Thread: Rochester compatibiliy

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This may be a stupid question but, are Edelbrock Qjet and Rochester parts interchangeable?

Actually this is a very good question with a somewhat complex set of answers.

From the “air cleaner” up they’re 100% compatible! Seriously – that’s the only 100% correct answer. There are a couple considerations.

First part of the “the answer” - Edelbrock used to sell (from time-to-time) Q-Jets that were reconditioned (not new) Rochester carburetors. They built them back to factory original specification and these were really good units in terms of quality and reliability however; they are somewhat rare as the source (original Q-jets) has long since dried up. In the past, they were available direct from Edelbrock, but I do not see them on their web site anymore so they may be out of the “rebuild” business. Tricky part here is the linkages as Edelbrock rebuilt “Chevy-only” Q-jets and if you wanted to use them on a Buick, Olds, Pontiac or Caddie, you needed to swap in the original brackets and kick-down linkages. This situation was exacerbated by the “cash-for-clunkers” program when the government paid people to trash a lot of 1970-1980 cars that were originally equipped with Q-jets. The program required these cars to be disabled and more often than not, they were crushed with the engine intact so the carburetors were destroyed.

Second part of “the answer” - Edelbrock used to market a “Performer Replacement Series Carburetor for Q-Jet” which was an “all new” carburetor intended to replace the original equipment Q-Jet spread-bore carburetors on 1966 -1989 non-computer controlled Chevrolet/GMC V8s. These carburetors look very similar to Q-jets (even gold color) however there are some very subtle differences and the internals are not interchangeable with Rochester manufactured Q-Jets. The Edelbrock replacements are (for the most part) compatible with all OEM linkage and bolt on to the stock intake manifolds. I have used the 1901 and 1902 over the years but they are not easily found anymore. One way to know you have an Edelbrock Q-jet is that they use Torx head screws. There were five distinct models of the Q-Jet replacement (this from an old Edelbrock tech-sheet dated 2002 I’ve for whatever reason kept in my files!!):

1. #1901 (750 CFM) - Recommended for most small-block and big block Chevrolet/GMC V8s, 327 through 454, in both truck and passenger car applications using a remote style choke; 1966 to 1973.

2. #1902 (750 CFM) - Recommended for most small-block and big block Chevrolet/GMC V8s, 350 through 454 in both truck and passenger car applications using a remote style choke; 1974 to 1978.

3. #1903 (795 CFM) - Recommended for most small-block Chevrolet/GMC V8s, 305 through 454., in both truck and passenger car applications using a hot air style choke; 1975 to 1985. (Electric choke conversion – needs a switched 12 volt lead.)

4. #1904 (795 CFM) - Recommended for most small-block Chevrolet/GMC V8s, 305 through 350, in truck applications only using a full electric choke; 1980 to 1989.

5. #1906 (795 CFM) - Recommended for big-block Chevrolet/GMC V8s-454 engines in truck applications only using a full electric choke; 1980 to 1989.

Summit, Jeggs, and others may still sell rebuild kits for the Edelbrock units, but only until their stocks are depleted. I occasionally see one at a swap meet but I’ll not pay more than $25 bucks for an “unknown” carburetor – regardless of the seller’s claims of “recent rebuild” unless it’s an original unit that I know and might be looking out for.

Quick answer – not a lot of interchangeability between “true” Rochester Q-Jets and the Edelbrock units..

The good news is that Summit and others still have rebuilds of the originals for reasonable prices and that's a good way to go if you want a Q-Jet which, in my opinion, was the best factory carb ever used by GM..

Regards,
Glenn

Thanks for getting back to my question so quickly. The car has the original Rochester. I have a chance to buy a couple of Edelbrocks cheap. I was going to swap out jets and metering rods. But now I know that will not work. Summit and a couple of other sites carry rods and jets. Again, thanks for the quick reply.

My pleasure - hope you hang around here a bit and share with us what you're building..

As to buying the Edelbrocks cheep - which model and how much? There's always folks here looking for parts and the 190x Edelbrocks are getting hard to come by.. Let us know and you may find some interest here.

Regards and Welcome to CHR,
Glenn

Good answer Glenn. I considered a Q-jet a while back, asked a bunch of questions of some knowledgeable folks, got some answers that I really didn't want to hear and decided that an adapter/spacer really didn't make much sense on a Ford 4 hole Performer RPM intake. Sooooo now I have a $20 swap meet spare Performer 600cfm, 1405 that has just taken a Berryman Carb cleaner bath and will be reassembled to as new and just waiting its turn

There you go Dave! Swap meets are a great place to find some real treasures. I too like the 140x series as well and have used a bunch of them. Fire up right out of the box and are real easy to tune to a wide variety of engines..

For a good book on rebuilding and tuning QJs get Cliff Ruggles book. Amazon has it for $17.56 or Google Cliff Ruggles to get it direct. If you call him direct he is a pleasure to deal with and willing to share his knowledge.

Jack