Hi Guys, Great stuff. Kelly, I have an early in-line small carb (875 cfm). With "XF" number cast into it. The carb looks like it was sand cast, and has DOFF instead of DOZX on the tag. The serial number is 14 if I can recall correctly.
Yes Gus, I have seen some of these early units but less than a handful and only on the smaller version carbs. You have a very early experimental engineering unit. It's likely that these early units were only released to people very close to Ford at the time (not likely sold) and most if not all carried experimental part numbers and were built from temporary tooling. There distinguishing features are noted in the pictures I have inserted below. The most obvious difference is the solid area underneath the throttle arm that couples the throttle plate shafts. The production version is more refined because it is an open architecture in this area whereas the closed sand cast version could gather debris and cause the linkage to bind and stick. You are correct about them being sand cast. If you compare them side by side you will not there are no ejector pin marks as there are on the production permanent mold/die cast tooling. Usually the sand castings only apply to the throttle plate (bottom casting) and the venturi plate (top casting) and the the main bodies (containing the main well) were already hard tooled by that time and have the Ford logo cast in....but not always!
It came from AK Miller back in the early '70's. I bought my Boss car and intake set up from the same owner who got it from Ak Miller.
Like I said, the early ones were given to the fair-haired children/Ford desciples
[/quote]The unique part is that this in-line carb has been modified to a 750 cfm, which I would think is better for a cross boss intake on the street. They made smaller venturies and butterflys, I also got the originals as well. What do you think? [/quote]
And butterflies? I would noy have though the latter to be necessary. Out of curiosity, did the press in inserts to the bores or were they machined to a smaller diameter from the raw casting? In general though, per my previous comment, yes, 750 cfm is better for a street going Cross Boss and in general that large open plenum does not need the bigger carb flow to handle peak surge as the large plenum can do that. The smaller carb enables a stronger booster signal and more response in the the streetabkle range.
I often wonder if anyone else ever changed there cfm? you could tailor the carb to the engine. Yes it's a lot of work, but nothing a lathe and mill couldn't handle. Just my 2 cents. Gus
Yes, I've seen it done many times. Most frequently by those who have a 1425 cfm "B' carb and want it to behave like an 875 "A" carb. It doesn't work very well because small rotation of the comparatively large 2.25" throttle plate looks like WOT to a small venturi. I have seen some slightly smaller venturis used with success on the larger "B" carbs in IR on 302-351 CI engines.
Gus, if you ever want that carb gone through, I'll take good care of ya. These historical pieces deserve some respect and can contain some educational surprises for guys like me.