Autolite 4100 questions

[S7MS427]

I have a couple of questions regarding Hi-Po Autolite 4100 carburetors.

1. Other than the dashpot, what is the difference between the manual transmission version of this carburetor (C6ZF-C) and the automatic version (C6ZF-F)?  Is there a difference in calibration?  I know the secondary boosters are the same (stamped BA) but are the primary boosters (stamped M or MA) different?

2. The attached picture shows two styles of Autolite 4100 manual choke brackets.  The question is which one would be correct for an early February build Hertz car (shipped 2/10/1966)?



Thanks for any help provided.

[Dan Case]

From Bob Mannel's database:

C4OZ-9A523-B primary support (a.k.a booster venturi cluster) stamped M = used in carburetor C6ZF-9510-C (52F/68F jets and BA secondary support) for manual transmission applications

C4OZ-9A523-C primary support stamped MA = used in carburetor C6ZF-9510-F (50F/69F jets and BA secondary support) for automatic transmission applications

This new old stock C6ZF-C carburetor made during the fourth week of February 1966 was for sale recently.

[S7MS427]

Dan,

Thanks for the response.  I'm pretty sure that the more square style bracket is earlier than the other.  I figure that my car might have been built somewhere around the change over date.  We'll have to get a few more folks chiming in in order to get a read between the two styles.

[CharlesTurner]

The squared/straight one was definitely used on earlier hi-po carbs.

[Dan Case]

Manual choke model carburetors for HP289s 1964-65 with numbers starting with C4OF and C5OF used this design and arrangement. The C4OF-AL model for manual transmissions was introduced in Fairlanes mid April 1964 and is as far as I know the first 4100 to use a manual choke. The C4OF-AT was introduced in Fairlanes around May 1964 for a very short run of HP289 engines assembled for use with High Performance C4 automatic transmissions and was reused again for the 1965 model year Fairlane with High Performance 289 and High Performance C4 transmission. As the 1965 model year run started carburetor bodies already stamped C4OF AL were built into C5OF prefix assemblies. All these at least through fall 1964, deep into the 1965 model year, used the design below.



I high recommend the digital version Bob Mannel's book for anyone that does their own carburetor work or those wanting enough information to check out units before they buy them. Most assemblies that have been through a commerical rebuilder are likey to now have non-stock parts. It is frustrating to find a HP289 carburetor, buy it, and find all the calibrated parts have been swapped out for something else.

[S7MS427]

I did pick up the digital version of Bob Mannel's book "Mustang & Ford Small Block V8, 1962-1969".  Looks like a good resource, especially since I am trying to rebuild my original engine for 6S817.  It won't be concours correct but I want it to be somewhat close without spending ridiculous amounts of money.  At this point I have all the really hard to get parts.