1967 Q-jet Carb Question

[60s GM Fan]

[rocketraider]

That's it.👍🤙

 

A quick search turns up 7241 as a 1967 Buick 400/430 application, probably for an AIR equipped engine (smog pump). May be calibrated a little leaner than a non-AIR application.

 

Once it's torn down for cleaning, evaluation and rebuild, you'll be able to determine jet sizing and metering rod diameters. Then you can determine if this carb is suitable for your Wildcat. Right now I think yes, especially if it has the updated needle and seat.

 

But sounds like anything would be an improvement over what you have.🤪

[carbking]

1967 Buick 430 California.

 

If you are taking it apart, the primary jets should be changed to 0.071, and the primary rods changed to those stamped 37.

 

A bit of trivia:

 

The square hole in the tag denotes California; Federal carbs had a round hole.

 

Carter carbs, with the normal triangular tag, had square tags on California carbs.

 

Jon

[60s GM Fan]

Thanks Jon.  I'm glad I have the right core to work with.  I was told to plug the inlet from the base plate since that was part of the SMOG setup.  Are there any other tuning tricks, etc for this particular carb and my 430?

[carbking]

I am not an expert on converting California to Federal; which is why I look at the books.

 

The Rochester Master Parts manual states that, at least on the 7027241, the throttle body assembly is the same as on the federal 430 carb.

 

Jon.

[60s GM Fan]

Jon this is good news.  My car is running okay right now with the frankencarb that my mechanic toyed around with.  I'm really looking forward to giving her that extra umph that she needs.

[rocketraider]

3 hours ago, 60s Buick Fan said:

Thanks Jon.  I'm glad I have the right core to work with.  I was told to plug the inlet from the base plate since that was part of the SMOG setup.  Are there any other tuning tricks, etc for this particular carb and my 430?

On some carlines, that big fitting is either for PCV valve or power brake booster. Make sure before you cap it. I'm not as familiar with Buick as I am Olds and Pontiac but if you have the 67 Buick factory Chassis Service Manual it should show all carb vacuum connections.

 

Offhand I can't remember any smog pump vacuum connections unless maybe to operate a diverter valve. You don't have the Air Injection Reactor so it's a moot point.

 

Oh, there are all grades of QJet performance tricks if you can find the parts to do them! That's why people choose oversized Holleys over the much finer QuadraJet- Holley's aftermarket support is easier to find and tune. Holley makes a nice tunable carb, but out the box they're a one-size-fits-none compromise.

 

I will say this has been one of the most interesting and informative threads I've read in some time. Hopefully my input has helped and not hindered!

[EmTee]

20 hours ago, 60s Buick Fan said:

I was told to plug the inlet from the base plate since that was part of the SMOG setup.

Can't you swap the baseplate from your original carb?

[carbking]

1 hour ago, EmTee said:

Can't you swap the baseplate from your original carb?

NO!

 

NOT interchangeable!

 

Jon.

[rocketraider]

You'd be right back where you started since each GM Division had its own idle bleeds, internal vacuum passages etc on their QuadraJets. If the throttle plate and float bowl are mismatched things might work, but not optimally. Especially between a Buick float bowl and a Chevrolet throttle plate.

 

4GC are known to have issues if even the wrong gasket is used between float bowl and throttle plate. QJet isn't quite as bad about that but why tempt fate?

 

If the big vacuum fitting isn't used for PCV, power brakes, or other vacuum-operated accessory put a rubber cap on it. If it's threaded into the throttle plate remove it and install a suitable pipe plug.