66 273 4BBL Carb Help

[66FormulaS273]

I love this site, great people and I've learned a lot eading threads over the years. Hoping for a simple solution but after reading a few other carb threads probably not. I have the original 4122S carb on 273 Hipo C.A.P that has been rebuilt and bench tested. Engine has been rebuilt, and only thing that changed was bored 30 over. Engine just won't idle properly and eventually boggs down after a minute or two. Sent it back to the guy who rebuilt the carb and he opened the needles a hair to let more flow through and that didn't helped at all. In the process of trying to break in the cam my mechanic installed an Edlebrock 600cfm and it runs and sounds great. That was the reason for opening up the needles on the 4122S which is 500cfm. After spending $375 to have the carb rebuilt I'd really like to use it. I do have a 4305S carb that we can try but I'm looking for suggestions to try and make the original work first.

Thanks for any advice.

 

[pishta]

If it bogs and chokes/dies after 2 minutes, that sounds like floats. Either the needle/seat is not sealing or your fuel pump needs to be regulates down to about 3-5 psi. also check your floats for sinkers. Only other car I worked on that would act up after 2 minutes like clockwork was a fuel pressure/float issue, black pump into an Edelbrock with the regulator turned all the way open, 15 psi! I think the ballpark on a Carter/Edelbrock is invert the top and the floats should lay parallel with the top, but your spec will be called out in the rebuild literature.

 

[66FormulaS273]

Thanks for the advice Pishta. Saw previous comments you made in another thread on needle adjustment and bending the carb float for proper fuel consumption. Will see if this works or if it's the fuel pump.

 

[Sreyno]

Are you sure you don't have a plugged fuel filter? If you run the car for a few minutes and it bogs down it could be dirt is plugging the filter.After it sits for a while the dirt settles and it will run for a few minutes more then do the same thing again.