Originally Posted by 1TonBasecamp

Another aspect of headers is that the thin metal tubes transmit much more sound than a thick cast-iron manifold does. And the thinner (cheaper) materials are louder than the thicker ones. That's why a selling point in advertising more expensive headers is the thickness of the tubing.
But even a thick tube header is louder than a stock exhaust manifold in most cases.

x10 on checking for leaks though. They are notorious for this.

Headers also lean out the mixture and are often followed up by installing larger main jets in the carb. They may have gone overboard on the jet sizes, or just the opposite.
If you let an engine run too lean, you can get what's called lean-misfire in which the combustion process is not efficient or complete not because there is too much fuel mixed with the oxygen, but because there is too little.
So either too rich OR too lean can make your exhaust smell pretty bad.

In the mid to late-seventies they were just learning about how to reduce emmissions and one popluar way was to run the mixtures very lean. Which is one of the reasons that more and more powerful ignition systems were brought into play.
But since yours is obviously pretty well "de-smogged" and also running headers and an aftermarket carburetor, the tune is up in the air until you start messing with it. No way to tell just by an outward look what jetting or meter sizes the carburetor was outfitted with (most just use them as-is out of the box) or whether it was compatible with the better breathing exhaust, or whether the ignition system is doing it's job.

Hell, it might just need a tune up!

And speaking of de-smogging and stuff, can you see a PCV valve sticking out of the passenger side valve cover? This would be a plastic/metal metering valve with a 3/8 hose running to the base of the carburetor. I see what looks to be the venting cap on the driver's side cover, but can't make out what's there on the back of the passenger side.
If it's just another cap or breather, then you really should install a PCV valve and plumb it correctly (we can walk you through that if it's needed) to keep the engine healthy and running well for the long term.
Like the evaporative emmissions system, it's one of those very beneficial devices to come out of the smog wars. One of the best actually.

Bottom line is that you can actually install a catalytic converter on an old truck (I did) but you need to make sure the engine is tuned very well and stays that way. A poorly tuned truck could wreak havoc on an expensive cat pretty quickly.

Good luck.

Paul

Originally Posted by farmallmta

All this advice being given and none of you know a single detail about this engine. What you don't know includes, among other facts:

What cubic inch displacement for sure
What year the engine was produced
What, if any, modifications have been made to it
If rebuilt, how it was done
Anything at all about the exhaust system
Service, maintenance, and repair history of the engine and truck

And yet you're all troubleshooting, and totally in the dark. There is no mechanic worth his salt anywhere in the world who would start blurting out advice like you guys are doing without first needing to know at least the information listed above. All you have to go on is two videos including general engine noise, and poor audio quality at that. And his wife's comment that the truck smells. And yet, you advise.

Valve lash: the clearance in the valve train, necessary for solid lifters whether they be flat or roller. Why are you advising him to check valve lash when you have no idea if the valve train has solid lifters? The only way hydraulic lifter valve trains have gap in them is if the hydraulic lifters are partially collapsed due to low oil pressure or mechanical failure, and adjusting it out is not the fix. Where in his description of the engine does he tell us it has solid lifters such that you can start telling him about valve lash? If he doesn't have solid lifters, stop misleading him by talking about valve lash. You're only making things confusing.

A guy buys an old truck. It smells, meaning combustion or heating vapors are getting into the cab. His wife is noticing. And you start telling him to stuff rags up the exhaust pipe? My god, he needs to get that truck to a competent repair shop NOW, have it towed in, before carbon monoxide kills somebody.

Sorry for the rant if it makes you feel bad. But seriously, this forum sometimes reminds me of a bunch of half-wit teenagers standing around drinking beer in the shade on Saturday afternoon telling bullshiite fix-it stories to one another: "yeah, this one time the truck really smelled bad, man, and I stuffed some rags up the exhaust pipe and adjusted the lash on the hydraulic lifters, then went out and blew the doors off a Camaro that had everybody else in town running scared." Jeez.

To the original poster: ignore everything you've had suggested to you here. Get your truck into a good repair shop and let somebody qualified get it right for you. This bunch of yokels here is just going to cost you time and money and possibly just make things worse.

Originally Posted by farmallmta

All this advice being given and none of you know a single detail about this engine. What you don't know includes, among other facts:

What cubic inch displacement for sure
What year the engine was produced
What, if any, modifications have been made to it
If rebuilt, how it was done
Anything at all about the exhaust system
Service, maintenance, and repair history of the engine and truck

And yet you're all troubleshooting, and totally in the dark. There is no mechanic worth his salt anywhere in the world who would start blurting out advice like you guys are doing without first needing to know at least the information listed above. All you have to go on is two videos including general engine noise, and poor audio quality at that. And his wife's comment that the truck smells. And yet, you advise.

Valve lash: the clearance in the valve train, necessary for solid lifters whether they be flat or roller. Why are you advising him to check valve lash when you have no idea if the valve train has solid lifters? The only way hydraulic lifter valve trains have gap in them is if the hydraulic lifters are partially collapsed due to low oil pressure or mechanical failure, and adjusting it out is not the fix. Where in his description of the engine does he tell us it has solid lifters such that you can start telling him about valve lash? If he doesn't have solid lifters, stop misleading him by talking about valve lash. You're only making things confusing.

A guy buys an old truck. It smells, meaning combustion or heating vapors are getting into the cab. His wife is noticing. And you start telling him to stuff rags up the exhaust pipe? My god, he needs to get that truck to a competent repair shop NOW, have it towed in, before carbon monoxide kills somebody.

Sorry for the rant if it makes you feel bad. But seriously, this forum sometimes reminds me of a bunch of half-wit teenagers standing around drinking beer in the shade on Saturday afternoon telling bullshiite fix-it stories to one another: "yeah, this one time the truck really smelled bad, man, and I stuffed some rags up the exhaust pipe and adjusted the lash on the hydraulic lifters, then went out and blew the doors off a Camaro that had everybody else in town running scared." Jeez.

To the original poster: ignore everything you've had suggested to you here. Get your truck into a good repair shop and let somebody qualified get it right for you. This bunch of yokels here is just going to cost you time and money and possibly just make things worse.

Originally Posted by Filthy Beast

On the "ticking" ----have you pulled a valve cover yet? I'm asking because the "ticking" sounds like you might have roller rockers........they're know to make noise, sounding a bit like a sewing machine.

Let us know what kind of rockers you have.

I won't comment on the fuel/unburnt hydrocarbons/exhaust smell as other have pretty well covered it. 1Ton makes some good points, as usual....

You could check yer fuel pressure - Edelbunks don't cotton to more than 5 - 6 psi and it could be yer burnin' extra fuel if the pressure is too high.

Originally Posted by JBMorrey

I can't take my 2014 Lincoln to a Brake Check without them finding a ton of repairs that they "recommend" I can't imagine what they would say if I took my truck to them!!