Hey all. For $700 I picked up a new toy to play with - big aspirations at this point in the game. Check out some shots of the truck to see its condition. Cylinders have good dry compression - 130, 130, 130, 140, 150, 130. Having rebuilt my Saturn engine in the fall, and going a bit overboard, it's tough to get away from the whole make-it-perfect game ... basically, I'm thinking of pulling the head, milling it down to up the CR (apparently 9:1 is the limit for what is reasonable on a 4.9?), porting & polishing it, and maybe re-ring, replace rod bearings, and clean up the bore if I pull the pan off to get the pistons out. Carb also needs work, cause of a non-existent cold idle, and the way it really protests as it nears 3,000 rpms. And the shake while it's at idle & low revs is extremely annoying. So basically, I want it to run well, not feel so anemic, and also be able to get better than 12 mpg. It'd be a different story if it had a 600cm carb in it

So that's the outline as far as engine work - but I'm afraid the truck won't pass emissions because the cat is rattling around, and probably on its way out. I thought I saw the cat from the engine bay, but then I saw another cat-looking muffler under the cab ... do these have two catalytic converters? Also, the AIR pump injects in two spots in the exhaust, but why is that? Does it use the reed valve-type design?

I'm just trying to figure out what options there are for keeping this legal and reliable, while getting a healthier exhaust note out of it. My 1.9L Saturn is louder than this, as it is now

 

The compression is not bad for the year of truck, how many miles? Why mess with it til it needs fixing? From what I understand, the '86 had 2 cats (no idea why), as for the carb, if you don't have emissions, you could always change over to a two barrel. Do a search on it, you'll find lots of info, and BTW, welcome to FTE. Also check the stickys, lots of useful info ther also.

 

Hey, Brendo, click on User CP in the top-left and finish filling out your profile so we can see
where you're at, would ya?

There is also a forum dedicated to this engine, there are sometimes good people there, too:

Ford Inline Six, 200, 250, 4.9L / 300 - Ford Truck Enthusiasts Forums

 

Sure thing, I'll update my profile later on - running out to the door for work now but am eager to get more F150 juice first thing in the morn

I do have to keep everything emisions-proper for PA, which is fine - but what mufflers do I get as far as the dual-cat setup goes? So long as there are ports for the AIR, is that all that matters? Catalytic converters need to heat up before they are operable, so I really can't understand why one further downstream would help emissions, at all.

Oh, and the truck is to serve as a cross-country trip mobile. Ambitious plans include a camper / hauler combination for several friends to go to LA in. And, having redone my Saturn engine to better than factory specs, I kind of just can't get away from wanting the Ford to be near-perfect as well.

 

The second "cat" may actually be a resonator. They look like cats but just help to keep the sound down. Check your state laws. Example: here is GA if the vehicle is 25yo or older you don't need the emmissions stuff.

 

But it is still a violation of federal law to do so.

600CFM is a lot for this motor without extensive modifications (even then it may still be a lot)

Best bet, if you leave it like it is, is to rebuild the carb and give it a good tune up with a vacuum gauge. (fordsix.com has a good tutorial on that)

 

I don't get into this argument anymore.

 

There are 2 catalytic converters for the 1984-1986 4.9L carbureted engine. The 1st one is very close to the log manifold and the 2nd one has air injected just prior to it. It is not uncommon for members to report replacing both with one newer designed 3-way convertor and still being able to pass emmissions.

 

I don't argue over it, I just like to point it out to people, just in case one day our gov't has **** like aspirations for older trucks...

I don't have all the stuff on mine, but I am eyballing some defective equipment...

 

Cool, this was what I needed confirmation of. Why the dual cat design though?

And sorry for the confusion - I made mention of 600cfm carb in reference to guzzling gas. AFAIK the carb is original and so I shouldn't get 12mpg with a properly tuned setup. Check the pictures I linked to in the first post though, and it'll be clear this is far from properly tuned, heh

 

Earlier than 1984 on California Models.

The first catalytic converter is a secondary unit. The one farther downstream is the primary unit. Both basicly function the same way, one removes emissions, and the other removes that much more.

The newer catalytic converters and aftermarket converters are designed to take the place of both, so only one of the newer ones are used for replacement. Technology improved the design in later years...

The 300 does not use resonators from the factory. The muffler is quite enough.

Infact straight pipes are quieter on the 300, in my opinion, than some muffled V8s.

 

Unless, of course, that pipe happens to be cut off right underneath the passenger floorboard, like mine was..

 

I'm getting ready to replace the dual cat setup on mine with a single replacement from AutoZone. They have a single for $76, not to bad because I'm sure mine are stopped completely up due to the fact that I have no power anymore...

 

If they were stopped completely, the truck wouldn't run. But it could be restricted.

Think of the banana in the tailpipe on Beverly Hills Cop.

 

Cool. Thanks for the replies, everyone

Yeah when I redid my Saturn exhaust I got all Magnaflow - a high flow cat, 2 x 18" SS resonators, and a SS turbo muffler. It's definitely louder than I was expecting, but it sounds fantastic - rather muscley, regardless of being a 1.9L 4cyl. I wasn't expecting that

So, I'm thinking one Magnaflow model 34016 should suffice. These SS resonators go for pretty damn cheap - this with a turbo muffler will probably sound ballin on the 4.9L.

But, man, oh man, does this need a new valve cover gasket (among other things, heh)