What are symptoms for Riviera running to rich?

[Deadpurpledog]

Recently replaced carb and don’t believe mechanic was very familiar with them.  Symptoms I’m experiencing include: gasoline smell, hesitation when punched & occasional miss(recently tuned).  May I have your thoughts, please?

[Pfeil]

Running Rich = high C0 and black smoke. Black sooty spark plugs.

[avgwarhawk]

Poor gas mileage. Gassy smell. 

[Xander Wildeisen]

Fuel pump?

[gungeey]

Stick your finger in the tailpipes and check for soot, proctologist style. 😆

[joe_padavano]

[edinmass]

Replaced a carb……..odds of it being correct are probably less than ten percent. Rebuild your original, and all will be well. When carbs get replaced they tend to get “over carbureted” IE people almost always install larger cfm units.

[EmTee]

Do you see any gasoline stains on the intake manifold around the carburetor?  There is a welsh plug on the front of the carburetor body near the fuel inlet that can leak gasoline.  I carefully re-seated the one on my Riviera when it began to leak and applied a bead of epoxy (e.g., JB Weld) around the circumference.

[joe_padavano]

1 minute ago, edinmass said:

Replaced a carb……..odds of it being correct are probably less than ten percent. Rebuild your original, and all will be well. When carbs get replaced they tend to get “over carbureted” IE people almost always install larger cfm units.

^^^THIS. "Replaced carb" with what? A correct, identical replacement? A generic rebuilder Frankencarb? An aftermarket Edelbrock that's calibrated for a 350 Chevy? Hard to help without more info.

[Deadpurpledog]

“Original” carb had hole in front.  Tried high temp epoxy which did not work.  Mechanic ordered replacement.

[Deadpurpledog]

Tried EmTee and epoxy didn’t hold.

[Deadpurpledog]

There is “soot”.  When I start it up, both exhausts create a black circle.  Guess the good news is that compression must be ok!

[joe_padavano]

37 minutes ago, Deadpurpledog said:

“Original” carb had hole in front.  Tried high temp epoxy which did not work.  Mechanic ordered replacement.

First, what year Riv? Second, what "replacement"? If this is a rebuilder carb, be sure it is actually correct for your particular application. Most are not as they are one-size-fits-many calibrations. GM had specific carb numbers and calibrations for every year and engine combo. They typically are not the same from year-to-year.

[EmTee]

Has anyone checked choke operation?

[Deadpurpledog]

Don’t know.  Am going to carb shop Monday.  More “news at 11”.

[carbking]

Why did the original carb have a hole in front?

 

What was supposed to be connected here?

 

Jon

[EmTee]

I think he's referring to the plug that leaks on the original carb.  Rochester came up with a 'Rube Goldberg' bracket w/ setscrew to try to hold it in...

 

 

Edited November 20, 2023 by EmTee (see edit history)

[Deadpurpledog]

Thanks EmTee.  I have no idea, CarbKing.  All I know is that it was leaking gas and it was instantly vaporizing on the engine.  How can anyone know on a 55 year old car if it has the original/correct carb unless they purchased it new?

[John348]

7 hours ago, Deadpurpledog said:

  How can anyone know on a 55 year old car if it has the original/correct carb unless they purchased it new?

Many of here know what the original carb should be. Send a picture of the carb that is on your car and see what info you get back.

[joe_padavano]

7 hours ago, Deadpurpledog said:

Thanks EmTee.  I have no idea, CarbKing.  All I know is that it was leaking gas and it was instantly vaporizing on the engine.  How can anyone know on a 55 year old car if it has the original/correct carb unless they purchased it new?

Every single carb that GM used had a unique identifier number stamped on it. With very, very few exceptions, GM used a specific carb calibration for every application and every model year. Rebuilders cannot practically stock that large a variety, so at best they stock carbs with compromise calibrations that are supposedly good enough to be used on multiple years and models. If GM thought one calibration could be used across that many applications, they would have done it to save inventory cost.

 

In the case of your 1967 Quadrajet, the original carb had a round stamped tag imbedded in the driver's side of the carb at the front. This tag  had the carb number on it.

 

 

 

[Dandy Dave]

All the advice above is why I chose to rebuild an original carburetor than to use some aftermarket thing even if I have to do some machining to put it right. There's a ton of after market crap advertised everywhere on the net. The first red flag is no adjustment screws where the original had them.   

[joe_padavano]

I should add that the correctly calibrated OEM carb for a 1967 Riv with 430 would be Qjet number 7027240.

[carbking]

Purple dog - the reason I asked which hole is that I have seen folks do funny things about removing, disabling various functions. There are a couple of vacuum ports in front that might have been open.

 

EmTee did post the Rube Goldberg fix for a leaking front access plug (the big hole in front), which seldom worked. But it is possible to remove the plug, thread the hole, and insert a threaded headless plug with blue Loctite, and it will NOT leak. Just wasn't as easy a "fix" for the legions of GM mechanics that needed easy fixes on these units.

 

Count me in the group that are saying fix what you have, if you have the original. Hopefully, the original was not traded in as a core. If you have the original 1967 7027240, feel free to call during normal telephone hours, and I will be happy to suggest issues to look for on the 1967 carbs.

 

Pre-1968 Q-Jets can be somewhat challenging, but generally they are not impossible. Once it is done, it should easily last another 1000,000 miles.

 

Jon

[JACK M]

I don't want to hijack so will start my own thread about this subject.

 

[60FlatTop]

1 hour ago, carbking said:

Pre-1968 Q-Jets can be somewhat challenging, but generally they are not impossible.

I live 20 miles from the Rochester Products plant. Back in the late 1960s a friend of mine had  post production quality control job there. That was all I needed for confidence. If he could do it I sure could.

 

And I did.

[Laughing Coyote]

Here's one on my local CL. 

https://tucson.craigslist.org/pts/d/tucson-67-riviera-quadrajet/7684735350.html

[carbking]

The carb pictured above looks nice in the picture, but if it were truly restored, as advertised, it would have a red identification tag on the pump side of the carburetor.

 

Jon

[joe_padavano]

36 minutes ago, Laughing Coyote said:

Here's one on my local CL. 

https://tucson.craigslist.org/pts/d/tucson-67-riviera-quadrajet/7684735350.html

I realize this may be difficult to believe, but not every seller on the interwebs is knowledgeable about the item they are selling. That isn't even close to the correct carb for a 1967 Riv. That's a mid-to-late-70s Qjet. The seller cleverly doesn't show the stamped carb number on the side. I'd believe that's a 1977 Riv carb, possibly with the Olds 403, as that really looks like an Oldsmobile Qjet.

[joe_padavano]

This is what a 7027240 Qjet looks like. Note the differences in the inlet, the choke, the throttle arm, the bowl vent, and the shape of the castings. That one on Craigslist isn't even close.

 

[Deadpurpledog]

Really helpful. . .thanks Joe.