last thing to get this engine running,firing order for the 351w instead of the 302,well that`s it right!!,yes......But,it will not rev up no matter what i do or have done.i need some real help it`s draining my wallet to death.so here is what i did and what i know,First,rebuild carb(ford 2bbl) non electric,new intake gaskets,valve cover gaskets,wires,cap,rotor,Brand new Dist,timing set, chain & gears,plugs,coil,pretty much everything in the ignition.What i have checked is the compression 120lbs across the board,don`t know if that`s any good.So today i checked the vacuum,at idle 20" but,when i rev it just past half way it starts to shake violently and the vacuum drops to 10",i even went as far as disconnecting the exhaust pipe to see if it was blocked,no luck.If any one can help me i would really appreciate it.it idles great and when you start to rev it up it`s great until you get to half way and then it`s over.

 

A 1984 302/351W... Do you have the computer-controlled feedback carb?

 

old style 2bbl non feedback.

 

Sounds like it's running out of fuel. If you force it and open the throttle more, does it pop back through the carb? If you let it idle for a little while, can you rev it in the very beginning, but then it starts stumbling?

If you can rev it for a little bit and then it stumbles, I think it may be a fuel supply problem. If you can never rev it, it always stumbles and never gets above half throttle, I would suspect clogged jets in the bottom of the carb, low fuel level in the carb bowl, or I have had a problem like this once, and I had the gasket miss-placed underneath the booster venturi assembly.

 

did that come with an electronic carb? if it did and you swapped for a conventional one, did you replace the ignition system with the computer controlled one it came with, or with a duraspark like you should? its real simple to tell, the duraspark has a vacuum hose going to it, the TFI (computer controlled mess) has a grey module screwed to the side of the dizzy.

when you try to rev it up, is the vacuum gage as steady as your foot, or does it shake

 

Right... merely replacing a feedback carb with a non-feedback, older-style variant will lead to all sorts of problems.

 

Well sometimes it`s best to just walk away.This morning i decided to just look over everything and i couldn't understand what was wrong,this thing is new from top to bottom and i`m a pretty smart guy,really i am....So,what i decided after thinking my self to death was how easy it would be if i could just figure this out,well i did...... Never have i seen this but he module was bad,i have seen them over heat and die or just be dead but never have i seen were half of the module was working.as of now it`s like it just woke up and wants to fly,man it sounds awesome,so if anyone ever comes across this here may be another simple fix for a lot of pain,Not 1 symptom ever lead me to believe this was my problem.