I have a small Holley 2 bbl on my Bronco II.The way I jetted it was I hooked a voltmeter to the stock oxygen sensor since I wasn't using it anymore anyway.Oxygen sensors generate their own voltage once they warm up and produce about 0.5v when the mixture is at 14.7 to 1,lower than 0.5v is lean and higher is rich.All you have to do is hook the voltmeter positive to the wire from the sensor and ground the negative and use a range around 1-2v.Drive around at about 3000 rpm and the carb will be running on the jets and out of the idle circuits and you can get a pretty good idea if it is rich or lean.Realistically you are doing OK if you get a reading in the 0.5-0.7 range.

 

is running now. i had the crank ground and new bearings in, changed freeze plugs. that carb is working fine. the fuel mixture is good but I am only getting 12 MPG. any sugestions

 

I'm not saying there is going to, or was going to be a problem with that size carb on a 2.8. I think it would be fine. but what I am addressing here is the suggestion that you must downsize the jets. If you say or think this, you don't understand how a carburetor works. IF a carb is too large for an engine, that means the air flow going through it will NOT be sufficient to cause the vacuum needed in the venturi. Thus, fuel delievery will be a problem. In other words, the correct amount of fuel will not come out. Sizing the jets smaller, will only add to this problem. For a carb to be matched correctly, the proper amount of air is being drawn through the venturi. This allows a strong vacuum signal to be present and draw fuel from the nozzle. The jets allow proper metering of the fuel present in the nozzle. Decrease the amount of fuel in the nozzle, then give it a weal vacuum signal and you have a bad situation. Everyone thinks making jets smaller when a carb is too large is the answer, when actually you are making it worse.

 

i have one that came off a 85 B2. it was runnin and driving


anyone need it

 

Check to make sure the choke isn't sticking (partially closed) and check / set your idle mix and idle speed (I know you've probably already done it, but...). May want to also check your timing and the usual tune-up stuff. When was the last time all the filters were replaced? May also want to consider looking at your valvetrain, the 2.8s and earlier V-6s with solid lifters tend to be a little quirky and require adjustment every so often. Also depends on your driving style. I used to get 12-15 mpg (mixed city and hwy driving) out of a 351C with a C-4 automatic that was transplanted into a '67 F-100 when I tried real hard - after doing a complete rebuild on the carb, including replacing all the jets as well as rebuilding the sloppy a** distributor that had loose bushings and other worn out parts. I never got that thing out on enough open roads to really get a better idea on what kind of mpgs I could get out of it.

 

thanks I've done all that and now get 15 mpg.I am happier now

 

If you want to get the most out of your set up you need to dump the EEC, get the Dura-spark box and vac. advance dist. to go with. You will get more power and mpg, my 84 Ranger 4x4 2.8 V6 gets 16 city/22hwy. and pulls a 16ft boat pretty easy with a 5spd,31s and 3.73 gears, the only difference is my carb is a 2100 motorcraft 1.08 269cfm off a 70 302.

 

I`m planning on putting a 1.21 2150 on my `84 2.8 B2. I know it`s a lil too big but the price was right (free) and it flow the same as a holley 350. Duraspark is also on the way.

 

Full volumetric efficiency of a stock 2.8 is only 270 cfm @ WOT, if you want to use a larger carb than that, you need to have a,cam, porting and headers to be able to stuff that much more air thru it and take advantage of the extra capability. You CAN do it but you wont be gaining anything unless you can fully utilize it.

 

I`m just using it because it was free, and in really good shape. I am bolting on a set of edelbrock headers though.

 

how much?how much?

 

who much are you askin for that carb?

 

junked it