My '84 F-150 Is finally running smooth as silk. Let me start with a little history. I purchased the truck back in January, not running very well.
As most of you probably know, this year still had the carb. 300 six, but it is computer controlled with all the usual early emission do dads. The first thing I found out was the computers power relay was shot so the engine was running rich. I priced a replacement relay & the price gave me the incentive to take apart the old one & fix it. Now I had a working computer but many of its underhood components were either broke or frozen.
I replaced all necessary parts & the engine started to run a little better.
Next was the carb. The Carter 1bbl sounded easy enough to rebuild but with all those xtra's from the computer controlling it, this turned out to be far from easy. Once rebuilt, the engine still did not idle or run properly. A compression test revealed a leaking valve in #5 cylinder.
After having the head rebuilt, replacing all rocker arms, push rods, & lifters,I thought I was finally going to have a smooth running 300. I re installed the intake/exhaust to the head, installed the carb, checked all vaccum lines & wiring & started her up. To my dismay, the engine idled worse than before!
A check with some WD-40 revealed a leak in #2 & #5 intake runner where it attaches to the head. What went wrong? I was soo careful to clean all surfaces, line up the new gasket & torque down the intake/exhaust bolts.
Once again I removed the intake/exhaust. I found the lower gasket on both 2 & 5 intake had somehow moved & ripped during installation. Some of you probably know the replacement intake/exhaust gasket for these years are made up of 2 pieces. The exhaust is metal & composite & runs the entire length of the head. The intake gasket sits on top of the exhaust gasket & is made of composite material. This gasket is only joined to the exhaust one on the top, allowing the lower half of the intake gasket to just flap open. This is what must have happened when I installed the gasket the first time.
Speaking to some local mechanic I found out that Permatex makes Avaition Gasket Sealer that works very well with intake gaskets. I believe it's the only sealer that is impervious to gasoline. I purchased the avaition sealer & a new gasket, brushing on the sealer under the intake gasket to hold it to the underlying exhaust gasket. I also brushed on more sealer on the top of the intake gasket that makes contact with intake manifold.
I kept my fingers crossed after putting it al back together again. The engine idled & ran perfectly smooth!!! No more rough idle. No more miss.
After reading some other post's, I realized I wasn't alone with my intake manifold sealing woes. I hope my fix to this problem will help some other members keep their 300's running smooth.

 

Great post! Too many people see their engine run like crap and the first thing they think of is "rip off the emissions stuff". Yours is a terrific testament that an old engine can be brought back to "like new" without a Sawz-all.

 

Good job and great write-up.

 

Thank's Srercrcr. This truck was a true test of all my patience & brain power! The vintage 80's emissions were sure challenging. An example that comes to mind was the combination air bypass & air control valve. The bypass valve portion was frozen, feeding fresh air constantly to the exhaust. After replacing the hard to find valve, I found out the TAB & TAD solenoids were dead, so the new valve would not function. Just try & find these exact solenoids. I retrofitted some EGR vaccum solenoids from a 86 Lincon & they worked perfectly.
One of my cheaper fixes came from an old trans. dipstick tube that I used to replace the air pipe for the cat. that had long rotted away.
I figured that some very intelligent engineers at Ford spent many brain cells to make these early emission systems function, so the least I could do was preserve their work! Besides the truck now runs better than most pre-emissions engines I have seen.
I still say the hardest part of this project was to convince myself that a 1984 truck that I remember very well when it was new, was now considered a classic? How time flies!

 

Thank's Harte3. Gotta Keep Em Runnin!!!

 

Awesome! And a very familiar story (personally). It's fun getting these nasty running old 300s running glass smooth without ever needing to rebuild them. They usually just need a freshening up!