Hi all-
It's been a while since I've posted, but always finding good bits of info on here. Hopefully I'm posting in the right section...having fuel system issues with my 52 and have isolated it to my carb. There's a new tank, sending unit, lines are good, fuel pump is good, but I can't keep it running/idiling. After rebuilding the carb to the best of my ability, fuel is coming from a hole between the primary's venturis/tubes (pic included) on acceleration/when the throttle linkage is actuated. Is the float level off and creating a flooded situation? Bad gasket? Am i missing a check (ball) valve? (Idk, am I? Some self-depracating humor to combat the frustration)...I apologize for any inaccuracies in explaining parts and the symptoms, but I've rebuilt the carb years ago and have never seen fuel 'weep' out of that center hole and am thinking that has something to do with it not running, or more specifically even staying running/idiling. I attached a few pics and thank you in advance for considering helping me. The carbs been off and on now 4 or more times, but I'm just stubborn enough to not take it to someone.

 

I'm not an expert on carburetors, I've rebuilt a fair number and I can hold my own on rebuilding & some of the considerations of troubleshooting them; but, my first inclination is the float - a guess from the hip at this point.

It would certainly help if you could identify the model number of the carburetor.

Here's a link you might look at to get an overview which may assist. It appears somewhat similar to your situation, again, the model number would help as others may have far more information especially as it relates to the particular model number of the carburetor.

https://cliffshighperformance.com/si...p?topic=2228.0

 

Norm-
Thank you for the quick reply...the carb is a Rochester 4 Jet RP. Is there more info I could get off the carb? I will take a look at that link. So if the float level is off (not low enough it will create a flooded state, the car won't run and excess fuel may come out that center hole in the primary cluster assembly?
-Jeff

 

Thanks for that carburetor number. Honestly, I am clueless on that carburetor. I have never even seen one I don't believe (maybe I have but never knew it). Read the link I provided first to see if it addresses your situation.

Did you change the floats when you did the rebuild & did you check the levels on the floats during the rebuild? Did this condition slowly develop over time (was it sitting a long time without running) or did it develop after a most recent rebuild?

 

I did not change the floats when rebuilding it. One float was sticking. The needle and seat weren't sitting right, but fixed that (cleared debris I'm thinking) so the float could freely move and the needle would seat properly. Then I adjusted them. They were fine months ago and I think it developed after the rebuild/or I messed them up during. I did look at the service manual to confirm float levels and thought I was close.
Thank you.

 

It sounds like the floats to me or a mouse turd under the needle. If its not a float, it could be the configuration of the metal which supports (holds) the floats which would mean to remove the carb and examine in detail. The other area I can think of which may be a far push is the notion/idea of an A/F mixture screw seriously out of adjustment or even having fallen off the carburetor. I think that's pushing the limits but I'm not looking at the carb.

 

Give this guy a call, I think his name is Mike at:

https://daytonaparts.com/universal-r...arburetor.html

 

The hole could be a vacuum break to prevent pullover from the accelerator pump circuit. There may be a check ball in there or the shooter nozzles may be clogged and fuel is backing up when the throttle is moved. An exploded view of the accelerator pump circuit would help.

 

Ok, I was thinking I'll have to take the carb apart and look at the floats, but then I saw one of the idle screws (pic attached) the tip broke off. Could that missing screw tip be the sole cause of it not being able to maintain running/idling?

 

Thank you therobski, I will call him.
-Jeff

 

Thank you for replying shiftbyear, The nozzles are clear, but maybe the check ball is missing. I think the accelerator pump is good, but does it even come into play when the car is just idling? I can't get her to stay idling.

 

Norm-
You may be right about the idle screw...I thought I replied directly to your last post...I did reply with some pics and info about a broken idle screw.
Thank you!
-Jeff

 

Jeff - Sorry, been playing golf all day then picking persimmons. Absolutely, the A/F mixture screw tip could be the culprit. Sorry I didn't see your earlier post.

 

I appreciate the reply, Norm. I will get a new screw and hopefully that does it. Would that broken screw somehow cause fuel to come out of that hole/plug in between the primary's nozzles? The nozzles are clean and squirt fuel, but that hole in between is weeping fuel when actuating the throttle.

 

Jeff - I don't know that carburetor well enough to suggest an answer.

Loosening the screw strengthens the air fuel mixture increasing the amount of fuel to the engine; and, tightening the screw weakens the air fuel mixture decreasing the amount of fuel to the engine. With the tip of the screw broken off, I would assume its causing more fuel to enter the carburetor. Is it emanating from that hole? I can't say - I don't know that carburetor. Is that hole an idle air bleed? I don't know. Let's say it is, if it is and there's fuel coming from it, then I'm suspecting you're feeding too much fuel and the fuel is escaping through that hole? Honestly, I'm shooting from the hip.

 

Thank you, Norm. That totally makes sense considering the flooded situation. I'll look at some diagrams again and see if I can figure out what that hole is.

 

Jeff - Have a look at these diagrams. I was primarily concerned with addressing what I suspected might be the idle air bleed (referred to as the top bleed I believe) in the 1st image - I think this may be correct & I believe with the tip broken off the idle screw what you're witnessing is fuel flow through the idle air (top) bleed hole. If its feeding too much fuel, it's doubtful the idle tube is able to meter fuel correctly (which is the purpose of the idle tube) and it's continuing to exit via the top bleed. I'll provide the link below. Have a read of the Operation of Idle Systems.

https://www.hometownbuick.com/1957-b...el-carburetor/

 

According to the Doug Roe carburetor book, there should be a check ball under that.

 

Norm-
It really gives perspective seeing the carb diagram from the side view. I'll take a look at that link and thank you again! I ordered a kit from Carb King today, and if it's only the idle mixture screw then I have a kit on standby.
-Jeff

 

Would there also be a small 1/8" lil' rod pinged into that passage to hold the check ball in?