quote:
Originally posted by "72 GTS:
... I already have one Holley Strip Dominator intake (high single plane) ... I guess that the port reduction is a professionnal job, I won't be able to do that ...
Philippe,
Do not stuff the intake ports (port reduction) of the iron 4V heads in conjunction with the Holley Strip Dominator intake manifold, that manifold is designed for a full size port.
The port works good as is, and the best names in Motorsports had a hard time figuring out how to make it better. The guys who filled the port back in the heyday of iron head 4V pro-racing were doing so not to increase velocity, but to eliminate the irregular shape of the port, because at the engine speeds they were racing at (above 8000 rpm) the irregular shape caused the fuel to fall out of suspension, it was wetting out on the walls of the port.
Stuffing the intake port will decrease air flow by at least 15 cfm at 0.600" valve lift, and by at least 25 cfm at 0.700" valve lift. So if you stuff the port, the port needs to be reworked to regain the air flow. The velocity increase attained by stuffing the port inlet is minimal, port volume is only decreased by about 15cc ... and even less once the port is reworked. My advice is to get to know the port, understand how it works and do the math to know the various operating parameters (average velocity, peak velocity), before making a decision to modify it. The more you know about the port, the better you'll understand how well it was designed to begin with, that I guarantee.
quote:
Originally posted by PanteraDoug:
... I have no experience with that recommended carburetor ...
Doug the Quick Fuel carbs (aka QFT) are Holley clones, with features like fuel bowl windows, replaceable air bleeds, etc, that Holley owners can only wish they had ... or that they pay a bunch of money to have installed. The double pumper versions are available with annular booster venturis. They are generally considered to be a better out-of-the-box carburetor than those manufactured by Holley.