My truck has been sitting for a while (months) and I've been bringing her back to life lately.

The idle isn't good at the moment and it used to be flawless. It starts just fine and takes a minute to warm up (normal for my truck) but then when it warms up the idle never really smooths out.

1 The exhaust manifold gasket bit the dust a while ago and it is even worse now. Could that contribute to the problem?

2 My main suspect is the carb (stock carter single barrel). I have owned this truck for many many years and I have never tuned it. It always ran so good so I didn't want to mess with it.

3 This last point may be a concern: When I decided a while ago to start bringing the truck back to life I thought it would be a good idea to do some basic work on the engine. The first thing I did was drain the radiator fluid, remove the t-stat, fill it with water and then run it to heat it up.

Then I drained the water (which was clean) and refilled the radiator with fluid. And, like a jackass, I forgot to put the t-stat back in.

Will this contribute to the idle issue?

I made a brief video so you can hear the idle. You can also see just how bad my exhaust manifold gasket is, smoke is coming straight out of the port. Oh and my hands aren't shaky, the truck moves like that with the idle screwed up.

300 I6 bad idle - YouTube

So what do ya'll think?

 

Heya,

How many years have you owned the truck? And that entire time, the carb's never been rebuilt?
It's possible that the carb simply needs to be rebuilt.

However, since you know the manifold is bad, (it looks like exhaust is coming out in the video), I'd start by changing that out. The intake and exhaust share a gasket, so if the manifold is bad, it could effect both of them. An intake leak will definitely cause idle problems like that.

No worries on the thermostat. All that'll do is prevent the engine from getting up to and maintaining operating temperature. This would effect performance on the road, gas mileage, etc, but not your idle like that. I'd definitely recommend putting in a thermostat though.

 

I think I bought the truck in '04 (was a teenager and it is the first vehicle I bought). However, the engine was changed out shortly thereafter - no later than '06.

I took it to a mechanic because it was knocking and decided to have the engine swapped out with another used one rather than a total rebuild. The mechanic said the ('new') engine came out of a city truck. I don't know how many miles were on the truck, but the engine ran great for years.

It shut down on me once, and that was cause of a clogged fuel filter.

Whether or not the carb is the source of the problem I am planning a rebuild.
I have two other Carter single barrels, I figure I'll buy a rebuild kit and rebuild one of those and put it on the engine. That way if I screw something up, I'll have the original carb that works enough to run the engine.

Will do. I have been putting it off because removing the exhaust manifold bolts is an intimidating task for someone like myself. I know I can get it done, but it's just one of those things that doesn't sound fun.

Thanks for the info. I'll probably put the thermostat in this weekend.

 

Ah, okay. I saw it was a '78, and sometimes when someone says "many, many years", they mean like 20 - 30.
If it hadn't been rebuilt in that many years, it's definitely overdue!

Sounds like you're starting about where I did on my Bronco. I didn't know much about vehicles at the time and the first two projects I had to do was A) rebuild the carburetor and B) swap out the intake/exhaust manifold.

Neither are as difficult as they seem. The 1bbl is a pretty simple little carb and the instructions are usually really precise.

With the manifolds, the biggest difficulty was simply keeping track of where all the stock vacuum lines went. Other than that, it was just.... REALLY... HEAVY... Watch out for your back pulling it out.

When you do the manifold, which I highly recommend, be sure to separate the intake and exhaust from each other and replace the gasket in between.
Then, you'll also want to have them resurfaced. They generally warp after a good amount of years. Generally, it's a good idea to have them bolted together when you do because it lines them up nicely with each other, and generally costs less because shops charge "per manifold". If they're bolted together, they count as one piece.

 

I thought (because of a visual inspection) that the two manifolds would come off separately. You're saying that they come off as one piece? That would explain why you said they're heavy.

Are you also saying there are actually two gaskets; one between the intake/exhaust and one between those components and the block?

Regardless, I will follow your recommendation of having them resurfaced. I am assuming this involves finding a machine shop then having them do the work? And they just need to cut the mating surfaces down so they are flush/flat...right?

One thing about that though. I want to buy a hedder. If I do that, should I have the intake resurfaced only?

Still unsure about the hedder. I am not planning on any mods for this truck other than that. I'm not willing to spend much more than $200 on a hedder, which leaves me with this option Hedman 89300 Hedman Hedders Standard-Duty Uncoated Headers
Problem there says it's for 2wd. I haven't researched whether or not I could make it work for my 4x4, but if I can I will.

Whatcha think?

 

They're generally really difficult to remove separately because the EGR pipe comes out of the exhaust manifold and goes into the intake. This is usually rust welded in place, exacerbated by the exhaust, so it can be really difficult to remove, especially while in the engine bay. As such, it's usually just easier to yank them out and work on them out in the open.
It's definitely doable to remove them from each other and remove them separately if you're determined though.

And yes, there's two gaskets. One big one that goes between the manifolds and the head, and a small one that goes between the intake and exhaust manifold.

Yeah, a good machine shop should be able to do that for you. It's definitely not something you can do yourself unless you have your own shop. They put a machine flat surface back on it by setting it on a large, flat belt sander until it's flat and shiny all the way across. It nullifies any warping that's taken place and gives you a perfect mating surface for the head again.


Another alternative to headers is to go with exhaust manifolds from an EFI era truck, especially if you plan on keeping the 1bbl. They're a huge improvement over stock and cost a fraction as much as a header. Best of all, they're designed, by Ford, for that engine.



You can get them pretty decently priced on Ebay, or from a local junk yard.


If those headers say they're only for 2WD, they probably are. The front axles are different in the trucks between 2WD and 4WD, and the headers may not be designed to wrap around them.

 

Okay, I think this sounds like a solid plan (which will save me ~$150). When I get the EFI hedders should I have them resurfaced along with the intake if it is NOS?

And finally, do you have any tips for removing the manifold bolts easily?

 

Put that money towards a 2.5" single exhaust.

The EFI exhaust manifolds don't warp NEARLY as much as the stock carb intake. You can check them for flatness with a straight edge. However, it certainly couldn't hurt. I've never seen any that are warped.

As for removing the bolts, I never really had an issue with it when I mine. Soak them for a few days prior with something like PB Blaster. Get a few different extensions. And then get a thin walled 9/16 socket. Some people have trouble with "fat" sockets binding against the intake and they can't get it off.

A basic 9/16 closed ended wrench can be handy for the bolts right behind the carb, since it can be difficult to get a socket on that one.

 

After this post I'm gonna bid on these:
New 87 89 92 94 96 F150 4.9L 300 Exhaust Manifold Set | eBay

Got another question for ya. How am I gonna connect the two outlets into the exhaust pipe itself? You have this set up in your pic, did you do that yourself?

 

Those look like they should work slick.

I did do my exhaust myself. This is the pipe I used and is a common piece.

Walker Exhaust 45166 - Walker Direct Fit Y-Pipes - Overview - SummitRacing.com

Keep in mind it's 2.5"



One thing to note is where the rear inlet is welded to the main pipe is often poorly done, so it's advisable to take a grinder and open it up more. When you look down it, you'll see what I mean.

 

That looks awesome. Do you know the standard size exhaust? I'm assuming 2.5" is bigger than what I have now. If so then no complaints from me!

You've been very, very helpful AB I can't thank you enough. I'll drink to your health and post updates when I get this all connected.

 

Glad to help. And thanks! I take all I can get.


I think the stock size is 1 7/8" on the carb motors. It's not exactly the highest flowing exhaust...

If you're interested, grab yourself a 2.5" muffler and cat, and a pre-made tailpipe and put a whole new exhaust on yourself. It's what I did on mine and it made a huge difference, even with the 1bbl. (I did the 4bbl a bit later).

Summit has most all of those and a selection of tailpipes. I think I did my entire exhaust engine to tailpipe for around $300. Way less than any shop around here.

 

Okay, bit of an update here. Parts came in and I see what you were saying; the rear inlet will need a bit of work:



Anyway, I removed the manifolds.



[Enter joke here]
The bolts actually came off really really easy, no problem at all.

Okay, so now I need to find the right gaskets. The parts store (NAPA) only has the 1 gasket. They said that it's a combo and it is the only gasket needed. I didn't buy it, but I'm not sure what to do. I'll check some places online tomorrow, but what is your suggestion?

I figure I'll get the bolts from ACE.

What about the EGR?

And the one thing I've kind of put off thinking about: what about the exhaust? Was your exhaust bolt on? I saw a kit on Summit like you are talking about.

 

First of all, WOW! I've never seen one of those Walker Y-Pipes with that poor of hole in the back. Usually there's some, but that's just plain ridiculous. I'd send that picture to Walker and say, "Are you serious!?"

Secondly, WOW, that manifold looks thrashed! I'm going to take a wild guess that that may have been contributing to your poor idle.



As for the gasket, the gasket NAPA has should work just fine (it's most likely the standard Felpro). However, if you want to go a step up, track down a Mr. Gasket #260. It's a good, high quality gasket. The downside to it is it's a one time deal. So, if you remove your manifolds sometime in the future, it can't be reused.

I'd recommend looking for a different source for bolts than Ace. They're usually way overpriced. If it's all you can find, though, be sure they're Grade 8 steel and that the guy knows what he's talking about. When I first did my exhaust, that's where I went, and they gave me some they guaranteed were "automotive grade" and two of them snapped in half before I even got them all the way down. They were expensive, too. About $3 something a piece.
I found another place that deals with nothing but nuts and bolts and got much better quality for around fifty cents a piece.

If you're using the stock 1bbl, you can hook up the EGR, but you'll need to make your own pipe for it. The rear EFI manifold has a port for it, but the pipe you have now won't match up.


Yeah, my exhaust was a complete bolt on. I bought the walker pipe, a 2.5" cat, 2.5" muffler, and then a 2.5" pre-made tailpipe. The cat and muffler were both slip fit, so all I needed was a piece of straight pipe to go between them, and a few exhaust clamps.
About the only tricky part to the whole install was hanging the exhaust. I had an exhaust shop do that for me to just button everything up.
I think it cost around $300 for everything all said and done (whole exhaust from the block to the tailpipe. Not too bad).

 

Those issues shouldn't be too much of a problem. I think I will contact Walker and/or Summit and give them a heads up.

Today I removed the exhaust manifold from the intake. It appears that the intake is warped. Check it out:

<a href="http://www.flickr.com/photos/78265658@N03/7178888172/" title="IMAG0020 by JDShimp, on Flickr"><img src="http://farm6.staticflickr.com/5350/7178888172_61d87bccab.jpg" width="500" height="299" alt="IMAG0020"></a>

<a href="http://www.flickr.com/photos/78265658@N03/7178893092/" title="IMAG0021 by JDShimp, on Flickr"><img src="http://farm6.staticflickr.com/5445/7178893092_1d7d518a84.jpg" width="500" height="299" alt="IMAG0021"></a>

So, uh, does this mean I need a new intake manifold?

Also, should I be concerned about the head if both manifolds bit the dust?