I have this thread going here

https://www.ford-trucks.com/forums/1804448-1979-ford-f-250-drivetrain-swap-questions.html

To show the progress with my truck.

As I am going through it to get it running, I have a few questions in the emissions. All this emissions stuff is new to me, as my previous Ford truck was a 1971.

I don't want all this complicated spider web mess of hoses running everywhere. My hope was to get an old Ford truck that consists of the basics: engine, tranny, switch, battery, starter, and, alternator. Simple. The emissions unnecessarily complicate things for me. With that being said, I would like to scrap it all. I don't understand how it works.

-From what I've read, the current factory carb is set up for the emissions and removing it now would cause it to run poorly and foul plugs. Is this correct?

-my ultimate plan, if the motor ends up running strong and being solid, is to switch it over to an Edelbrock Proformer Carb and Intake. If that switch happens, the emissions should not be needed at that point.

-today I dropped the rear fuel tank to ensure it had no rust. I found that my factory tank had the emissions vent in the top of the tank that goes to the front of the truck to the charcoal tank. I wasn't even sure what that was before today. How does that system work and is it worth leaving on the truck?

-the choke heat riser tube that runs from the manifold to the air cleaner is shredded. Same with the air cleaner hose duct that runs from the air intake to the air cleaner. If I switch to the upgraded Edelbrock carb/intake, these would no longer be necessary as I'd just have a stand alone air cleaner on top and not the large factory unit. What do people do when they make this modification and no longer use the heat riser tube?

-the previous owner already installed headers to glass packs (Blue Streak variety) with a dual exhaust. No catalytic converter (if one was on there from the factory). He had also taken the belt off the smog pump. If the smog pump is not connected to run, what do I need to do to ensure the engine runs smooth now (before any carb/intake upgrade)?

I appreciate any guidance from the smarter fellas on this board! This process takes the patience of Job.

 

Get this book, Bypass Emission Controls. Your 79 should be very similar to the 77 info. The book lays out exactly what parts you'll need, how to do it step by step, & how to tune it when you are done. It also details how all the various systems work. It will answer all your questions.

I have a 79 F150 with a 351M. The air pump was removed decades ago when it seized up. The convertor came off around the same time. The rest of the stuff is still in place. The truck runs fine, currently 194,000 miles.

https://www.ebay.com/itm/37719085472...Bk9SR5qE4aDUZw

 

In '79 you would have had all the emissions including the converter.

You can easily eliminate all of it , most did on day one. the tube on the air cleaner isn't emissions it was for a faster warm up. you don't need a new intake just throw your EGR plate away, screw a bolt in the hole and put a phenolic spacer in it's place. sounds like your air pump and convertor are already gone so it's just a matter of how much farther you want to go. if you want you can have nothing but your vacuum advance and power brakes, and PCV for hoses left. the PCV is a beneficial emissions device I'd keep that but you don't have to.

 

Thank you for that info! I ordered the book.

 

Thank you for the info. I ordered the book suggested above and will go through it all when I do.

Would I not need a new intake if I go to a 4 barrel carburetor? That's what I was referring to, eventually jumping to a 4 barrel. I know nothing about all of that so I'll be reading a lot and picking up info on the fly through this forum. I really appreciate you fellas with the advanced knowledge.

 

I would keep that system. I don’t think it hurts performance and can help with fuel odors instead of a vented gas cap.

The PCV system is a must for me. I would have thought your last truck had that also.

 

It may have had the PCV, but I owned it 28yrs ago. I wish I still did. From you and others, it sounds like the PCV will be a keeper. I will listen to knowledge! Thank you for the info.

 

Everything (Gasoline ) has had a PCV since the 60's, it is an emissions device but it does some good and hurts nothing.

If you want a 4V you need a new intake but if you just have a stock 351-400 you need to decide if it's worth it, you won't gain much. if you do, you'll want a smaller CFM carb and preferably a Holley.

 

My gas tank has a vented cap, and no containment. It will at some point as I’m not a fan of walking past the back of the truck and smelling gas; makes me think there’s a leak, although I suppose it is.

Tossing PCV usually equals sucking more oil into the intake if you still route vent tube to base of carb for evac of crankcase, or “vent to atmosphere” and get a build up of acids and moisture in your oil. That will also depend on how much vacuum the truck builds at idle, running, and under load.

 

I bought a new 1979 F-250 4wd with a 400 and 4-speed back in June 1979.
I removed the cat with a "test pipe:.
Removed the AIR system and EGR valve and it didn't make any difference in any way.
Not power or gas mileage.
I removed the cat because I was out 4-wheeling with a couple of friends and lit some sagebrush on fire with it.
I ended up having some fender well hedders, 2.5" pipes and turbo mufflers and once again, zero change.
But it did sound better.

I would hate to live some place like CA that still requires that crap.

 

@Rubiranch
I'm still stuck in the '70's, and i remember those Wildflower hippie chicks and even one found me, and we've been together over 40-years.
Omg, and you bought yours NEW with a 12k or 12,000 mile warranty. Chevy small blocks needed valve jobs at 35k miles. _ LoL
I stripped all of the California smog equip off of my '77 AMC Jeep cj-7 in early '82. I had dual exhaust installed around then also, and, kept the single exh Cat and tailpipe.
All of that went back on around '86 for when the Bi-Annual Smog was initiated. It just passed smog in July of 2025. _ yeay, that was a real headache retuning.
My '77 F350 Crew Cab pickup doesn't require a Cat from what i remember. I have it registered in another County that is Bi-Annual exempt. Same with my '78 E250 Van.
Because of the 8,900 lb gvwr of the E250, I hadn't been required to install a Cat _ _ _ yet.