I have a 67 Bronco with 289 in it - It is running a carter 4070 electric fuel pump with 5-7 psi. I can't do the mechanical fuel pump due to the serpentine belt conversion. It has a Holley Remanufactured carb that has 1 sticker that says 735969-0775 and then it has 9TK in the drivers side footing. It also has another number of 64-5334 on it. The jets in the carb are 56's and the d*mn thing is running extremely rich. I have the idle mixture screws about 1 1/4 out from being seated and it is pulling 17 on the vacumn gauge. Is there any way of finding out if the rest of the internals on the carb are the correct for my application? I do mainly street driving with an occasional trip to the mountains (fishing and camping - not crawling)

Any help would be appreciated.

thanks,
dan

I have NO DOUBT that your carburetor is running rich.
The carburetor you have is a 1969 1.23 venturi carb which flows appox 352 CFM WAY WAY TO MUCH FOR THAT 289 engine.
The ORIGINAL application for your carburetor is a 1969 Light Duty Truck (F-100/F-150) with the 360 FE big block engine.

NOT ONLY THAT but when the generic rebuider rebuilt it they installed richer jetting since your carb was supposes to ONLY have 54 jetting not the 56 that yours have.

By comparison a 1969 bronco (67 would have been very similiar) only had a 1.08 carb flowing only 287 CFM and had 48 jetting.

Two perfect lessons here:

NEVER, NEVER, EVER buy a rebuilt carb, instead rebuild yours and save money and get the job done right rather than increasing your problems and ending up with a "generic" carb that runs crappy on your particular application.

And ALSO IF YOU END UP WITH A REBUILDER MAKE SURE IT IS TOTALLY CORRECT FOR YOUR APPLICATION AND IT HAS BEEN REBUILT CORRECTLY NOT FULL OF CROSS MIXTURE OF PARTS JUST TOSSSED IN TOGETHER.

Sounds like its time to start over, fortunatley there are thousands of 1.08 venturi 2100's out there and they are not the expensive. If you are not looking for a numbers matching one you should have lots of options and a diverse price range depending upon what you want to do.

End the confusion replace your carb.

Good Luck,

Bill White
White Automotive

:o)
Your carb should have had 53 jetting not the 54 I said, and certianly not the 56's that are in it.

Bill White
White Automotive

I thought the 56's might be a bit big. I do have some 53's that I can throw in with a quick rebuild kit to make sure everything else is where it needs to be. I have also been playing with the timing to get it where it should be. Seems like 12 btdc is where it plays the best.

1. I doubt ANY 2bbl carb short of a holley 500 is too big for your engine.

2. I doubt the jets being 56's instead of 54's is going to make your engine run incredibly rich.

3. Is the choke opening all the way?

4. Is fuel dribbling down the throats?

I think a carb set up to run rich (and three jet sizes larger for a 2100 is running her rich) and a carb thats intended to feed a 360 FE Big block ford engine for a full size truck, will definetly cause it to run to rich for a 289 powered Bronco.

Not only that but my biggest concern (besides the oversize) in this case would be what other "modifications" have been done to this carb by the rebuilder. I see these "rebuilt" carbs all the time with mismatched jetting, wrong jetting, wrong bench settings, mismatched idle mixture screws, wrong accelerator pump settings, I have even seen one with the wrong butterflies installed.
Even without anything else wrong (and I am willing to bet it has at least been bench set incorrectly) the three jets sizes larger is already disrupting and throwing off the proper flow from this carb EVEN if it was on the correct vehicle.

The 289 is an EXTREMELY sensitive motor when it comes to overcarburetion due to its extremely small valves and tiny ports, and its fast revving stroke.

We have this debate every month or so, but it really comes down to physics, and those physics do not change. An engine is basically an air pump and can only pump a given amount of air through it based entirely on bore and stroke, times its maximum RPM and then factored (decreased) by its volumetric efficiency. The stock 2V 289 is truly not a very efficient VE engine, only about 65-70% efficient if that. And this engine is probably spun out at 5500 rpm.

He's running rich, the carb is the reason. Its bigger than what his engine needs. No brainer.

Remember we are not talking racing or high performance here. Put away the hot rod magazine,talking about larger is better, it isn't.
Replace the carb with the correct application and you will be way more happier. If he showed up at my shop I would not waste his money trying to make this mismatch work, I would replace the carb.

Bill White
White Automotive