Rochester 2 Jet Question

[SonOfThomp]

Is this carb 'junk'? I plan to eventually go with a QJet, but for now, I am putting money elsewhere. It's running pretty rich, with black carbon spurting onto the pavement when it starts. MPG is about 15 in mixed driving (this is a 1961 Bel Air with a 350 and 3pseed O/D), although I am still experimenting with the use of the O/D.

Tips and suggestions welcome!

SoT

 

[blumun53]

No, these carbs are not typically "junk"---however---in your case, it sounds like there may either be a metering rod problem, or it's just out of adjustment. These aren't performance carbs, so usually they do OK on fuel usage. A good, repeat good, quadrajet will do pretty good on fuel AND performance if set up and used properly. You mention that it spurts black stuff when started up. That's probably because it's leaking down while setting idle for a long time without being started. Sounds like a metering rod issue. This is most likely because one of the two (maybe both) is not seated properly inside the float bowl. It could be that they aren't set properly in the round brass apparatus. Or, it coud be that the thing is simply worn out. It would take inspection to determine the real cause. These carbs are pretty simple, and doesn't take a lot to repair them. Good luck and I hope this helped.

 

[1958 delivery]

No, these carbs are not typically "junk"---however---in your case, it sounds like there may either be a metering rod problem, or it's just out of adjustment. These aren't performance carbs, so usually they do OK on fuel usage. A good, repeat good, quadrajet will do pretty good on fuel AND performance if set up and used properly. You mention that it spurts black stuff when started up. That's probably because it's leaking down while setting idle for a long time without being started. Sounds like a metering rod issue. This is most likely because one of the two (maybe both) is not seated properly inside the float bowl. It could be that they aren't set properly in the round brass apparatus. Or, it coud be that the thing is simply worn out. It would take inspection to determine the real cause. These carbs are pretty simple, and doesn't take a lot to repair them. Good luck and I hope this helped.

A Rochester 2 jet has metering rods????????
He's having this problem with a 2 jet, not a Q-jet.

 

[skipxt4]

Rochester Carb**

SoT; You get 15 mpg with a 350 engine. If its blowing black smoke out the tailpipe, its either a choke issue. (choke staying on or not adjusted correctly) or like Bluemun stated. ( carb is loading up with too much fuel) The float adjustment is probably off. The carb probably needs a rebuild kit. Also make sure you're using the correct base gasket, for the carb, and intake that you have. I've seen people use the wrong gasket, and cover up passages that should be open. And, Roch. 2 bbl. carbs don't have metering rods. The 4 bbl. carbs do. Buy the kit, and do it. They are very easy. Skip

 

[tripowerguy]

Take the carb apart and check that the powerjet plunger is functioning. If it is stuck open it will pour fuel into the intake.Vacumn holds the plunger off and when you floor the throttle the lack of vacumn causes the spring to push the plunger down and open the powerjet. If a carb sits for a long time the spring holds it open without the engine running and it stays open due to varnishes ,etc. When you take the top off turn it upside down and work the plunger several times while spraying it with WD-40. Needle and seat and powerjet plunger is the most common reason for a Rochester 2 jet to run rich. They are to simple of a carb to have that much go wrong. Also make sure that the choke is pulling completely off. The choke should be fully open when the engine is up to temperature. Roy

 

[SonOfThomp]

I love this site; you guys are great!

Mnay Thanks
SoT

P.S. I take it that 15 mpg in town, with a 350, isn't gonna get any better even with carb work - hence the "applause" I got from skipxt4?

 

[blumun53]

A Rochester 2 jet has metering rods????????
He's having this problem with a 2 jet, not a Q-jet.

Oops, my bad, on the 2-jet--q-jet thing. I had been up a very long time when I responded to this earlier. (That's my story, and I'm stickin' to it!) Either the plunger is not functioning properly, or a choke adjustment are the first places to look. Performance would be enhanced by a 'good' quadrajet, but if you need the 2bbl to work for now, it should be a fairly easy fix.