Engine running extremely rich

[dan2286]

My Cutlass is running extremely rich. I am assuming the problem is mainly at idle, since the brand new plugs are fouled out after less than a mile of driving. I think I have went through about half a tank for the 3 miles total I have driven this car since I got it running. Most of the time is has been running, it was sitting. It has done this with 2 carbs.

First time was the Q-jet that came on the engine. I could definitely tell it needed rebuilt because of the fuel seeping out of the accelerator pump shaft and other parts of the carb. Not sure how the choke was working on that.

The second carb is a newer Holley 600 cfm with electric choke. This carb was sitting for about a year and still had some old fuel in it from when I took it off. It really had barely any use on it before this. Choke seems to work fine, but I don't know much about carbs, so I can't be sure. After a couple minutes of running, the choke plate would be fully open and idle would drop down like it should. As far as I know, this carb has some type of check valve or something to protect the power valve, so I don't know if it could be bad.

I am assuming the problem is in the carb, but I am not sure what to look for. I am thinking it is not ignition related since the car ran great when I put a new set of plugs in, but ran worse as they got more fouled. Any suggestions?

 

[megaladon6]

have you retuned the carb or checked the float level?

 

[dan2286]

have you retuned the carb or checked the float level?

I tried tuning it, but it did not seem to be affected by turning the mixture screws. That was with the engine warmed up and with the choke open. It has the non adjustable float, so I guess it has to come apart to check that.

 

[monte olrac]

Alsocheck your fuel pressure, if it's too high it will force fuel past the floats. I had that problem when I put on an aftermarket mechanical fuel pump

 

[dan2286]

Alsocheck your fuel pressure, if it's too high it will force fuel past the floats. I had that problem when I put on an aftermarket mechanical fuel pump

I don't have a gauge for that. I wasn't even considering that though because the pump is a stock style replacement and pretty old. I would think if I did have problems with it, there would be low or no pressure.

 

[RegalBegal]

Sounds like you have two carbs that are in need of a rebuild. The Holley may have a stuck or bad float. Even though it had little use, just sitting with old gas can muck up the works. I'd say rebuild the Q-Jet and toss the Holley especially if this will be a street car. You'll get better mileage, and it will behave better at part throttle. Holleys aren't a bad carb but they work better at WOT.

 

[dan2286]

Sounds like you have two carbs that are in need of a rebuild. The Holley may have a stuck or bad float. Even though it had little use, just sitting with old gas can muck up the works. I'd say rebuild the Q-Jet and toss the Holley especially if this will be a street car. You'll get better mileage, and it will behave better at part throttle. Holleys aren't a bad carb but they work better at WOT.

That was pretty much what I was thinking. I was hoping I could get by with the Holley till I could rebuild the Q-jet, but I guess I was wrong. I know what you are saying about using the Q-jet, I just had the Holley to use as a spare. I have 3 Q-jet cores and I have to kinda take parts from all three so I can have all the needed "options", I guess I could say. I think I have been avoiding having to take apart 3 of them.

 

[RegalBegal]

I think I have been avoiding having to take apart 3 of them.

Don't let the Q-Jet intimidate you. There is plenty of info about them on the web. Yeah, I know it can be a b*tch to dial them in but, it's well worth it. The two best things you can do when rebuilding are 1) re-bush the throttle shafts and 2) seal the well plugs with some JB Weld so they don't leak.

Here's a few links to help you out.

http://www.carburetor.ca/
http://www.florida4x4.com/tech/quadrajet/500cid.com/Quad.htm
http://www.carburetion.com/quadrajet.asp
http://corvette.wikia.com/index.php?title=Intake Here look for Lars' Quadrajet tuning paper.

 

[dan2286]

I think I have been avoiding having to take apart 3 of them.

Don't let the Q-Jet intimidate you. There is plenty of info about them on the web. Yeah, I know it can be a b*tch to dial them in but, it's well worth it. The two best things you can do when rebuilding are 1) re-bush the throttle shafts and 2) seal the well plugs with some JB Weld so they don't leak.

Here's a few links to help you out.

http://www.carburetor.ca/
http://www.florida4x4.com/tech/quadrajet/500cid.com/Quad.htm
http://www.carburetion.com/quadrajet.asp
http://corvette.wikia.com/index.php?title=Intake Here look for Lars' Quadrajet tuning paper.

I have rebuilt one as practice and it wasn't that bad. I never used it though and it is covered in dust and probably needs another rebuild. It will be donating the base plate, I think it's called. The throttle shaft on it is actually still tight, so I plan on leaving it alone.

 

[dan2286]

I was planning on rebuilding a core I got off of ebay, but I got it apart and it looks like it got some water in it. It was also different looking inside, looked like a much different design than others. I can't even get the float out because parts are rusted inside.

I pulled apart the carb that came on my engine and it is much nicer inside. Looks like the well plugs were leaking, but that's an easy fix. Hopefully will be ready today or tomorrow.