1970 carb main bodies

[Edward M.]

Does anyone know if the main body for all 1970 Q-Jet carbs is the same? Is the main body for a 1970 350 ci, 300hp auto application the same as the main body for a 1970 454 ci, 390hp manual application.

In other words, can you use a base motor carb, with different parts (jets, metering rods, etc) on a big block car? Is the appearance, other than the numbers, close enough to pass judging scrutiny?

[Jim T.]

Re: 1970 carb main bodies

Ed looking at a quick reference, the Corvette Black Book, lists 13 different numbered Rochester Q-jets for model year 1970. The main body is where the numbers are, so I would reasonably say that the judges could tell by the numbers. Last time I talked to you a few years ago in Milan I remember you working on a 56 Corvette, how is it coming along?

[Joe L.]

Re: 1970 carb main bodies

Ed-----

There are different part numbers for the air horn, float bowl, and throttle body assemblies for 1970 carburetors depending upon whether the application is 350, 454, auto, manual, hi-perf/non-hi-perf, and EEC/non-EEC. However, as far as external CONFIGURATION is concerned, I don't think that there are any differences in these parts for any 1970 carb. I believe that you could configure the internal components to match the application. However, and as you point out, there would obviously be a difference in "numbers" and that fact would not escape "judges" scrutiny. Since "numbers" seem to have more importance than configuration, I would expect that the "hit" that you would sustain for that deficiency would render moot any further "benefit" of original configuration. That's just an OPINION, though.

[Edward M.]

Re: 1970 carb main bodies

What I am concerned about the the physical appearance of the carb main body itself. Please forget about the numbers, and any other part that bolts onto the main body. FYI: What I am calling the main body is that one cast part that actually has the numbers stamped into it. It probably has a correct name oher than main body.

Ok, back to my question. Are all 1970 Q-Jet main bodies physically the same. Can you look at just the main body for a 300hp 350 car vs. a 390hp 454 car and point to a physical difference. Remember, ignore the numbers stamped on it. Is there any thing else that would differentiate the main bodies?

The 1956 project is long gone. I lost interest and sold it as a project about a year ago. It went to a good home in the Atlanta area.

[Joe L.]

Re: 1970 carb main bodies

Ed-----

The "main body" of the carburetor(the part with the "numbers" stamped on it)is called the "float bowl assembly". There are 3 main parts of a Rochester Q-Jet carburetor: the "air horn assembly", which is the "top part"; the "float bowl assembly" which is the "middle part"; and the "throttle body assembly" which is the "bottom part". As far as I know, the EXTERNAL CONFIGURATION of the "float bowl assembly" for ALL 1970 Corvette Q-Jet carburetors is the same.

[motorman]

Re: 1970 carb main bodies

the biggest diference in carb body is the size of the drilling in the air bleeds and the idle feed circut. the reason there are so many different carbs for the same engines is because of the cam,compression, and under hood air flow, etc.

[Edward M.]

Re: 1970 carb main bodies

Does the float bowl assembly carry a part number of its own? Or is this case of all you could order was a whole carb ("no user servicable parts inside")?

[Joe L.]

Re: 1970 carb main bodies

Ed------

Basically, all of the parts of the carburetor were once-upon-a-time available seperately, although they are no longer available for most of the Q-Jet component parts. Usually, the first things to get discontinued were the major components, then smaller components, and lastly, the complete carburetor assemblies. There are, however, a few parts still available from GM for the early carbs, but mostly only minor rebuild kits, floats, and a few small parts. The GM part numbers for the 1970 float bowls were as follows:

7036811-----all 454

7036839-----all 300 hp 350 cid

7036840-----all 350 hp 350 cid

As I mentioned previously, I believe that all of these had identical EXTERNAL CONFIGURATION.