RapidRuss, I was speaking of the 428SCJ not the 429 and both the 428CJ and the 428SCJ came with a 735CFM Holley. Actually it started life as a 780 but the booster venturis belled out in the primaries to make the holes smaller and cause higher air flow and quicker transition to the main jets. Also both the 428 engines ran a hydraulic cam but the SCJ had a stronger crank and rods. I know this info from owning and racing both a CJ and SCJ in 1969 Cobras; the Fairlane body style, the CJ in a Fastback with all the goodies including ram air and the SCJ in 3400lbs Notchback striped version that was very quick, plus I looked in my old Ford Muscle Parts books to make sure that the 57 year old mind wasn't remembering strange stuff again.

 

What it all boils down to is getting sufficient booster signal in the carb venturis. Without it you have a lazy slug, especially with high-overlap cams. If you achieve sufficient booster signal you can run virtually unlimited CFM with no problem- look at the engines fitted with Webers- well over a 1000 CFM, or more. However, they get the adequate booster signal by, as someone observed, using eight small holes rather than fewer, bigger ones. Larger carbs, like the 850, have (typically) poor boosters as installed by Holley, & poor booster signal, due to the big venturi size. Annular boosters help immensely, but, you have to go to a specialty vendor to get a std. 850 fitted with them, or buy one of the special models with them from Holley at the start. Most of the specialty guys choose to use a 750 Holley in the first place, to get better signal, & then use 850 baseplates, mill the choke horn, thin the throttle shafts, etc. to pick up CFM. This is very effective until you get into some pretty serious horsepower or engine size. That's when you start looking at the Dominators or the 950 Holleys. The Dominators are a whole different design & have various features, notably four-corner idle, & so forth, which helps them work with nearly anything, within reason. All that being said, for the vast majority of people who don't have the skills, time, money, ambition, or love of self-inflicted pain, I'm with Bear- use the smaller Holleys, they'll be much easier to set up & 90% of people can't tell the difference. My only objection to them is that, because they essentially use the same main bodies as other Holleys (of their specific type, that is), the castings have very thick walls around the venturis and tend to retain heat, which can cause some erratic mixture distribution problems at times. I always use a wood or phenolic spacer, or a heat reflection plate, under them- a good idea with any carburetor, really. This concludes my lecture for the day! Mike