C4AFDG Autolite 4100 question

tdyltc66 · #1 (**permalink**) 10-11-2015, 06:06 PM

Hi guys, I am completely new to this forum and this is my first of what I hope will be many posts. However I must confess that I am not a Shelby Cobra owner, although I would very much like to be. I own two classic Mustangs: A 1966 200 c.i. 6 cyl. 3-speed convertible and a 1965 289 c.i. 271 h.p. hi po 4-speed coupe. I hope that this does not disqualify me as a member of Club Cobra. The subject of my post concerns the 289 hi po car. I am in the process of rebuilding the C4AFDG Autolite 4100 carburetor. I have two questions:

There are two small, what appears to be, brass pieces; flat, 1" X 1/2", with holes in the middle. The vertical manual choke rod that activates the choke plate passes through the holes in these brass pieces. As far as I can tell, these pieces of flat brass serve no useful purpose; other than to bind up the choke rod. does anyone have any idea what these things are and what, if anything, they do?

Also does anybody have an opinion regarding the need, or lack thereof, of a check ball in the vacuum secondary circuit? From what I have read these elusive check balls are absent more often than they are present. My 4100 did not have one.

Any thoughts would be greatly appreciated. Thank you. tdyltc66

LMH · #2 (**permalink**) 10-11-2015, 10:33 PM

I think the 4100 AF-DG isn't the correct carb for a 289 HiPo, though it probably doesn't matter a lot unless it's a concours car. But I believe that carb was originally an auto choke unit and may have been changed to manual choke. Makes me wonder if it doesn't have some home made linkage that's screwing it up. With the exception of the rod going to the choke flapper, my 4100 has no brass parts of the choke linkage. Everything pretty much is gold cad plated steel. That also makes me think home made. Could that be what's going on?

As far as the check ball for the secondary diaphragm, I'm not sure. I've seen 4100's with and without. I think they may have dropped using it depending on the size of the secondary vacuum port but I don't know enough to say for sure. These are the people you want to talk to about it: Carburetor, Carburetors, Carbs, Carb Parts. Pony Carburetors - Your Ford Carburetor Restoration and Part Sales Specialist

Larry

Dan Case · #3 (**permalink**) 10-12-2015, 04:43 AM

I'll go with Larry that your carburetor has been modified. Ford 2100/4100 carburetors had vertical choke link seals in their designs. There is a felt shaft seal or gasket that provides some sealing (keeps big debris out) the large oval passage in the carburetor body. Low pressure inside the air cleaner/ carburetor upper end would pull the seal through the large oval hole so there is a thin brass retainer to cover much of the large oval passage. All the parts are free to easily move laterally.

Carburetors with damaged or missing link seals are very common. Here's some images from a new old stock HP289 specific 4100 model.

LMH · #4 (**permalink**) 10-12-2015, 06:58 AM

Mine doesn't even have that seal or retainer. Shows you how much they get 'modified' over time!
Larry

domenic saia · #5 (**permalink**) 10-12-2015, 07:35 AM

I think the seal is to only get filtered air.....

LMH · #6 (**permalink**) 10-12-2015, 07:52 AM

Checked, mine does have the retainer. Seal is gone though.
Larry

tdyltc66 · #7 (**permalink**) 10-12-2015, 09:46 AM

Thanks for the replies Larry and Dan. I new I could count on the Cobra guys for the answer. That's it exactly; that explains the mystery of the two little "brass" pieces. I am not sure why there are two little "brass" seals though; it seems like one would do. Maybe one goes on each side of the felt washer. Speaking of the washer, I wondered what that little white washer in the rebuild kit was for. The clip to retain the two seals is in tact on my carburetor so I guess I got lucky there. Larry, you are correct; my carb was not original to the Mustang 289. It was originally used on the 1964 Ford Galaxy 352. Which would have had an automatic choke. Fortunately, I don't believe any modifications were made to the carb. (other than the manual choke). Everything is in tact and appears original, according to pictures I have seen. As far as the check ball goes, I put it back together the way I found it: without the check ball.

Dan Case · #8 (**permalink**) 10-12-2015, 10:25 AM

PM sent.

tdyltc66 · #9 (**permalink**) 10-12-2015, 03:57 PM

Thanks for the PM Dan, that is exactly the kind of information I was looking for. I do have access to air so I will conduct that bench test that you described. My car is only occasionally driven: to cruise nights and local car shows and such. It is never raced or horsed around, unless you count the occasional quick departure from a stop light (and who can help themselves in a situation like that). So unless someone is willing to trade me even up for a 289 hi po specific 4100 carburetor, I guess I can live with the slightly under performing C4AFDG. Don't get me wrong, I would love for the car to be correct in every way, so if you know of someone willing to trade, I would like to talk to them. Maybe I could go on A big Ford or Mercury forum and find some one who has the opposite problem. Thanks again for your interest and help. tdyltc66

tdyltc66 · #10 (**permalink**) 10-12-2015, 05:23 PM

Apparently knowing what those little brass things are, what they do and where they go is only half of the battle. I cannot figure out how the heck the two brass pieces and the little felt washer get to where they are supposed to be. I know it's got to be some kind of Rubik's Cube trick, but I was never any good at those either. Does anybody have any idea how these pieces install?

All is well. I was trying to install them without bending the little retainer. It can't be done. Once I bent the retainer down, the pieces slid into place easily. Then it was just a matter of bending it back up with a small pair of needle nose plyers.