I found the pair of Motorcraft jets, and they are 48's. That's probably why they are still around, being too small for even high altitude use.

Make sure the passages that carry fuel from the jets and the power valve into the main circut are not obstructed in any way.... with dirt, varnish, metal filings, teflon tape bits ...ect. That could cause it to lean out, bad.

 

Thanks! I have been drilling out my 54s a little at a time, I think Its getting better, also cleaned passages (it is professionally rebuilt, but you never know) I raised float level a bit too. Now all of the sudden it will not idle huffs, chuggs, rumbles, then dies.... Oh the joys of carboration!

 

So it's getting worse? Oh boy.

 

It runs better at speed and accelleration, however wont idle ... Did run ok, and idle for one or two days, then idle went bad on me.. I am checking componants one by one to see if something failed..

 

Most carbs have a temporary fuel feed called the "transfer slots". The idle circut is seperate from the main circut. Therefore, changes in jets..ect have minimal effect on the idle circut. Likewise, changes to the idle fuel mixture has no effect on the air/fuel mixture of the main circut. The main circut draws fuel through the small booster venturies located inside the primary venturies or throttle bores. With the throttle blades closed, this circut is out of operation. The idle circut allows vacum to draw fuel out of small holes located on the bottom of the carb, below the main venturies. As the throttle blades are opened, the air flow is now through the main venturies and the idle circut will cease to operate, but the vacum signal at the booster venturies may still not be enough to bring the main circut into operation fully, and the xcell pump shot is quickly used up. This is the job of the transfer slots to provide fuel during this period. This is the period were the job of providing fuel, is "transfered" from the idle circut to the main circut. The transfer slots are usually small retanglier slots located right at the edge of the throttle blades on the sides of the throttle bore. These are usually located were the throttle blades usually sit when it's idling. If the throttle blades are adjusted too closed, or too open, then the transfer slots won't work properly and the idle circut will be out of operation. If the throttle blades are too open then idle circut will be shut off, and the transfer slots won't provide enough fuel by themselves for idling. It sounds like that perhaps the idle circut isn't working at all and the engine is trying to live off the main circut alone.

 

Thank you for that explanation, I do believe it will help know just what is happening in there.

 

My guess is that the float level is too high and at idle you are flooding.

 

Hummmmm, I did raise it a bit.. And no matter where I set the idle mixture I would not idle well at all. Im having a look at that! Thanks!

 

holley jets and power valves will fit in the old motorcraft 2bbl carbs, I have a stock 302 that is running #50 mains. and with the bigger the number the bigger the jet size is.