This has been an ongoing battle with me and this 489FE street Mustang
Part throttle steady buck and a slow to respond transition circuit in the 1500-2000 rpm range, dont think "idle" dont think "WOT" think about driving around in town.
I have it at sort of at bay by decreasing IAB size and increasing IFR area, but its just a bandaid adding a ton a fuel in those circuits, and having it come in early, its rich, and its not right, but it covers it a little and makes it acceptabl. I dont like it though and want to be able to work the entire curve, hence the new blocks
I am not alone, lots of guys with the HP series and Street Avenger carbs are fighting it. All other normal tuning and troubleshooting comes up short, standard "add timing", smaller IABs, more IFR, etc, can move it slightly or bandaid it, but guys that play long and hard with WB O2 data seem to have come to the conclusion that its a HP, Avenger, and Barry Grant emulsion problem (I am not a wideband O2 guy, but may buy one seeing the data they have to work with with the new recorders)
The mixture issue is high vacuum, light throttle, low rpm. As you'd expect, I didnt have the issue with a moldy old 4781 I had on the last iteration of the motor, but have fought it continuously since I put the modern carb on.
With that being said, by the time I drill every passage and put removable bleeds in them, why not just buy a billet block with the labor done already?
My question is if anyone has had success or failure with either of those companies, as they both seem to be selling billet plates pretty easily these days and does anyone know the difference in the emulsion characteristics of each?
Ironically when I called QFT to ask what caused the "more agressive" fuel curve in their carbs, they said "its designed that way", I asked, what changed it, they handed me off to the expert who said "its more agressive" LOL
I have not called BLP, but will Monday.