fuel leak down

[megaladon6]

i'm having 2 problems with my carb that i hope y'all can help me with. the carb is a holley 4175, refurbished by holley.
first problem; i have the carb tuned correctly but the idle mixture screws are almost all the way in (leaned out). the engine does die if i turn the screws all the way in. the throttle valves are closed. can the floats cause this if they are too high?

next problem; not sure if it's a carb problem or not. if the car sits for a couple of days it takes awhile to get fuel pressure up. i'm using a mechanical fuel pump. there are no leaks.

any help is appreciated.

 

[pontiacgp]

the 4175 is a spread bore carb and it's a reverse idle carb..if it was rebuilt there should have been decals just above the idle bleed screws....in for rich and out to lean...I had that carb on my car for a while. I had to go up 3 sizes on the jets cause it would run out of fuel on the highway and my engine was a stock 305. The carb would run ok for a while and then run like crap. I had that carb apart more times than I want to remember. I hate to tell you but that carb is probably the worst carb holley ever made. If you just got it I'd try to take it back cause from what I have read that carb will never run right.

 

[megaladon6]

the car runs great at all rpms and loads. once i have money i'm going to EFI but till then i have to keep the carb.

 

[pontiacgp]

You said the carb is tuned correctly but you said the car dies if you have the idle screws all the way in. The car does not die with the bleeders all the way in. All your doing is shutting off the air bleed and richening up the idle mixture. Holley has a book on that carb, it may help you out.

 

[megaladon6]

i asked holley. they said the engine should die with the mixture screws all the way in and that in is lean, out is rich. this is held up by my spark plugs and basic air/fuel meter.

 

[pontiacgp]

you have it wrong..it's a reverse idle carb...in is rich, out is lean

4175

 

[megaladon6]

dude--i checked it with an air/fuel ratio meter. holley did say that there are 2 version of the carb, i think it was emission and non-emissions. one went in=rich, the other in=lean. anyway, when i turn the screws out alot i get blueish/black smoke out the exhaust and my spark plugs get fouled. when i turn the screws in it leans out the carb, trust me.

 

[pontiacgp]

then you don't have a 4175 carb...dude...whoever told you there is 2 versions of a 4175 doesn't know what they are talking about...did you even look at the link I looked up for you??

 

[84GP455]

In my opinion Holley carbs suck~
i've had them new,rebuilt,used,you name it and they all sucked~
i've had a double pumper catch fire! they constantly need tuning, i would tune them in the spring then by summer time, guess what? they need to be tuned again due to the climate change! All my problems ended when i got an Edelbrock 750 carb, man what a difference!! I've had the same carb on my car for 15 years,(they had just come out) and i've only had to rebuild it twice, due to the MTBE additive in the gas today it makes a white powder like residue in the carb. But as far as out of the box reliability you can't beat them!!

 

[megaladon6]

pontiacgcp: you need to pay more attention. i confirmed the in=lean with a digital air/fuel ratio meter. if i turn the screws out the exhaust blows unused fuel, therefore rich. the 4175 is the only holley carb with the same bolt pattern as the q-jet and that's what is on my car,plus somehow i think holley knows what their carbs are and how they work and holley told me that there are two version of the 4175. also, read your own link!!! page 53 center column starting at the bottom paragraph. pay particular attention to the use of the word SOME. yes, some as opposed to ALL. this means that there are SOME carbs withOUT the reverse idle adjustment.

anyway back to my original questions-i can't get a new carb because i have no money due to unforseen circumstances. so does anyone have an idea why these things are occuring?