The 4760 is the carburetor to use if one requires a single 750 CFM 4-barrel AFB. The 4762 is a "companion" unit with no choke for those wishing to put (2) 750 CFM 4-barrels as an in-line dual quad with progressive linkage (rear carb primary, front carb secondary). The 4762 has no choke. Other units in the "competition series" AFB line are: 4758 500 CFM with manual choke 4759 625 CFM with manual choke 4761 500 CFM with no choke For some reason, there was not a 625 no choke version. Jon.
How'd you guess? :grin: :bglasses: I see there is also a #9755 offered in a 750cfm Competition Series....it looks to be a newer model, having a polished (or plated?) aluminum body. The carb top also looks a bit different. Is there a website with alot of AFB info? I haven't been able to locate any. I'm also looking for parts...secondary air valve, linkage rods, new screws, etc... Thanks for your help, Jon!
There is a newer "competition series" (post-1985) that, while some of the units say Carter, they were actually produced for Federal Mogul by Weber. The Federal Mogul/Weber/Edelbrock AFB-clones should not be confused with the genuine Carter AFB carburetors, and one should not try to run mismatched units together. The 9755 belongs to the newer series. I cannot help you with these. I am unaware of a good Carter website that offers specifications. I understand Edelbrock has one for the clones, but that would not be applicable to the genuine Carters. Parts such as you posted are available from some specialty companies, at least for the genuine Carters. Be aware that these carburetors are calibrated for Chevrolet engines (low torque, high RPM). If you are placing them on a Buick, you will need to change the metering rods, and secondary air valves (possibly the idle tubes) for a really good setup. The metering rods have too great a difference from the high vacuum to the low vacuum step and will result in incorrect mixture at either the high vacuum or low vacuum (or both) conditions. The attack angle of the secondary air valve is too aggressive for a high torque engine, and will normally result in a momentary hesitation in the transission from primary to WOT. The idle tubes may not permit sufficient idle mixture for a good idle on the high torque engine. Jon.
Thanks again for the advice Jon! This setup will be primarily for race use, so items like idle quality won't be a prime consideration :bglasses: I'll pay particular attention to the other items you mentioned. I did find a great 38-page guide on AFB tuning direct from Federal-Mogul: Carter AFB Tuning Manual: http://www.federal-mogul.com/fmeconnect/technicalservices/downloads/1602.pdf Carter AFB Selection and Tuning Guidlines: http://www.federal-mogul.com/fmeconnect/technicalservices/downloads/1601.pdf I HIGHLY recommend them!
Thanks for posting the links. We have the information in one FM form or another, but nice that it is available on the web. Please note that this information is applicable to the Federal Mogul AFB's (and probably also the Weber and Edelbrock clones). All of the numbers in the chart are FM only (as opposed to Carter); EXCEPT the 9635, 9636, and 9637. These can be identified as Carter or Federal Mogul by looking at the suffix following the number. For these three numbers, the Carter will be an "S" while the Federal Mogul will be an "SA". Information for the real Carters can be found as follows: (A) Carter Competition Catalog (print date prior to 1985) has an excellent section on the early competition carbs, as well as the 9000 series. Also, has a O.E. calibration chart for many O.E. carbs. (B) Carter AFB Circuit manual (cutaways and descriptions of the various circuits). Much of this information is contained in the first posted link. (C) Factory shop manuals for the various makes (ie Buick). Carter made more than 500 different AFB carbs. While the aftermarket units had somewhat of a universal fuel curve (slanted toward high rpm Chevy engines); the O.E. carbs did not, and were specifically calibrated for a given application. Since you will be using your dual quads in a race environment, you are correct that many of the issues normally problems in a street environment will not be present (ie idle, off-idle, high vacuum cruise). I do believe you will experience a "sag" or "bog" unless you can keep the RPM at a level that the secondaries never are closed. If you do experience that bog, locate a couple of junk O.E. Buick AFB's and switch out the secondary airvalves. This switch normally good for 0.3~0.5 second in the quarter mile. Jon.
Wow! that could put me in the 12's !:grin: Does this delay the opening of the secondaries? I understand I can accomplish this by adding weight to the secondary air valve...drill a hole and add lead to the hole. I do need a replacement secondary air valve for a Carter 750 comp series... Where can I get one/ Thanks again Jon!
