I am just completely crazy for my 86 F250 with its big six and manual trans. But... Its idle is ruff and the fuel economy dismal. Must be the carb.So what carb to use? And the manual trans is just about two gears short of making sense to me. I am always reaching for another gear. Will one with more gears bolt up to the old 300?
dont later F150's have a 5 speed? mines a 2wd 86 4 speed overdrive. it gets ok fuel economy for what it is, around 17 ish mpg.
ford trucks forums helped me figure out ive got an older oem carter carb on my engine with the stock 86 computer controlled ignition. so im berkeleying baffled as to why it still gets that good of fuel mileage and generally runs well. seems the hot ticket is to swap to an older carb and vacuum controlled distributor. you also need some wiring harness from an older truck. look up DS2 conversion on the ford-trucks.com forums.
sorry i dont have any real world self experienced information, somehow my dumb ass has managed to keep the truck running pretty well that i dont bother shopping for the conversion parts myself.
Holley did make a standalone tbi designed for inline 6 motors, and they show up once in a while. The jeep guys also have a well documented installation using GM v6 parts.
Bellhouse bolt pattern is standard windsor. Later ones had the 5 speed OD(M5OD-R2). My '93(EFI 300/6,5 speed, 4x4) would get 20 highway, 15 mixed. I would love to see what a 2wd with a tonneau and an air dam can do.
I believe Summit and Jegs both have a 4-bbl intake, header and cam kit for the 300. I'd plop either a 390cfm or 500 cfm carb on it; 500 if you drive it hard and 390 if it's more of a DD.
I had a '94 F150 with a 300 six and 5-speed manual trans. That was one silky smooth engine.
I assume you're familiar with FordSix.com?
Why not rebuild the carburetor you already have? It must have worked originally, and it will be cheaper than buying a new one.
Can you get a spreadbore intake for it?
Most carburetor problems are ignition related.
Those single bbl. Carter carbs like to vibrate apart on the 300 six. Put a kit in it w/ new gaskets and loctite the screws.
Those were still current when I worked for Ford, the idle will never be smooth with the single Carter. That's because the end cylinders (1 and 6) are so far from the carb opening they tend to 'starve' at idle. Once you get rolling you don't notice it. The multi point injected motors are much smoother and as a bonus make more power. Now, keep in mind the old thing is tough as nails but in stock form is no powerhouse, even the FI versions aren't very punchy. They also don't get great gas mileage. What they WILL do is run till the sun cools to a cinder and tow anything you put behind them.
Ford made 3 speed (3rd is 1:1), 3+1 (3rd is 1:1, 4th is o/d), 4 speed (4th is 1:1) and 5 speed (4th is 1:1, 5th is o/d) boxes for those. Any of the o/d boxes will help with the grab another gear thing.
I have a 3+1 trans sitting in my shop outside Macon GA that I'd let go reasonable-like for a GRMer if you want to go that route. Pm me if you're interested.
What gearing is in the rear end? That won't change your carb issues, but it will keep you out of the right lane of highways.
Dan
What sort of mileage are you currently getting?
We have an 82 for a shop truck. Idled like crap and got ~9 mpg. Ended up having a large crack in the carb housing and was just dumping fuel on the ground.
Mine is the 3 + 1 trans. First gear for crawling only. I am guessing that it has a 4:10 rear but will find out. Have never actually measured fuel economy but estimate 10 MPG. Definitely a momentum vehicle that seems unkillable. I do love the thing. It just feels that it should have more oomph and better economy.
6cyl engines with carbs... Bah... Put the 4 bbl manifold with throttle body EFI... lol
I too am a huge fan of that engine. From a benchracing stand point, I have always wondered if the BMW I-6 stuff could be part of a megasquirt conversion for one. Silly and probably impossible, yes.
Just grab two sets of triumph (3 cylinder) itbs and mount on a cut stock intake, ported of course. Run mega squirt. Win.
I too want one off these motors and have thought many times about putting one in my Galaxie.
ls1fiero wrote: Mine is the 3 + 1 trans. First gear for crawling only. I am guessing that it has a 4:10 rear but will find out. Have never actually measured fuel economy but estimate 10 MPG. Definitely a momentum vehicle that seems unkillable. I do love the thing. It just feels that it should have more oomph and better economy.
Now I want one again. My '94 F150 with the 5-speed got around 15-17 mpg on average. My "commute" was only 6 miles and it was 90% in town, stop and go. With 265 lb/ft @ 2,000 rpm and 145 hp @ 3,400 rpm it was definitely not a powerhouse but it was a smooth, low-rev driver. Revving it beyond 3,500 rpms only resulted in more noise and wasted gas.
Trans_Maro wrote: Most carburetor problems are ignition related.
lulz
Could use triple Weber DCOE ($$$).
Or for grins, triple SU HS4 or HS6.
It's a Ford, so loads of off the shelf EFI stuff would be a natural fit, either with a single plenum and throttle body, or triple, even hex ITB.
Manifolds would be cake to make, flat flanges with tubes welded on.
EDIS ignition, with either EEC-IV or Megasquirt running the show.
Or put a $40.00 carb kit in it and get it back on the road...
Rough idle and terrible fuel economy can easily be the engine in need of a tune-up.
When was your last tune up?
Is your vacuum advance working?
How are the plug wires?
How do the plugs look? If you're getting E36 M3ty mileage, you're probably running rich. Checking plugs will tell you this.
Where is your timing set?
Why not do a little diagnostic work before you go spin the "wheel-o-parts" and start throwing money at it.
I know the GRM collective is terrified at the thought of using a carburetor but on this extremely efficient engine design, adding EFI won't really make a huge difference for the dollars spent.
The understand what you got and tune it up approach makes good sense to me. Pulling plugs tomorrow.
This is more of a thread-jack then useful input, but I love the Ford 300ci I6. I've often wondered what it would take to turbo one of the EFI versions .
I know its been done with blow through carbs on the earlier 300s, but I've never seen it on the later EFI engines.
I had a bone stock 86 F 150 4X4 with the 300 and a 4 speed manual. Great truck. I modify almost everything but I left it stock. I'd follow Trans_maro's advice and just get it running right and enjoy it.
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