Question on 1968 Quadra-Jet Rochestor Carburators

[Larry E.]

Starting to collect some parts to make a "display" engine. Engine will be a 1968 L36. Have the proper I/M
#3937793. Date codes will not be important for this engine but physical appearance will. I have Rochestor
Carb#7028207 (300 HP S/T) carb. Correct Carb is #7028209 (390 HP S/T). Would there be any physical
appearance differences between these two carbs? For that matter what is the exact differences between
these two carbs internally? Thanks in Advance--Larry

[William C.]

Re: Question on 1968 Quadra-Jet Rochestor Carburators

I can't answer all your questions, but different needle and seat and different pump assy different "power kit" (don't know what is contained in this) are some of the differences.

[Joe L.]

Re: Question on 1968 Quadra-Jet Rochestor Carburators

Starting to collect some parts to make a "display" engine. Engine will be a 1968 L36. Have the proper I/M
#3937793. Date codes will not be important for this engine but physical appearance will. I have Rochestor
Carb#7028207 (300 HP S/T) carb. Correct Carb is #7028209 (390 HP S/T). Would there be any physical
appearance differences between these two carbs? For that matter what is the exact differences between
these two carbs internally? Thanks in Advance--Larry

Larry------


Except for "numbers", the '207' and '209' carbs were essentially the same externally. However, as far as the components of the two carbs, most were different in some way. This includes the air horn assembly, the float bowl assembly, the throttle body assembly, the primary jets, the primary metering rods, the secondary metering rods, and the float. I don't think, though, that there were any significant externally discernable differences between the air horn, float bowl, and throttle body.

[John B.]

Re: Question on 1968 Quadra-Jet Rochestor Carburators

Larry, Certainly not a 7028209 expert, but my research in trying to find one for my 1968 L36 has led me to believe that the choke pull-off linkage for the Big Block was much different than that for the small block. I do not have a picture of the big block linkage, but maybe someone else has one they can send you. I was able to buy a 209 many years ago, before I knew much about them, and it has the small block linkage installed. I've been searching for another core or the correct linkage pieces, but seems like trying to find a needle in a haystack. I was told by several quadrajet rebuilders that the choke linkage on the 68 L36 was unique to the 68 corvette.

Regards,

John

[Larry E.]

Re: Question on 1968 Quadra-Jet Rochestor Carburators

Larry, Certainly not a 7028209 expert, but my research in trying to find one for my 1968 L36 has led me to believe that the choke pull-off linkage for the Big Block was much different than that for the small block. I do not have a picture of the big block linkage, but maybe someone else has one they can send you. I was able to buy a 209 many years ago, before I knew much about them, and it has the small block linkage installed. I've been searching for another core or the correct linkage pieces, but seems like trying to find a needle in a haystack. I was told by several quadrajet rebuilders that the choke linkage on the 68 L36 was unique to the 68 corvette.

Regards,

John

John: Thanks much for added info. Now FWIW I also have a 7028212 (Automatic Trans. Carb for S/B Camaro's/Chevelles I believe. It bolted up
fine with the I/M #3937793 and the choke coil in the manifold. Unless someone "reworked" this carb it looked/hooked up fine. I did not try the 7028207
and can not now as the I/M is sent out to get "reskinned". Hopefully it will be OK with the 7028207. Larry

[Joe L.]

Re: Question on 1968 Quadra-Jet Rochestor Carburators

Larry, Certainly not a 7028209 expert, but my research in trying to find one for my 1968 L36 has led me to believe that the choke pull-off linkage for the Big Block was much different than that for the small block. I do not have a picture of the big block linkage, but maybe someone else has one they can send you. I was able to buy a 209 many years ago, before I knew much about them, and it has the small block linkage installed. I've been searching for another core or the correct linkage pieces, but seems like trying to find a needle in a haystack. I was told by several quadrajet rebuilders that the choke linkage on the 68 L36 was unique to the 68 corvette.

Regards,

John

John-----


The 7028209 did use a different choke vacuum control bracket assembly than the 7028207. Just how it was different, I do not know. That bracket assembly was GM #7036368. It was discontinued in February, 1974 and replaced by GM #7042363. The latter was discontinued without supercession in 1977.