Hey guys looking for a cheap easy way to give my truck a little more power its a 78 F100 with 300 i6 1 bbl carter yfa carb. wondering if there are any carb mods i can do or anything anyone has done to give it more speed. i do realize that there is a limit to what i can do and it wont be very fast no matter what i do because its a 4800 lb truck and a 1 bbl carb. Any suggestions? Ideas?

 

The usual suggestions are a) EFI exhaust manifolds b) they require either a Y-pipe or equivalent (unless you want to run a true dual exhaust on a 6, which most people do not like) - the Walker number is 45166 but their production seems to be intermittent. c) A free-lowing muffler, the Walker is 2.5" so you would need a 2.5" inlet. d) Bigger exhaust, 2.25" to 2.5" is enough e) Better intake manifold - the usual are either from Clifford or Offenhauser - note with the Offy you will need to figure out a way to heat the manifold, the normal way is to run hot water from a heater hose through a fitting and plate on the bottom of the manifold. f) Carb of your choice. 4-barrels in the 450-600cfm range are usually recommended. g) Easiest next step is rocker arms from a Chevy 250, will increase lift to 1.75 (increase from Ford stock) to simulate a mild cam.

Next you get to true mods... replace the cam etc. Read The Frenchtown Flyer's posts if you really want to get into engine mods, he is cited as "the guy" for that. Read the stickies at the top of the forum, especially the one on why you need to heat the intake. And then start doing searches in the forums (top of the page on the right; if you go to Advanced Search you can restrict the answers to year and forum so you can narrow it down.) There are only a coupla thousand posts asking these same questions.

 

i looked into better carbs and such but wondering if there is any way i can keep my original carb and change squirter size possibly? also i have changed to a bigger exhaust pipe size but not changed the manifold size. i prefer the single exhaust personally and have a flowmaster super 50.

 

Just depends on what kind of money you want to throw at it. Dual manifolds are cheap, Y pipe maybe $50, but when you get on the intake side you are looking at several hundred dollars. But you are only looking at incremental improvement until then, I believe.

 

okay sounds like can do an exhaust manifold any brand better than another?

 

Ford. The EFI manifolds are almost a drop-in fit, work 'way better than the log manifold (based on mine probably better than many headers) and can be had on line for under $100. Try getting headers at that price.

 

thank for assistance!

 

The dual manifolds are still a single exhaust. The pipe afterward is a Y that brings them together.

As for the carb, you don't tune a carburetor for more power, you can only tune it to work with your engine. So if it already drives well (no stumbles, bogs, hesitations, etc), gets decent mileage, your spark plugs are a healthy tan, there's nothing more you can do to the carb. Putting more gas through it will just make it run worse.

The only way to increase power through a carburetor is to increase its CFM (Cubic Feet of air per Minute) and that can't be done without changing carburetors. Then, opening up the intake/exhaust so that the engine can pull that extra air/fuel in through the carb, and get the exhaust out the back.


Fortunately, the 300 is extremely under-carb'd from the factory and has a very restrictive intake/exhaust, so it's easy to open up. Get some EFI exhaust manifolds from eBay or a junk yard, install them, have the two exhaust outlets worked into your current exhaust, and then get a Clifford or Offenhuaser intake manifold and a nice 2bbl or 4bbl carburetor, and you'll be amazed what your 300 will do.

There are LOTS of posts on here about getting more power out of the 300. Do some searches and you'll find much more information than we can give you here. If you have any specific questions, definitely ask!

 

Turn the carb metering rod adjustment screw (internal) 1/4 turn clockwise.

 

where is that located, bowl?

 

found it, what will that increase/decrease?

 

It will enrich the part throttle cruise A/F ratio a tad. Engines of that era were jetted lean to pass emissions.

 

okay any other internal adjustments needed to compensate for that adjustmant

 

Not really. Set idle mixture screw but that shouldn't change much.

 

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