I Done Did Screw Up My Dauntless Carburetor

To make a long story short, when I first assembled and started to run my rebuilt Dauntless, it had a stmble at low RPM on tip in. Kinda like a bog. I went back and reviewed the carb rebuild and found the float level was a tad low - which I corrected. It only helped a little.

I started corresponding with a Rochester 2G guru and he suggested that since I had a cam (Crower torque grind for the Dauntless through T/A Performance) that I was probably not getting enough fuel when the transition ports started to become exposed. He advised me to take out the cluster and open up the holes in the idle tubes in the cluster by .005". I did this and it made things quite a bit better, but not perfect. I then opened them up another .003" and the issue was essentially gone. But......

So this past weekend I had an issue with no start/rough running that started suddenly. It seemed to go away after I cleaned the points but came right back. The Jeep seemed to have spark, so I went and concentrated on fuel. Upon taking the top off the carb, I found two things... The float level was still not right and the accelerator pump piston seal was swollen and was coming off it's stem. So, I replaced the accelerator pump piston and raised the float level. But, this didn't fix the no start issue. Skipping a bunch of troubleshooting - it was a bad condenser. And the true root cause for the bog was found - fuel level too low for the accelerator pump piston to move any fuel at light throttle. For sure it's fixed now and it is. The Jeep runs better than ever now that it's getting the squirt of fuel it needs. At this point the Jeep was running OK but I needed to set the idle speed and mixture. Here's where my current conundrum comes... The Jeep idles best with the idle mixture screws tuned all the way in! And it wants to be leaner still. To me, this means I never should've drilled out the idle tubes to get transient fuel when it was an accelerator pump issue the whole time. Since I can't undrill the holes, nor get replacement idle tubes (not even sure they can be removed from the cluster), nor buy a new cluster, I'm at a tipping point. I certainly don't want to lower the float level again sin ce the Jeep runs so well.

My only option (unless one of you kind readers has a 2G cluster kicking around they'd want to sell me or maybe even a NG 2G carburetor) is to open up the idle air bleed holes which I think will lean it out again and possibly compensate for having opened up the idle tube holes. Another thought I had was to silver solder the idle tube holes closed and redrill them to be the proper diameter, but I am not 100% sure of the right diameter, and I run the risk of destroying the idle tubes, so that option is out for now.

What do you all think?

John

 

Rebuilt Carburetors | Guaranteed Carburetors

my go to for all things carburetor..

 

Post a WTB, you never know. Even if someone has a carb with a worn throttle plate or stripped inlet it would have the part you need.

The majority of carb problems are ignition related...

 

The idle tubes or cluster are not available anywhere I've checked. So the heck with it, once I saw how they were made and how they could be removed, I used machinist skills and fabricated two new ones from 1/8 brass rod. Turned to .093 diameter OD, cut to 1.043" long, drilled .052 1.00" deep ID, then drilled .025" ID to meet .052" bore from the other end the remaing .043". Then the end with the .025" hole OD cut back .093" from the end to .062" diameter.

.025 is one hell of a tiny hole! Anyhow, I installed them, set the idle mixture which now doesn't require the screws turned all the way in (about 1.5 turns out now.) The Jeep runs really really good! In fact it 's never run this good. No bog, very snappy throttle response, idles dead smooth at 625 RPM (except for the odd-fire vibration).

John

 

Small bore 2g's are very common. It shouldn't be hard to come up with a few cores.

 

My 2g has the same bog on acceleration. Tell me more how you figured out the correct height for the float. Perhaps that's my carb's problem too.

 

Keep increasing the float level until you see the accelerator pump squirt with a small throttle opening.. That's what fixed it for me. No squirt on tip in for light throttle. Also raising the float level will give you more volume in what the accelerator pump puts out, also helping tip in bog for deeper throttle tip in.

If you can't get a light throttle squirt if you have to set the float higher than you're comfortable with, you can bend the accel pump linkage rod to low the height of the accel pump plunger in its bore. But, only a little bit. Going too much results in binding when the accelerator pump crank arm (the thing the linkage rod connects to) bottoms out on the carb body (a little tab.)

Also, adding timing advance helps with bog. I run my Dauntless with 93 octane and have the timing set at 13 deg BTDC. No pinging.

I'm very happy with how my Dauntless runs right now. It has NEVER run this good since I first drove it in 1984.

Let us know how you make out and whether timing/float level fixes your issue.

Cheers,
John

 

Your suggestion worked! Setting the float height solved my bog problem hesitation. The problem was finding the correct float height. The rebuild kit comes with a sheet of 3 pages of small print settings for hundreds of different 2G's. I used the metal tag to narrow down the application, picked a float height, and that seemed to do the trick. My wife and I took our '70 CJ5 out tonight and the bog at starting in first and at each shift was gone.