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Hi everyone, and I appreciate any advice in advance.

Have a '67, when I bought it we discovered someone had installed a carb for a 455 engine on it. I bought a brand new "4MV" carb. When received we took it apart, everything looked new, verified jets were proper and reassembled.

The reason we discovered the original carb was the wrong one was because it was running very rich. Now with the proper new carb, it is running even richer. I mean so rich that people get mad at me sitting behind me at a light, so rich I won't let my kids get near it while running. You get the picture.

We did the following troubleshooting:

- Verified all cylinders are firing.
- Checked vacuum, the engine is pulling 12-16 pounds, which is normal.
- Checked the timing, timing is correct.
- Plugs, wires and other ignition components are new and look good.
- Checked around the carb and gasket to ensure something isn't loose and drawing in air...nothing found.

We followed directions found online to calibrate the idle fuel/air ratio using the screws on the front of the carb, but this seems to have no effect at all. It seems like the carb isn't running on the "idle circuit."

We are completely baffled at this point. Has anyone been through this/have any ideas?

Thanks everyone for any help anyone might suggest.

Roy T

Contact Sparky... He's the expert in this arena and a Toronado nut! His contact info is on his site:
http://www.sparkyscarbs.com/

My $.02... Check the fuel well plugs on the bottom of the carb, if 67 had them and if you haven't checked already. This is a very common place to have issues. It just leaks into the intake, causing a very rich condition. Most people JB weld them, and it's reliable if done correctly.

rt_toro_67 wrote:Hi everyone, and I appreciate any advice in advance.

Have a '67, when I bought it we discovered someone had installed a carb for a 455 engine on it. I bought a brand new "4MV" carb. When received we took it apart, everything looked new, verified jets were proper and reassembled.

The reason we discovered the original carb was the wrong one was because it was running very rich. Now with the proper new carb, it is running even richer. I mean so rich that people get mad at me sitting behind me at a light, so rich I won't let my kids get near it while running. You get the picture.

We followed directions found online to calibrate the idle fuel/air ratio using the screws on the front of the carb, but this seems to have no effect at all. It seems like the carb isn't running on the "idle circuit."
Roy T

Could check, fuel pressure coming in, and that the float is really limiting the level.
Bruce Roe

Bruce and Mike,

Thank you for the advice! Sorry for the late reply, I was completely away from electronics for almost a week. Which really isn't a bad thing.

Thanks again, we'll take a look at these things.

Roy T

HOW do you know it's rich and not lean?

When a vehicle has a stinky, eye-burning exhaust stench, the usual problem is that the mixture is so lean that the engine misfires.

12--16 inches of vacuum is not "normal"; it's low, unless you're measuring it in-gear.

"Brand new" Q-Jet carburetors haven't been available except as dusty-box items for years and years. Is this a brand-new REBUILT carb? One of the left-over Edelbrock units? Something found on a shelf somewhere that'd been lost for twenty or thirty years? What is the carb number?

Schurkey-thank you for your response and sorry for the delay. I'm willing to look into any possibility. My apologies for calling the carb "brand new". It was rebuilt but done nicely. I bought it from the guy that calls himself "Rocket Scientist" from Lansing, MI. It is a model number 7027131 and my mechanic is highly confident it is the right carb with the right jets.

I will have to double check, but my I'm pretty sure my shop manual for the car states that the vacuum we measured was in the OK range.

So this gives us something else to consider, if it is running extremely lean. I have some things to go by if it is running rich (starting with the fuel plugs on the bottom of the carb as pointed out by another helpful poster), now to try to figure out remedies if it could be running lean.

I will share your thoughts with my mechanic friend and see if I missed anything.

THANK YOU!!

7027131 is the correct carb for a '67 that doesn't have CCC or any other emission option. Other than the excellent well-plug advice, verify your idle mixture screws are set at 1.5 turns out each. They wouldn't be enough to cause the REALLY rich issue but one more thing to check. Good luck.