And at what RPM are you launching those 1407 s ???
Street Versus Race And Off Idle / Flat Spots Versus RPM are completely eliminated
Edelbrock 1407/1411 where notorious for off idle flat spots / going lean on Big Block Mopars on the street
No damn drill bits where fixing those - Maybe a garbage can or EBay
I like the factory Carter AVS found on the 69 - 71 440 HP motors - So easy to tune when converted over to Eddy internals and flat metering rod covers
With that said , I Absolutely LOVE my Eddy AVS 2 800 - Idle and Off Idle are flawless / perfection to say the least on a street car
Anyways 1407/1411 - From Speedtalk
The secondary venturi cluster emulsion tube is “pinched” at the bottom with a .073” orifice the fuel must pass through to enter the tube to get up to the discharge nozzle….. and (it gets worse) …… the secondary Main Air Bleed is .073”. Imagine what a Holley would do if it had a .073” bleed in the booster leg.
The reason it doesn’t seem to matter what jet size is used is the .073” air bleed kills the venturi signal and no matter what main jet size larger than .073” is used the fuel must pass through the .073” restriction downstream of the main jet.
As if that isn’t bad enough, the primary MAB (the tube pressed in the top of the cluster) is occasionally very large, .040” or more, and occasionally different on left and right.
Occasionally the idle jet (the small tube pressed in the bottom of the cluster) is different left and right and sometimes the idle jet larger than necessary, resulting in a very rich off-idle.
The 1407 750 CFM uses the same casting for the primary cluster as the 625 CFM carbs in spite of the fact the venturi minor diameter is 5/16” or so lower in the 750 body. This places the exit of the booster venturi that much above the “vena contracta” in the air flow, the result is the “booster signal” is not obtained in the correct location and the metering is erratic, the A/F wanders rich and lean as load and RPM vary as the throttle position is changed.
as for your speed talk quote, and i've read this before, if a careful look is taken at the cluster in question you'll notice an additional flow tube that does help that matter, but if there still is an issue with size the "special" drill bits from a set of number drills solves the problem. there are also clusters out there that have a straight thru emulsion tubes that aren't swaged down. a concern to me with edelbrocks (not the old sand cast carters) is the fuel passages from the jets to the cluster wells. the edelbrocks are smaller and not machined near as nice as the old stuff. holley's do have better and larger fuel passages that could be a make or break deal for someone in competition.
