Advice on Carb + Intake Swap for 300 Straight Six

[tommyg]

Hi All,

New here, but I've been searching around for a little while to find some info on the subject:

Truck:
1986 F-250 4x4. 300 Six Engine, 1bbl carb.

It currently has the stock setup that's kind of in rough shape, it runs but not well. Definitely needs the carb rebuilt or replace, and there's a ton of smog and vacuum line stuff missing. I was hoping to find someone that has done a similar job on this specific setup. I'm looking at getting this kit from Jegs:
https://www.jegs.com/i/Offenhauser/750/6019-DPK/10002/-1

But before I drop the cash, I want to make sure I'm on the right track. I want to eliminate what I can from the smog/vacuum setup if possible since most of it is rotted or missing completely. The EGR tube from the header is badly rotted also, so I'd rather eliminate what I don't need in that regard.

My main questions are:
1) Is this carb intake setup the right choice (it says 2WD models only on the Jegs site, but plenty of reviews have said that it fits fine on the 4x4 as well)
2) What can I eliminate from the vacuum system and what do I need to keep? (obviously the brake booster, but not sure after that)

If there IS another post about this that I missed I apologize, I couldn't find one. I've been cruising over on Ford Truck Enthusiasts too and haven't found what I'm looking for.

Thanks in advance.
-Tom

[Gary Lewis]

Tom - Welcome!  Glad you joined.  

You probably haven't seen the email I sent you asking you to go to the New Users Start Here folder, read the guidelines, and then start a new thread/topic to introduce yourself.  But the main issue is to give you a chance to read the guidelines as we hold everyone to them.

Where's home?  I ask because we have a map (Bullnose Forum/Member's Map in the menu) and we'd be happy to add you if we had a city/state or a zip.

On what you need in the way of vacuum systems, if you are eliminating the feedback system, meaning replacing the carb and removing all emissions systems, take a look at the page here: Documentation/Under Hood/Vacuum Systems.

And if you are doing all that you'll not only need to replace the carb but also the distributor.  That's because you should have a EEC-III system with a TFI ignition system on the side of the distributor, and if so it is controlled by the computer.  And when you neuter the emissions systems the computer gets its knickers in a twist and locks ignition timing to whatever you have dialed in as initial timing.  No advance means poor performance and economy.

Also, without EGR you should change the timing curve in the distributor, so you should look for a pre-EGR distributor.  Perhaps someone has a suggestion on that.

[myrl883]

I'm gonna get hell for this, but a 302 is a perfect fix for a 300...

[Rembrant]

myrl883 wrote

I'm gonna get hell for this, but a 302 is a perfect fix for a 300...

LOL, it's funny for a couple reasons, but one is that I've been reading people complain for years that the 302 was a terrible truck engine haha. I have a mild fascination with the 300 six, but I too have been thinking about swapping it out for a 302...lol.

[Rembrant]

tommyg wrote

2) What can I eliminate from the vacuum system and what do I need to keep? (obviously the brake booster, but not sure after that)

I know you're looking for a different carb and intake, but to answer your vacuum question, I just purchased a cheap YF on Amazon ($69?) and I currently have ONLY the brake booster connected to vacuum. The only other thing I will be connecting is the distributor advance. (I also have my 302 set up this way...brake booster and distributor advance are the only two things I have connected)....well, I guess you can add PCV on both engines. Edit: Just realized after I posted the video that I didn't even have the booster connected in that one lol, but I did connect it shortly afterwards.

[1986F150Six]

Welcome to the forum, Tommy!

That kit is a lot of $$$!

The 4.9L/300 engine is a work horse, not a quarter horse... there are those who [me, for one!] love its unassuming work ethic. It does what it does without complaining, as long as you don't mind a leisurely pace. By the way, just for trivia sake, the 4.9L/300 engine was offered by Ford in trucks only and up to the intermediate duty range [F600]. That is because of its low RPM torque delivery. On the other hand, the 5.0/302 has more horsepower and get up and go at higher RPMs, but was not offered in anything larger than a F250.

If emission testing is not an issue, I recommend you replace the carburetor with a pre-emission Carter YF and replace the distributor with a recurved Duraspark. Use Motorcraft sparkplugs specified for FI engines [1987-1996]. What you will end up with is a reliable engine with good efficiency.

The EGR tube, which you mentioned, can be removed and the threaded hole in the EGR spacer plugged with a 3/4" piping plug. EGR by itself, is a good thing, but if not functioning can be worked around. In the previous paragraph, it was mentioned that a recurved distributor will be needed... that is because without a functioning EGR system, the ignition timing will be too far advanced under cruise conditions and pinging likely will occur.

Good luck with your project!

[Sac79]

A guy asks specific questions about a fancy kit for his 6 and everyone responds with 'swap in a V8'... I'm disgusted!

Or keep it stock... David.

Each to his own. If you're sold on the headers, check out the kit from Clifford Performance, https://cliffordperformance.net/store/ols/products/68-ford-240300-combination , same price and I've heard they have excellent customer service. Also, the intake manifold is already plumbed for heat.

The reason the kits are recommended for 2WD only is clearance issues with the headers. (carb and intake is not an issue) I have seen many examples in 4WDs though. You might just have to grind a little on the frame.

I decided against going that route mostly to save money. Supposedly the EFI manifolds will get you close to the header performance. Can't say if that's true, but it's good enough for me.

As Gary mentioned, biggest additional issue is going to be the distributor. You probably want to budget for a DSII swap or change to a HEI distributor(like I did). That would leave you with vacuum for the brakes as you mentioned, PCV and distributor. I kept my stock intake, so I also have vacuum for the snorkel.

Of course the smog stuff will depend on your local/state requirements.

[myrl883]

You get alot more power for alot less cash! And they run smoother, too. 300 is a solid workhorse, but I'm just not a 6 cylinder fan.

[FuzzFace2]

On the vacuum what Cory posted is right but if you have AC, Cory is north of the border and AC is not really needed, you will need to hook that up to manifold supply.

If I was you before dropping 2K try this.
You will need a dist. even with the kit you posted or the Clifford kit.
Either the factory DSII dist., box on the fender, wiring, and coil.
OR
Do the HEI dist. as it has everything built in and just drop it in.

So with the dist. taken care of spend the $70 on the YF carb, remove the emission junk (EGR pipe & plug) air pump, vacuum lines other than posted above.
See how it runs and if you don't like it keep the dist. and sell the carb / manifolds and buy the kit you listed.

My 300 is using a DSII factory dist. and factory YF carb and intake manifold but .....
I am using EFI exh. manifolds.
I just bought the cheap carb to replace mine as I was having issues but over the weekend I took my carb apart, cleaned it good again and checked & adjusted and it is working great again.

Vacuum lines: Power brakes, carb to dist. advance, HVAC (I have AC), PCV, and vapor canisters under battery (I for got this above).
No air pump, no EGR hooked up as it is plugged off but in place as a spacer.

I like my 300 and its low RPM power. I also built it to pull my open deck car trailer if need be.
Now if I can get a little more MPG out of it, mid 14's now, I would be a lot happier!
Dave ----

try this link https://www.ford-trucks.com/forums/forum52/

[tommyg]

Thanks Gary, new member requirement has been rectified. Obviously I got excited and just started spilling my guts out as soon as I joined. Forgive me.

[tommyg]

1986F150Six wrote

The 4.9L/300 engine is a work horse, not a quarter horse... there are those who [me, for one!] love its unassuming work ethic. It does what it does without complaining, as long as you don't mind a leisurely pace.

Agreed. I really just didn't know what my options were. I've clearly found the right place. I have no qualms about keeping the stock setup if I can get it functioning properly. I have found very affordable rebuild kits for the YFA carb and even just buying another one isn't bad. I may need another header still, I had it off in the Fall and I tried every trick in the book to get that EGR tube out of it, couldn't get it. New ones are only about $175 and it looks like they come pre-plugged, so that could be a decent option. I really don't want to spend that much on this one portion of the truck, so I'll be trying these other suggestions first for sure.

My vision for this truck is quitting my day job, getting a trusty old hound, and just driving around the neighborhood with my dog doing handy-man work for my neighbors. Maybe it's just a fantasy, but it sounds pretty sweet to me! Not sure the Mrs. would agree....

-Tom

[1986F150Six]

May I offer some reading material of a long journey with a similar [engine] truck...

https://www.ford-trucks.com/forums/1325963-gas-mileage-recipe-4-9l-300-a.html

[Gary Lewis]

No prob, Tom.  But thanks.

On the exhaust, if you can't get the tube out I've bent them over and crimped them tightly and it has worked.  Not the best, but it worked.

[FuzzFace2]

What we posted is guessing you don't have smog check in your area.

I would not put any time or money into that YFA carb as it is some what controlled by a computer(feed back system) and if any part of the system is bad the computer freaks out and goes into 'limp home mode".
Same goes for the dist., it is (timing) controlled by the computer and locks down if in limp mode.

Again the dist. has to be changed out if you keep the factory YF carb (non-computer) and the cheap Ebay carb you would be good there.

On the EGR tube, is there enough to cut the tube, flatten the ends and bend them over to seal it?
Then you would not need to deal with it. If you have a torch you can also heat the part the threads go into red hot the it should un-thread if the bending does not work. Heat would help on the flat / bending also.

Now if you wanted a little more power, cant say how much?, you can go with EFI exh. manifolds.
They flow a little better than the log manifold on the motor now.
But that brings some issues. The set up you have now the 2 manifold are bolted together, the exh. heats the intake up when cold. If you go with the kit is also does not have a way to heat the intake manifold.

I think someone posted the Clifford kit came with a plate to pipe hot water to heat the intake.
You can find this plate on Ebay also, that is where I got mine and I use EFI exh. manifolds.
Heating the intake floor helps keep the air / fuel mixed. If to cool the fuel drops out of the air and pools on the intake floor and drips into the cyl.

What may be more important than heating the intake floor is running hot air to the factory air filter assy.
This hot air helps keep the carb from icing when it is cool and damp out.
With the EFI manifolds this is hard to do because there is no tins that the factory had on them to hook the hose to for the heat to get from them to the filter.
I do run the factory air filter but no hose so it gets what ever heat it can.

I live in NC and drive my truck all year round, not everyday, so it can be 20*f when I take the truck to work in the morning and 60*'s on the way home. I have only had it stumble 2 times in the 5+K miles I have on the truck that might have been icing of the carb, other wise it been good.
AC not hooked up yet in this picture but you can see it looks factory stock other than no smog stuff.

This is what it looked like when I bought the truck.

Dave ----

[tommyg]

FuzzFace2 wrote

This is what it looked like when I bought the truck.

That's exactly what mine looked like. Where does one get lucky enough to find a factory style filter housing like that? I feel like I've looked everywhere and haven't had any luck. I can't stand that stupid little bolt-on that seems to be the only alternative for the 1bbl carbs. The most common answer is 'junkyards' but there really aren't any within striking distance of RI. It's all suburbia here, not enough space for junkyards.

FuzzFace2 wrote

What we posted is guessing you don't have smog check in your area.

I would not put any time or money into that YFA carb as it is some what controlled by a computer(feed back system) and if any part of the system is bad the computer freaks out and goes into 'limp home mode".
Same goes for the dist., it is (timing) controlled by the computer and locks down if in limp mode.

Again the dist. has to be changed out if you keep the factory YF carb (non-computer) and the cheap Ebay carb you would be good there.

So If I drop in an HEI distributor as suggested, then I can continue to use the YF carb that I have?

I'm not worried about smog here. You don't need an inspection to ride with antique plates here if it's only used for "leisure activities" according to the DMV. My neighbor has a 60s Impala with antiques on it and he said there's no enforcement on how much you drive with that type of registration.

[FuzzFace2]

tommyg wrote

FuzzFace2 wrote

This is what it looked like when I bought the truck.

That's exactly what mine looked like. Where does one get lucky enough to find a factory style filter housing like that? I feel like I've looked everywhere and haven't had any luck. I can't stand that stupid little bolt-on that seems to be the only alternative for the 1bbl carbs. The most common answer is 'junkyards' but there really aren't any within striking distance of RI. It's all suburbia here, not enough space for junkyards.

FuzzFace2 wrote

What we posted is guessing you don't have smog check in your area.

I would not put any time or money into that YFA carb as it is some what controlled by a computer(feed back system) and if any part of the system is bad the computer freaks out and goes into 'limp home mode".
Same goes for the dist., it is (timing) controlled by the computer and locks down if in limp mode.

Again the dist. has to be changed out if you keep the factory YF carb (non-computer) and the cheap Ebay carb you would be good there.

So If I drop in an HEI distributor as suggested, then I can continue to use the YF carb that I have?

I'm not worried about smog here. You don't need an inspection to ride with antique plates here if it's only used for "leisure activities" according to the DMV. My neighbor has a 60s Impala with antiques on it and he said there's no enforcement on how much you drive with that type of registration.

On the air filter I am a member on another truck forum that has a "for sale" area and someone was parting out 70's trucks and IIRC they use the same filter housings, that where I got mine from.
Now note the later 80's 300 six motors used a "normal looking" filter housing that would work also.

I think we have a WTB (want to buy) area can ask in there.
The other is Ebay and Craig's list.
On the list you may get lucky and find someone parting out a truck.

Oh I hear you on the junk yards as I lived in CT, 10 miles from the NY line on I95, up to 6 years ago and the yards scrapped anything older than 10 years.
Dave ----

[tommyg]

Bringing this back to the top as I work through things. I bought an HEI distributor and YF carb to attempt the more frugal route laid out by a few of you. Distributor seated in pretty well after some wiggling and profanity. I think I've gathered enough from other user posts to sort out the wiring for it, a Bosch style relay is on the way. The carb is next, but I had a few questions:

1) The plate that the carb mounts onto with the ports for the EGR and the vacuum pump...is there an older alternative for that which doesn't have those connections, or should I just plug them all somehow?

2) I can get rid of this coil now right? The HEI takes care of that?


3) I can also remove this mess of vacuum lines and electrical connectors? Anything need to be saved here?


Thanks again, this forum has been a wealth of info so far.

~Tom

[FuzzFace2]

1) On the EGR I find it is easier to just plug the openings.
Unless the EGR leaks you can just remove and plug the vacuum line.
If the metal tube is in place and not leaking just leave it.
If it is leaking if you can get the adaptors out pipe plugs should screw in.

2) Yes you can remove the old coil.
As for the rest of the wiring I would wait till the motor is running and can drive it to know all is ok.

If you want to run the motor before you get the relay run a jumper wire from the battery + to the HEI and if all is good when you crank the motor it should start & run.
To stop just remove the wire.

Again once running then you can take your time, trace the wires and remove them.
Yes even all them relays on the back of the valve cover you have marked.
Dave ----

[Brock]

tommyg- how did this carb/dist/relay project of yours work out?  I am trying to decide on a good carb for my 83 Bronco so I appreciate any insights.